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Tucson Amateur Packet Radio Corporation

April 1992 President’s Corner Issue # 46 by Bob Nielsen, W6SWE

The annual meeting on March 7th and 8th was an unqualified success. The Published by: attendance was well over 100 and all of the reports I have received have been very Tucson Amateur Packet Radio positive. The sales of the new 9600 bps modem have exceeded our expectations, PO Box 12925 and, as I write this we are currently out of stock on these, with several backorders. Tucson, AZ 85732-2925 Circuit boards and parts are on order and hopefully all orders will be filled soon Phone: 602-749-9479 FAX: 602-749-5636 after you read this. We plan to have adequate quantities at Dayton, as well. There Office Hours: have been a few necessary part changes which came out of some of the results of Tuesday - Friday early builders/testers, and these, as well as additional information have been sent to 10:00am - 3:00pm M.S.T. all who bought the kits. Thank you to those who have provided feedback. This 17:00-22:00 UTC project was rushed along without our usual beta test phase to clean things up. The TrakBox sold well also, as did many of the kits and other things which were available Editor: previously. We also signed up several new members. The order form included with Bob Hansen, N2GDE this copy of PSR contains these new kits plus a few price changes for existing items. POBox 1902 On Friday, March 6, the TAPR Board of Directors met and voted to reduce the Elmira, NY 14902-1902 PSR. CompuServe: 71121,1007 size of the board, as I discussed in the last issue of We have gone from 15 to 9 members (Don Lcmley, N4PCR, resigned from the board shortly before the meeting). We chose officers, with myself remaining as President and Dave Toth, In This Issue... VE3GYQ, becoming Vice President. Mike Lee, WB6RTH, has been selected to 1991 Financial Statement...... 2 serve as Secretary/Trcasurer. Mike has both a technical and an accounting back­ Projects Update...... 3 ground and has already become highly involved in TAPR activities. I suspect he Errata for 9600 bps Modem...... 3 assembled his new 9600 modem and TrakBox on the plane back to Atlanta because Errata for TrakBox...... 4 he had some reports and questions within a few days after the meeting. Another TAPR Announces 1.1.8 firmware new face on the TAPR scene is Lou Nigro, KW7H, our new software librarian. for the TNC-2...... 6 Welcome aboard, Mike and Lou! Advantages of a Bit-Regenerating The Board also voted to formally cancel the packetRADIO project which had Repeater for LANs...... 7 been shelved late last year, as I reported in the January issue of PSR. In addition to Notes from the TAPR Office...... 8 Notes On TAPR's new some of the problems I discussed in that report, two other factors were discussed. The cost of not only completing the design, but of purchasing parts for an initial 9600 baud Modem...... 9 UOS.AT Update quantity of kits was estimated to be such that TAPR would not be able to undertake both the packetRADIO and the DSP in the same time frame. (Yes, we are still March 10,1992...... 10 A Blow-By-Blow Account of the planning to complete the DSP. No, I am not going to predict when.) Also, the 1992 TAPR Annual Meeting ....13 situadon regarding availability of radios for use at 9600 bps has changed somewhat Software Library Update...... 25 since the packetRADIO project began. Mike Curtis, WD6EHR, James Miller, G3RUH, and others have reported that it is possible to modify many existing radios designed for voice operation for use at this data rate. New radios designed for data applications now exist. Although some have not lived up to expectations, the TEKK data radios, available from PacComm and Gracilis, and the Kanlronics D4-10 have been reported to perform quite well. Two newly-introduced radios, which are claimed to be designed for packet as well as voice, are the Alinco DR-1200T and the Ramsey FX series transceiver kits. The literature on these indicates suitability for both 1200 and 9600 bps packet operation. We hope to be able to report on these

April 1992 - Issue #46 Packet Status Register Page 1 soon. As with the new 9600 bps modem, TAPR does indeed intend to 1991 Summary Financial Statement continue to support higher speed net­ working. Tucson Amateur Packet Radio There is one thing that I can say December 31,1991 about the DSP project At the annual meeting, Jon Bloom, KE3Z, of the Assets: ARRL laboratories, talked about work Cash and accounts receivable $54,406.25 he has done with the TAPR/AMSAT Inventory $26,908.49 DSP board and was able to Rxed assets (depreciated) $5.681.60 demonstrate its operation at the meet­ TOTAL ASSETS $86,996.34 ing. Hopefully Jon’s work will inspire many of the others who are working on Liabilities and Equity: DSP software to complete their efforts Liabilities $6,296.77 and this project will now move ahead Equity $80.699.57 quickly. TOTAL LIABILITIES & EQUITY $86,996.34 For those who attended the TAPR meeting, I hope you were pleased. I Income: know that we as an organization ap­ Sales $68,423.87 preciate the support of the membership Dues $13,300.00 and I am glad that you could attend. License and royalties $2,945.00 For those who were not there, it’s not Interest $2,338.72 too early to mark your calendars for Miscellaneous $2.059.28 next year. The exact date has not been TOTAL INCOME $89,066.87 set, but there is a good chance that the meeting will occur the weekend of Expenses: March 6-7. In any case, if you plan to Cost of sales (*) $51,295.86 be at the Dayton HamVention April Operating expenses $54,092.96 24-26, come by the TAPR booth and DSP expenses (**) $187.51 say hello. We look forward to seeing TOTAL EXPENSES $105,576.33 you.

NET INCOME (LOSS) ($16,509.46) (*) Includes S 13,406.23 write off to correct inventory figures. This includes adjustment for current prices of parts as well as the sale of surplus or obsolete parts from inventory. (**) DSP is a jointly-funded project of TAPR and AMSAT, and is ac­ counted for separately.

Renew Your Membership! Packet Status Register (ISSN 1052-3626, USPS 005-419) is published quarterly by the Tucson Amateur Packet Radio Corporation, 9991E. Morrill TAPR doesn ’ t send out con- Way, Tucson, AZ 85749-9568. Membership in Tucson Amateur Packet stant reminders when your Radio, including a subscription to Packet Status Register, is $15.00 per year membership has expired. Our in the U.S. and possessions, of which $12.00 is allocated to Packet Status only way of communicating Register, $18.00 in Canada and Mexico and $25.00 elsewhere, payable in your expiration date to you, is U.S. funds. Membership and Packet Status Register cannot be separated. the date on the address label for Second-class postage paid at Tucson, AZ. this issue. Please check it and renew if required. Your mem­ POSTMASTER: Send address changes to PACKET STATUS bership is very important. REGISTER, P.O.Box 12925, Tucson, AZ 85732-2925.

Page 2 Packet Status Register April 1992 - Issue #46 Projects Update Errata for TAPR 9600 bps Modem Kit These notes should help to clear up some confusion in the TAPR 9600 bps by Lyle Johnson, WA7GXD Modem Kit documentation dated 01 March 1992. The PC board was layed out for a different input filter. As a result, there are There arc several projects which are a number of component locations on the silkscreen that are not used. There is being juggled these days. I thought it also a case of a resistor being installed in a location marked for a capacitor, and might make things easier if I just wrote of a capacitor being installed in a location marked as a resistor. There may be one article and included information extra parts packed in your kit, as the initial kits were packaged before the input on all of them. filter changes were implemented.

9600 bps Modem Finally, there has been a substitution of a different op-amp for more reliable DCD operation. This kit was introduced at the TAPR Annual Meeting. I was quite Please pay particular attention to the following: surprised by the immediate level of Page 2: interest. In fact, we were short a 1 % resistors may have a final color band of brown, not white. couple o f components and folks still Page 3: insisted on buying them and having us A TX101 transistor may be substituted for a VN10KM. ship the parts later! Page 4: After receiving a number of field There is only one (1) TL084 IC (U4). reports, an errata sheet has been Add one (1) TLC274 IC (U22). generated and sent to all owners. That Page 9: errata sheet is also included in this C22 is a 12.1k 1% resistor. PSR. A new manual is in the final Page 11: stages of editing. C13 is layed out for a polarized capacitor but uses a 0.1 uF ceramic capacitor. Plea R 12 is a 2200 pF capacitor. If you are interfacing the 9600 bps Page 14: modem to anything other than a TNC-2 A TX101 transistor may be substituted for a VN10KM. or PK232, we would like you to write Pages 16-20: to us and tell us so we can update the This section deals with the internal TNC-2 installation. The required manual to include the TNC you inter­ diodes and wires are not provided in the kit. faced. Also, if you are interfacing to a Page 17: different TNC, contact us so we can The first step on the page lists traces on the bottom of the TNC-2 PCB to work with you to determine if custom be cut at header J4. Pins 9 and 10 arc not on the list - THE TRACE CON­ U13 or U14PLDs will be needed. The NECTING J4 PINS 9 AND 10 MUST BE CUT FOR THE TNC/MODEM PLDs are reprogrammable and we’ll COMBINATION TO FUNCTION PROPERLY! do this at no charge initially. Eventual­ Page 18: ly, w e’ll offer the various PLDs as Change U22 from a TL084 to a TLC274. options at the time of purchase... Pages 21-27: This section deals with the internal PK-232 installation. The required In case you missed the last issue, the hardware, connectors and cabling are not provided with the kit. following is a brief rundown of the Page 26: 9600 bps modem kit... Change U22 from a TL084 to a TLC274. The TAPR 9600 bps modem is a Page 30: full-duplex baseband modem com­ Change U22 from a TL084 to a TLC274. patible with the K9NG and G3RUH standards. Like these modems, it re­ quires an interface to your radio other TNC to prevent, for example, keying It optionally includes a self-con­ than the microphone and speaker your 1200 baud radio when running tained clock. jacks. 9600 bps. Finally, a bit regenerator option is It uses a 4-layer PC board for mini- The receive filter includes a com ­ available for incorporating the modem mum noise, utilizes a transmit pensation adjustment to tailor the into a full-duplex repeater. Note that waveform lookup table in ROM for modem to the radio receiver and AC- this is not needed to operate as a minimum transmit distortion, and in­ coupling to accommodate frequency digipcater, nor is it useful or even terfaces easily to a variety of TNCs. drift on the channel. An improved desirable for home station use. It is The transmit path includes an inde­ state machine is used for clock solely for the purpose of providing bit pendent watchdog timer. recovery, and a DCD circuit that is regeneration for a full duplex repeater. The modem selection logic correct­ based on both signal quality and the ly routes the PTT command from the presence of a signal.

April 1992 - Issue #46 Packet Status Register Page 3 TAPR/JAMSAT TrakBox Kit The TrakBox project came from our Errata for TAPR TYakBox Kit associates o f JAM SAT in Japan. 17 March 1992 TAPR has taken the PC board from There are a few errors and points of confusion in the TAPR TrakBox kit J AMS AT, and produced a complete kit assembly directions dated 01 March 1992. (less case and external connectors). In Page 2: addition, an assembly manual has been Four (4) pieces of 47 uF capacitors may be supplied as 10 uF instead. written and is in the final editing Page 3: process as this is written. Three (3)pieces of 74HC245 or 74HCT245 should be indicated, not one The TrakBox is a self-contained, (1) piece. standalone accessory for use with Page 4: satellite stations. You simply select #4 hardware may be supplied in place of #6. Either is acceptable. the satellite you wish to track from a Page 9: front panel control, and the TrakBox C28, C29, C30 and C35 arc called out as 47 uF. Use 10 uF if supplied in­ will steer your antennas in both stead of the 47 uF called out. azimuth and elevation to track the Page 11: selected satellite when it is near or Voltage regulator may be supplied as #4 hardware rather than #6. Either is above your horizon. acceptable. The first step of Initial Check should call out CN1, not CN2. In addition, if you have a radio with Page 14: a computer interface, the TrakBox will Change the first line from "...a local indication od TrakBox..." to "...a local tune your transmitter and receiver and indication of TrakBox...". correct them for doppler shift. At the bottom of the page there is a callout for three (3) wires of the LCD TrakBox includes a serial port to • harness to be connected to CN15. There is no CN15. GND may be ob­ allow you to set the real-time clock tained at BR5. +5 may be obtained from BR4 as long as BR4 isn’t open. (which is battery backed), your station See the note about BR4 on page 13 of the manual. location (latitude, longitude, and Page 15: elevation) and the keplerian elements The wiring for the satellite selection switch specifies GND but doesn’t in­ for the satellites you arc interested in dicate where to tap it. GND may be tapped from any convenient location. (up to 40 satellites may be loaded, and In my unit, I tapped it from a GND bus that I wired across the front panel the elements may be uploaded in of my cabinet. ASCII in either the AMSAT or NASA The second NOTE: at the bottom of the page has Vcc and GND swapped. formats). Once set up, TrakBox no It should read: longer needs to be connected to any NOTE: The switch or potentiometer end near GND will select "ter­ other computer to operate. minal mode" and the end near Vcc will select satellite 15. Page 16: TrakBox includes a two-line LCD Vcc and GND are swapped on the three schematics. display showing the azimuth and Page 18: elevation of a satellite, along with the Under the section Doppler Correction using Mic Up/Down inputs, CN9 satellite ID and GMT. The display is pin 7 must be grounded for this option to work. The Up/Down polarity is updated every second. specified for the Kenwood TS-790. Other rigs may require the use of op­ TrakBox is set up to directly inter­ posite polarity. The Yaesu FT-736 requires pull-up resistors as well. face to Kenpro, Emmoto, and Yaesu dual-axis rotators which include a Other computer interface. It may also be in­ We have had one (1) report of a problem with a PC board. The PC board had terfaced to other rotators as long as a hairline crack on one of the traces. The symptom was erratic operation. If simple relays (mechanical or solid- your unit doesn’t work, or works erratically, try flexing the PC board. If flexing state) are added to the rotator control the board affects the operation, and you have resoldered all the joints, there may box. It has been tested with the KR500 be a crack on your board. Careful inspection of the area that, when flexed, most elevation rotator and the CDE/Hy- affects operation, may reveal a hairline crack. If this is the case, simply bridge Gain series of azimuth rotators (HAM- around it with a piece of wire. M, HAM-II, HAM-IV, TR-44 and We don’t expect this to be a problem as the PC boards are high quality units TailTwister styles). from a reputable manufacturer. However, we have no control over them and The radio tuning mode has been think you should be aware of the reported problem, its symptoms, and cure. tested with Yaesu FT-736, Kenwood Finally, note that when using the Yacsu/Kenpro 5400/5600 rotators BR4 TS790, and ICOM 970. It is designed. must be cut. to handle any ICOM radio with the CI-V interface (IC275, IC475. IC1275) as well as the Kenwood TS- 711 andTS-811 models. ICOM radios with the older CI-IV interface can be

P a ge 4 Packet Status Register April 1992 - Issue #46 used with an accessory convertor available from ICOM. You Can Help! An optional tuning mode that util­ If you have any other problems, find other errors, or have helpful tips that izes microphone up/down buttons is may assist others in building their TrakBox, please contact the TAPR office with also incorporated. This requires inputs the information. Writeto TAPR,PO box 12925,Tucson AZ 85732-2925 or via from a modem (PSK or 9600 bps FSK) CIS to account 76246,565 (easymail only). and is only for digital operations. This Thank you! has been tested with Kenwood and Yaesu radios. 1) The new sign-on message is: * ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ★ ■ A:*************************** * TrakBox 8052 V1.30e * The sales price o f the TrakBox in­ * JAMSAT/JA6FTL Mar.18 1992 * cludes a S25 donation to JAMSAT for ***************************************** the Phase 3D Amateur Satellite pro­ Doppler correction is now computed for every pass through the calculation gram. loop. In PSK(LSB/USB) reception, the doppler correction command is issued The current EPROM version of every time a 50 Hz difference is determined. In AFSK(FM) mode, the decision T ra k B ox is 1.30e. T A PR w ill threshold is 500Hz. reprogram your EPROM to this ver­ The real time tracking menu accepts +, - and 0 commands to assist with sion for S3 plus return postage. Be doppler compensation: sure to pack the EPROM in antistatic + adds 100 Hz to the calculated doppler frequency foam and protect it by shipping it to us subtracts 100 Hz from the calculated doppler frequency in a carton, not an envelope. Or, TAPR 0 returns to the calculated doppler value will provide an updated EPROM for S12 postpaid without returning your 3) The satellite position table includes doppler information as an offset. DATE TIME AZ / EL Phase Doppl< old one. 1991/12/15 12:56:51 131.4/ 0.4 34.9 +1650 1991/12/15 12:57:52 127.0/ 3.7 34.8 +1606 The latest level of errata and 1991/12/15 12:58:53 121.4/ 7.2 35.0 +1572 software notes is included elsewhere in 1991/12/15 12:59:53 113.3/11.3 35.3 +1536 1991/12/15 13:00:54 103.7/15.0 35.6 +1106 this issue of PSR. 1991/12/15 13:01:55 91.5/18.3 35.9 +564 1991/12/15 13:02:55 76.8/20.3 36.3 +42 1991/12/15 13:03:56 59.6/20.0 38.7 -385 Deviation Meter 1991/12/15 13:04:57 45.2/17.8 40.0 -1023 1991/12/15 13:05:57 33.4/14.4 40.5 -1245 I can offer a zillion reasons (ex­ 1991/12/15 13:06:58 24.2/10.7 41.0 -1346 cuses?) why this project isn’tready yet, 1991/12/15 13:07:59 16.7/ 6.6 41.4 -1458 1991/12/15 13:08:59 11.4/ 3.1 41.8 -1648 but the simple truth is that it isn’t. It ★ ****************** won’t be in time for Dayton, cither. -- 'Q' for abort ---- The unit is working except for 4) The Satellite Data tables now include uplink, downlink and mode infor­ tuning up the VCO buffer amplifier mation used by the CAT system. and then phase locking the VCO for ======Satellite data ======Satellite UO-14 2-meter operation. Once I get that Epoch Time TO 91 Y O : done, it will be ready for board re­ Epoch Time TO 344.21790 TO: Epoch Rev K0 9813.00000 K0: layout and "real" software (as opposed Mean Anomaly M0 345.92850 M0: to the test software now running on it). Mean Motion NO 14.29394 NO: Inclintion 10 98.65510 10: Eccentricity E0 0.00116 E0: After I get back from a lot of busi­ Arg perigee W0 14.22270 W0: ness travel (Brazil and South Africa R.A.A.N. OO 62.54790 OO: Decay N1 5.180000e-06 N1: this time), I expect to be able to dive Downlink Freq.Fl 435.07000 FI: back in and get this one off my plate. Uplink Freq.F2 145.97500 F2: Downlink mode FM Uplink mode FM DSP Jon Bloom, KE3Z, demonstrated Doppler correction CAT command is supported for KENWOOD/YAESU/ the TAPR/AMSAT DSP board at the ICOM. FI is the downlink frequency; F2 the uplink. If FI and F2 are not TAPR Annual Meeting. configured, no doppler correction command will be sent to the transmit- ter/receiver. FM, LSB, USB and NONE are the available selections for mode. Jon operated the DSP board as a In the case of Mic click Doppler correction, the FI set CAT command is issued 1200 bps packet station using the once at AOS. It is useful in PSK mode for auto tracking. KA9Q NET/NOS software package. It worked great! He also demonstrated rcceive-only RTTY and AMTOR operation on HF. He has been on the air with RTTY with it as well, but hadn’t yet finished the AMTOR transmit routines at the time o f the meeting.

April 1992 - Issue #46 Packet Status Register P a ge5 An adaptive notch filter was demonstrated, which quickly (about 10 Errata for TAPR TrakBox Kit Continued... to 15 mSec) found and notched 5) If using Yaesu CAT with a narrow FM IF filter, the FM mode should be heterodyne interference. selected as FMN during setup. In menu 6-7, you can select this option. CAT Rig KENWOOD, YAESU, ICOM (K/Y/I) ? Y Franklin Antonio, N6NKF, also Select FMN mode ? [Y/N] _ 6) The Station element information now uses signed values for latitude and longitude. Latitude: Enter demonstrated an updated version of his + for North, - for South. Longitude: Enter + for East, - for Spectrum Analyzer program using the West. DSP board as the analog front end. ======Station Element ======We had a series of meetings about Name: WA7GXD Latitude: +32.259 the DSP board. We are now trying to Longitude: -110.778 identify every hardware bug, discover Antenna height: 50.000 Rotor start (S/N): South the cause, and effect a cure. We are also looking at increasing the A/D and 7) The setup display now indicates the type of CAT control in use. The first D/A resolution to 12 bits, then turning example shows serial CAT tuning. the crank on the board for a "final" Select: 0 time. Name: NOCALL Lat: 27.4 Long: 231.3 Height: 50.0 ADC span value AZ: 8 - 859 EL: 1 - 442 The new board will be done when Dead band AZ: 3.0 EL: 1.0 Skew AZ: 0.0 EL: 0.0 we see enough progress in the software CAT Rig KENWOOD arena to reasonably expect to have’ Mic step control Not selected Rotor start South enough software to make the board Comport (fixed) 9600 8-N-l interesting to other folks. We will then spend the money and turn the crank, The second example shows mic step control for radio tuning. then release the board. Initially, it will Select: 0 likely be a kit although we will look Name: NOCALL Lat: 27.4 Long: 231.3 Height: 50.0 into the costs o f making it an as­ ADC span value AZ: 8 - 859 EL: 1 - 442 Dead band AZ: 3.0 EL: 1.0 sembled and tested unit. Skew AZ: 0.0 EL: 0.0 CAT Rig KENWOOD One nice thing for me personally Step control ADC value Center: 550 Reff: 560 about all this is that, no longer an of­ Rotor start South Comport (fixed) 9600 8-N-l ficer or Board member, I don’t have to make these kinds of decision anymore! 8) The mic click configuration menu configures the ADC value for mic click Cheers, control. When this option is selected, CAT control is disabled. Select mic click for doppler correction ? [Y/N] y Lyle Set new value or Measure ADC value ? [S/M] s Modem locked center ADC value : 550 Reference ADC value : 560

TrakBox uses full closed loop feedback for mic click doppler correction. DC error voltage from the FM discriminator or PSK modem is fed in to ADC3. If the error voltage exceeds the span value defined in this menu, an UP or DOWN pulse is generated. The ADC input voltage must be under 5.0V (=1023).

TAPR Announces 1.1.8 ping. There is also an immediate KISS command, which docs not require firmware for the TNC-2 sending a restart to the TNC. The host mode is, at this point, Thanks to the efforts of Howie recommended only for experimenters Goldstein, N2WX, release 1.1.8 of the or programmers. A disk is available TAPR TNC-2 firmware is now avail­ from TAPR for $2.00 which describes able. It provides some new features the host mode and provides a primitive and fixes a few minor bugs. There is terminal program and host protocol also a host mode included. drivers in Microsoft C source code. The EPROM is available from This disk is not included in the TAPR TAPR for $12.00, including the 1.1.7 software listing, but is available by re­ commands booklet with a supplement questing the "1.1.8 host m ode” disk. describing the 1.1.8 changes. This information will hopefully result in software written to support the host New features include QRA, where mode. an unconnected packet sent to the un- proto callsign QRA will result in an ID packet being sent by TNCs hearing the

P a ge 6 Packet Status Register April 1992 - Issue #46 Advantages of a interference with stations it was unable output and transmitter input. It incor­ to reliably detect. Bit-Regenerating porates a modem (demodulator por­ There is one school of thought tion) to recover the received data to the Repeater for Local Area which suggests that, since DCD is an bit level (digital levels, not analog or audio). These bits are then used to Networks often unreliable indicator, it should be drive a modem (modulator portion) ignored and other approaches used to arbitrate channel access. There are which then drives the repeater’s trans­ By Lyle Johnson, WA7GXD mitter. DCD is typically used to pro­ others who would couple this approach vide the PTT mechanism to the with a system allowing the TOC to Background repeater. The advantage of this is that control the transmitter power output the transmitted signal is of the proper Over the past ten or twelve years, a level to create "cells" much like a cel­ deviation, even if the received signal is number of approaches have been taken lular phone system. This approach is seriously under- or over-deviated. to the design of packet radio-based valid and is being pursued. local area networks (LANs). These Another advantage is that the However, there is another approach designs have used various protocols repeater is dedicated to the function for that is not widely used, but overcomes (polling, balanced "interrupt-driven" which it has been coordinated - packet much, if not all of the problems as­ systems like AX.25, connection- radio (orRTTY or whatever other digi­ sociated with geographic considera­ oriented and datagram styles) as well tal mode is designated for it). There arc tions. as varying approaches to "medium ac­ several drawbacks to this simple ap­ cess." Typical implementations in­ proach. Perhaps the most serious draw­ clude systems with full-duplex audio Full Duplex Repeater-based LAN back is related to clock recovery. Any repeaters, digi-peaters, single-fre­ "jitter" on the received data due to The use of a full-duplex repeater quency "networks" and various ad-hoc noise will be retransmitted. If the brings a significant advantage to local combinations of all of the above. received signal is marginal, the trans­ area network communications. In this paper I will attempt to outline mitted signal will automatically be at a cost-effective, spectrum-efficient It virtually eliminates the "hidden least as marginal. Thus, if you have a method of network implementation at station" effect. If the repeater can hear less than optimum path to the repeater, the local level. a transmission, then every station that you will have a difficult time decoding uses the repeater can hear the station. signals from other marginal users. The Media Access Thus, DCD can be used as.a reliable bit-regenerator can be enhanced to Media access is a term used to indicator of channel occupation. overcome this primary difficulty. A describe the method by which a packet The geographic coverage of the first-in first-out (FIFO) buffer can be radio station determines that it may LAN can then be tailored by repeater incorporated to collect some number of safely transmit data, and how it deter­ location and antenna configuration received bits, then deliver them to the mines if the data it sent was successful­ (use of downtill, broad lobe beam an­ transmitter. This buffer acts somewhat like a rubber band, stretching and ly received by the intended recipient. tennas, etc.). Repeater-based LANs shrinking as needed to keep the trans­ Most packet radio modems in com­ can then be networked using another mitter happy. In this manner, clock mon use provide a data carrier detect frequency, or combination of frequen­ jitter is completely removed by use of (DCD) output. This signal is used by cies, to implement an efficient network a crystal-controlled clock on the trans­ TNC software to determine if the topology. mit modem. The buffer must be deep modem’s bits are worth decoding The usual objection to the use of enough to allow for variations in the (valid signal) as well as to determine if repeaters is that they require duplexers, speeds between various modems the channel is occupied by another sta­ and duplexers are several hundred dol­ (usually well under 0.1%). For tion, in which case the TNC will defer lars, so repeaters shouldn’t be used. Amateur packet radio needs using its transmission. However, in many cases single-fre­ AX.25 protocols, or any other protocol There are fundamental problems quency "digi-peaters" areco-locatcd in where the number o f bits in a given with this general approach. In some intense RF areas and require the use of transmission is under about 20,000, a cases, a station may be able to hear RF filters as well. And, "node stacks" 16-bit deep FIFO filled to 8-bits before distant stations (a hilltop location, for typically combine several RF transmit­ transmission occurs, will easily suf­ example) and the DCD will cause this ters and receivers in close proximity, fice. transmitter to defer forever, even also requiring RF cavities and/or though its transmissions might not duplexers. Other Potential Advantages cause any problem to the distant sta­ The use o f a full-duplex repeater The implementation of a bit- tions operation (which may be com ­ can be significantly enhanced with the regenerator on the TAPR 9600 bps munications with a nearby station at addition of a bit regenerator. modem has other advantages that may the distant location, for example). be exploited by future TNC firmware. Or, the station’s DCD circuit may What Is A Bit Regenerator? If the bit regenerator/modem is at­ be implemented poorly, allowing In its simplest form, a bit tached to a TNC, the TNC PTT will transmissions to occur and generate regenerator is a device which is inter­ override the FIFO buffer output. This posed between the repeater’s receiver would allow, for example, a nodestack

April 1992 - Issu e #46 Packet Status Register Page 7 using a full-duplex bit-regenerator put from the repeater. A transmission great funds, so they stayed at a camp­ repeater to "grab the channel" in case could be sent to a station running with ing spot near the beach. Arriving at the of an emergency or for administrative too much deviation, asking him to convention with less than the latest purposes. At the same time that the reduce his deviation. Or an automated appearance, but definitely the latest TNC is sending its data, it will still be deviation reporter could be imple­ technology, they proceeded to share. receiving the uncorrupted transmis­ mented, providing a community Before leaving the convention, the sion from the station which was being resource for getting the deviation set ranks had swollen to 250! regenerated. Thus, the received data is properly. Finally, a bit-regenerator From my point of view, there are not lost and may simply be delayed if makes a full-duplex 9600-bps (or many reasons why the movement the proper firmware is available for the faster) local area network not only grew, and outstanding things were ac­ TNC. feasible, but easily do-able. Hopefully, complished. First, there was fulfill­ the availability of the TAPR 9600 bps Another application, also requiring ment in contributing,making a mark. modem with its bit-regenerator specialized firmware, is that of chan­ There was tremendous satisfaction in capability will encourage the growth nel-use enforcement. Enforcement is learning, comparing notes with other o f such higher speed LANs. a strong word to use in the Amateur skilled, knowledgeable hams, and context, but consider the following Conclusion together contributing to the fur­ scenario. Assume a bit-regenerating therance o f our much loved and ap­ A bit-regenerating full-duplex repeater is being used for a local area preciated hobby. Enthusiasm breeds repeater offers many advantages when network, and that specialized firmware more of the same, so before we knew implementing a local area network. It exists on the attached TNC. Further it, we had outgrown our ability to keep allows existing TNCs and radios to assume that a local user comes on fre­ it a completely volunteer group. A work in a coordinated fashion, defines quently during "prime time" and secretary was hired to handle the in­ a geographic area of coverage and refuses to set his TNC’s parameters to creasing phone calls, and now TNC removes hidden stations within that share the channel in accordance with orders. area o f coverage. It offers oppor­ locally agreed upon guidelines. tunities to encourage technically and Not everything was easy, glorious, Maybe this user likes to transfer socially sound usage patterns for the or wonderful. Liberal amounts of oil megabyte files and sets DWAIT to 0, shared spectrum resource. were needed. Oil you may ask? Yes, persistence to 255 and FRACK to 1. the oil o f understanding and working He is a hog. After repeatedly asking • Notes from the TAPR together when personalities or ideas him to change his patterns, the system were in conflict. Finances were a prob­ administrator simply logs this station’s Office lem, and if it had not been for the callsign into the "lock out" list on the generosity of Lyle’s employer, TNC. Now, whenever this callsign is Ten Years... Modular Mining Systems, who fronted detected by the TNC, the TNC simply TAPR with many tens of thousands of asserts its PTT for 10 mScc and the It Hardly seems possible that a dollars, the effort of making available repeated transmission is corrupted. decade has passed, and yet it also feels TNCs to the Amateur community at Thus, the channel abuser is prevented like a millcnium ago that Lyle first large would never have been realized. from using the machine. When he came home from an IEEE meeting amends his ways, his call is removed VERY excited about a new mode of It is for our Amateur radio history from the TNC’s blacklist and he can communication. At the time, I was still books to document all that was ac­ share the channel resource with working with Mr. Bash, trying to un­ complished. From an observer’s view- everyone on an equal basis. derstand the very basics of radio, so, point,bcsides furthcringPackct Radio and infusing additional life into our To implement this, the TNC would although I tried to sound fascinated, it hobby for the many individuals in­ simply check for the "FROM" call all went completely over my head. volved, it has been a growth o f spirit field in the packet as its is being Soon, I met the gang of ’True En­ and self. Instead of simply being one received. There is no need to wail for thusiasts,’ led by Den Connors, and of the many pebbles on the beach, these the CRC! If the incoming packet is everything started to escalate. Den was contributors are the pebbles that the decodable by anyone, the address an initiator, and thought big. Lyle was child chose to pick up and take home header will be received correctly. If it a brilliant, and energetic worker. as treasures of the outing. is correct, then the PTT assertion can Everyone was enthusiastic. occur prior to the CRC to ensure the Because the job o f giving credit to The group of six soon became 60. It packet is "locked out." If the header is whom credit is due is a monumental misinterpreted due to noisy reception, was an exciting time of multiplication. job, and one that must be complete or Why were so many people joining the then the bit-regenerated packet will be else is not satisfactory, I simply ask ranks, you may ask? Because, here was exactly as corrupted, and the packet each of you that reads this, that knows a group o f people sold on what they would be rejected by all listening sta­ better than anyone else, the efforts and tions anyway. Thus, the enforcer were doing, and willing to put muscle sacrifices that you made, to please pat mode is technically feasible. Or, as­ behind it. Men of vision are always yourself on the back, and take it from sume that a METCON unit is attached followed. me that you have contributed to a job and it is monitoring the deviation of HamComp 82 (San Diego). The well done. incoming stations via the detector out-. group from TAPR had drive, but not — Heather Johnson, N7DZU

P a ge 8 Packet Status Register April 1992 - Issue #46 On TAPR’s new 9600 available, and c) it’s supported. That bandwidth o f 1.2 times the data rate. is to say, people get 100% answers to For the TAPR modem, the figure is 1.7 baud Modem their technical questions, in full, same times, i.e. 42% wider. These are AF day, every day, world-wide. spectra. The RF spectra are similar for a given deviation. by James Miller G3RUH "The G3RUH design is fairly ex­ pensive." The TAPR bit shape depends only The article entitled "A New 9600 on the "now" and "previous" bits, i.e. 2 TAPR sell kits. As far as I am bps Modem" by Lyle Johnson bits. The G3RUH transmit waveform aware the G3RUH modem is only WA7GXD in TAPR’s Packet Status depends on 8 bits (or even twelve), four available as built, not in kit form. So Register issue 45, Jan 1992 contains a on each side of "now." This look­ the comparison is not valid. number o f unintentional misrepresen­ ahead and look-behind convolution al­ tations about which I would like to "The G3RUH design... attempts to lows tremendously fine control o f the comment. Direct quotations arc in pre-distort a transmitter’s output to transmitted bit shape and spectrum, double quotes. match the distant receiver. The trans­ and accounts for the m odem ’s un­ mit bandwidth becomes wider than rivalled performance. "A couple of years back G3RUH necessary as a result o f the non- made a modem with a number o f im­ "You have to know all about the linearities in the overall transmit trans­ distant receiver beforehand..." provements and this has helped to spur fer function." interest." May be true in theory, but not a This is not so. The new TAPR In fact the G3RUH modem has been restriction in practice. I have tested design uses a raised cosine bit shape at scores of radios. As it turns out, group in full scale production since May the transmitter. The G3RUH fun­ delay is rarely a problem. The limiting 1988, nearly four years. I have per­ damentally uses a raised cosine factor is usually the receiver’s sonally supplied 2000 cards, 70% SPECTRUM. These two are strikingly baseband roll-off at 4800 Hz and abroad (i.e. not UK). Licensed sup­ compared in the diagrams 7 & 9 pliers include PacComm, Kantronics, above. But most radios use very reproduced from [1], One figure similar FM receive circuitry, and we Tasco Japan (the world’s largest TNC shows the TAPR raised-cosine bit maker), Gracilis, MFJ, BayCom and find that EPROM selection number 10 shaping, eye diagram and spectrum, five others. They account for nearly covers almost every case, including in the other the G3RUH modem charac­ particular the UOS AT -14/22 satellites. 3000 more. What has "spurred inter­ teristics. 99.9% o f the G3RUH bit’s est" is the fact that a) it works, b) it’s energy is contained in a (two-sided)

P age 9 April 1992 - Issue #46 Packet Status Register Every communication system is UOSAT Update the cure; a single copy of the directory bandwidth limited. Sometimes this sent in such a way that all stations limit is under our control, sometimes March 10,1992 could receive it simultaneously and up­ as here, it’s a given. In either case, for date their own copy o f the directory. the best signal-to-noise pcformance by Jeff W. Ward, G0/K8KA Harold (NK6K) and I had always the optimum split of the spectral shap­ wanted this feature, but in November University of Surrey ing is half in the receiver, and half in and December it went right to the top the transmitter. In this 9600 baud FSK Centre for Spacecraft Engineering of the user wish list. data transmission environment, FM Research I managed to get the broadcast receivers actually have the RX "half directory feature and some ground sta­ [Reprinted from the April 1992 (#94) implicit. The other "half" should tion software support implemented in therefore be explicitly provided at the issue o f the OSCAR News, published byAMSAT-UK.] the week before Christmas, so a new transmitter. The precise bit-shape version of PB.EXE for the ground sta­ tailoring implemented in the G3RUH' There have been a lot of changes on tions and a new version of the modem achieves this. This is known UoSAT-3 and UoSAT-5 since I last Housekeeping Integration Task (HIT) as "matched filtering." reported to you. Some of the changes for the satellite were set to work just Finally, a plug: Ref [1], which has were in response to user requests and when I left the country for a couple of to date been printed in six magazines increased loading of the store-and-for- weeks. ward transponders, and some of the and three languages, contains material The change was well-received, changes were caused by other pres­ about "bits, bauds, and bandwidth" that even though the ground station code ought to be as familiar to every ham as sures on the UoSAT unit. had a few hidden "features" and the is Ohm’s law! Broadcast Directories satellite software wasn’t really fully debugged until mid-February. The Ref [1]: J. Miller G3RUH, "The During the closing months of 1991, new release of PB, as well as support­ Shape of Bits to Come," The AMS AT UO-3 users were complaining bitterly ing the broadcast directories, has a Journal, Vol 14, No. 4, July 1991 pps (and not without reason) that they had 12-19&30. (Also in Proceedings 10th point-and-shoot directory viewer, to wait in line with dozens of other automatic downloading o f messages, ARRL Computer Networking Con­ users each day just to connect to the and some other niceties. ference, 1991, pps 112-120). FTL0 server and download a directory James Miller G3RUH @ o f messages on the satellite. Even The activity log output shows that GB7DDX.#22.GBR.EU & UO-22 though everyone wanted pretty much the broadcast directories are doing the same directory, each person had to their job. In November 1991, directory connect and get their own private copy. downloading represented 60% of Clearly, a ’broadcast directory’ was FTL0 activity on UoSAT-3; by

Page 10 Packet Status Register April 1992 - Issue #46 seem to notice, but the UO-5 modula­ tion signal is a bit deficient on the low-frequency component. Some receivers (presumably those with al­ ready poor low-end performance) receive UO-5 considerably worse than they received UO-3. The modulation gurus arc hard at work trying to come up with a fix so that everyone can regain the low bit error rate that they had on UoSAT-3.

The Broadcast Queue It’s not always nice to be popular. As soon as we got the broadcast direc­ tory server working smoothly, and everyone moved over to UO-5 (where we could have 800 active files), the February 1992 it had been cut down to UoSAT-5, and all non-Amateur traffic satellite downlink started getting full. about 25%, and was still falling as on UoSAT-5 move to UoSAT-3. There were only 10 slots in the file users switched to broadcast-directory- broadcasting queue, and over Europe To the Amateur users, who had compatible software. O f interest, the and the USA these slots were com ­ been freely using BOTH satellites at other figures for November show pletely full for entire passes. Frustrated near 100% duty cycle, this was a sud­ about 10% for downloading and the users started holding down the "repeat den loss of bandwidth. Of course, the remaining 30% for uploading. For send" key and cluttering the uplink. 100% use of UoSAT-5 by Amateurs February, 10% downloading; 25% Whenever a slot came open in the wasn’t permanent anyway; SatelLife directories; 65% uploading. Clearly, queue, 10 or 20 stations were piled up would have been taking up more than we are moving toward the "ideal" state to get it. half of UoSAT-5 bandwidth once their in which FTLO will only be used for network was up and running. But it still There are a couple o f long-term uploading. The graph shows the seemed a shame to lose the two-satel­ cures for this problem, but we decided monthly breakdowns for each type of lite system. to go for the quick fix before the "R” FTLO activity (based on number of key addicts spoiled everyone’s fun. On Everyone seems to have moved bytes uplinked or downlinked). March 5th we uploaded a new version over to UoSAT-5 without great of HIT with 20 slots in the broadcast Switch to UoSAT-5 (OSCAR-22) problems, and the "old" network is up list, and then on the 6th we turned down Early in February, after a lot of con­ and running on a new bird. We haven’t the slot time to five seconds. This sultation and planning, we removed been taking as many CCD camera pic­ means that more people can get into the UoSAT-3 (OSCAR-14) from Amateur tures as we used to, but there have still list, and generally there aren’t very service and placed UoSAT-5 been some stunning shots returned m any "N O -1" p a ck ets on the (OSCAR-22) wholly into the Amateur since the "big switch." Thanks to downlink. Satellite Service. Although we had everyone for putting up with the con­ planned to keep both UoSAT-3 and fusion and inconveniences o f the The faster queue rotation time of 5 UoSAT-5 partially Amateur and par­ move. seconds combines with the "queue tially non-Amateur, this plan has run jump" fix to make the satellite quite into two difficulties: The UoSAT-5 UoSAT-5 Downlink Modulation responsive despite high loading. The CCD camera has proven very success­ The switch to UoSAT-5 has its ad­ "queue jump" fix was done sometime ful, and Amateur radio stations around vantages; there is a 13 Mbyte RAM in late February, and it gave broadcast the world are downloading the images disk (versus 4 Mbytes on UO-3) and priority to any request oflcss than 1024 of the Earth; images arc taken several there are 512 Kbytes of program RAM bytes. This means that for short mes­ times per week, and each is more than (256K on UO-3). The additional space sages, or for gelling the last few hole 300K bytes o f data. Furthermore, has allowed use to increase the active fills in a message, you don’t have to UoSAT-5’s high power amplifier — file limit to 800 files, overcoming some wait behind 20 other people to get your which has produced excellent output the "PACSAT file system full or wish. on the Amateur frequencies — does broken" messages seen by UO-3 users I hope that these fixes help keep not work reliably on the non-Amateur in January. things running smoothly for a couple frequencies. Unfortunately, there are also some o f months. As we get nearer to the Taking into account the resources drawbacks to UO-5. The conflict be­ launch of KITSAT-A in July, w e’ll available to us and our obligations to tween CCD camera users and mailbox have less and less time to alter the SatelLife, AMSAT-UK, and other or­ users has already been noted. Another current flight software. After the KIT­ ganizations, we decided to have all problem is the spectrum o f the UO-5 SAT-A launch, I want to implement Amateur traffic on UoSAT-3 move to downlink signal. Some receivers don’t

April 1992 - Issu e #46 Packet Status Register Page 11 some fairer algorithms for choosing limited, and we’ll eventually hit the you with messages getting trapped on who gets the FTLO and PB slots. limit. UO-14. The switch to UO-22 has two In the mean time, make the most When we do hit it, the programmers important advantages that we should keep in mind: efficient use o f what w e’ve got. If will do their best to keep up a you’re a PB user, take advantage of the reasonable service. By limiting the 1. More directory entries — 800 to broadcast protocol. Don’t mark a mes­ number of stations uploading at any be exact. This means that messages sage "n" unless you are really NEVER one time, we’ve already avoided the will have longer lifetimes, and we can going to want that message. Leaving catastrophic collapse that would occur consider upping the default lifetime to things marked "g" doesn’t mean that in a purely anarchic (ALOHA) net­ seven days for bulletins, while recom­ you’ll waste satellite resources; on the work. In the future, we’ll take steps to mending shorter lifetimes for other contrary, it means that you’re making make sure that our limited facility isn’t mail. (A release of PFHADD is re­ the best use of the broadcast protocol. monopolized by one powerful user in quired, I know). O f course, unless we Use "a" and "p" for messages ad­ each footprint, and try to make sure fill up to 750 message, the lifetimes dressed to you, and any bulletin you’re that gateways and private stations will not particularly matter. in a hurry to complete. share equally. 2. More uplink channels — Be­ Whether you sec these measures as cause we are not supporting non- LATLON Project successful or not will depend on what Amatcur activities on UO-22, we can I mapped the responses to the sta­ you see as "reasonable service." If you switch both receivers to AMSAT tion location request posted several want an "OK" packet every lime you uplink channels. I would recommend months ago on UO-3 and UO-5. The makca request, you’ll be disappointed. that we try to concentrate uplink ac­ maps below clearly show the areas of You might even be dissappointed if tivity on what was the old UO-14 highest activity. you expect to get down your personal uplink, 145.975 MHz, and use 145.900 mail on the first pass every Saturday MHz for overflow. This reduces inter­ ference on 145.900 to AO-13 users and the microSATs. I think that the best way to divide uplink activity is to have broadcast requests and other PB opera­ tions on .900 while uploaders are on .975.1 know that this would be difficult for automated stations, and don’t ex­ pect everyone to comply. On the other hand, if manned stations try to do it, then it will improve performance for everyone. There are still several outstanding matters that I have to sort out:

Does it Work? morning. The design goal for the sys­ 1. PB new release with fixed SLIST Whenever the satellite fills up (in tem isn’t instant gratification, it’s and archiving of PFHDIR.PFH another novel, yet partially-expected gratification averaged over 12 or 2. PFHADD new release with user- way) there arc some users on the phone maybe 24 hours. You should get your entered EXPIRE.TIME wringing their hands claiming "they morning mail in the morning and your Coherent FILE_TYPE (particularly can’t communicate with UoSAT." evening mail in the evening. file type 12!) Don’t get me wrong, I like to hear from I hope that everyone can be happy you, but I think it’s worth re-stating 3. Reduction of redundant broad­ with this definition of "service." The what I expect from the system, so that cast transmissions (flight software alternative is to make sure that you can judge your own expectations. change) everyone gets something down on First, there is only limited capacity every pass, degrading performance to There are technical matters which available. There are X seconds of an equally poor level for all users. I will require input from others at UoS downlink and uplink time which must must say that a (nameless) member of or within AMSAT: be shared by all N stations in a par­ the development team has always held 4. On-board image compression for ticular area. If the number of stations that "hams would rather have 1% of a CCD camera doubles, we might expect that we littler pie NOW, than 10% of a bigger Power management software to allow would lose half of our individual pic tomorrow," but we’ve resisted the HPA opertion. capacity. Fortunately, most people arc temptation to let all the users slug it out reading bulletins or other multi-des­ in ALOHA-land. All of this will get "medium" tination messages; with the broadcast priority, with high priority reserved (in protocol, we don’t immediately need • Welcome to UO-22 my case) for the KITSAT-A mission one "unit" of new bandwidth for each I hope that the rapid switchover which is moving into the flight new user. Nevertheless, the resource is hasn’t inconvenienced too many of hardware stage.

P a ge 12 Packet Status Register April 1992 - Issue #46 A Blow-By-Blow into a data scrambler, to the transmit Answer: It hasn’t been tested, but it waveform ROM lookup table, to a should work. The op amps and the Account of the 1992 digital to analog converter, through a ROM lookups are plenty fast The TAPR Annual Meeting filter, and out to the radio. The clock input analog filter would have to be can be obtained from the modem dis­ adjusted. The transmit lookup table connect, or generated on the 9600 baud might help at higher speeds to com ­ by Paul Williamson, KB5MU modem board. RTS from the TNC pensate for the nonlinearilies o f a controls PTT through a watchdog and wider filter. We should try that ex­ [ From the SANDPAC Newsletter! an LED indicator. Programmable periment logic provides switching from the 9600 The following is based on the notes Question: Has it been tested on the baud modem to the TNC’s internal I took during the TAPR annual meet­ satellite? How does its perfor­ modem. It is still necessary to hook up ing. Any mistakes are mine. On no mance compare to the G3RUH? account should you assume that this the modem directly to the dis­ account represents the official position criminator and modulator inside the Answer: It hasn’t been tested on the of TAPR or anybody else. But I hope radio, not to the speaker and satellite yet. Lab bench tests aren’t you find it interesting. microphone jacks. realistic, but they show that the new modem is no better than the A block diagram of the Lyle Johnson. WA7GXD G3RUH, and 1 to 2 dB worse under demodulator portion of the 9600 baud some conditions. TAPR’s New 9600 Baud Modem modem was displayed. The input buff­ What It Is, What It Isn’t er has a high input impedance, 100 Question: The PK232 limits the TAPR’s new 9600 baud modem is kohm or more. A Buttcrworth 6kHz TB AUD (computer to TNC) rate to compatible with existing K9NG and filter is twcakable to compensate for 9600. Does this cause a problem G3RUH 9600 baud modems. It’s an the frequency response of the receiver, when using the PK232 with a 9600 inexpensive kit, capable of full duplex which is especially useful with rigs baud modem? operation (like the G3RUH but unlike with LC filters like Mitreks. The data Answer: We haven’t noticed any the K9NG), with improved DCD (data slicer feeds a descrambler, state problems in testing. Probably the carrier detect) performance and clock machine and DCD circuit, with an out­ worst thing is that you won ’ t be able recovery. It looks up the transmit put for a bit error rate test. The DCD to keep the pipe completely full on waveform in ROM, like the G3RUH, detects synchronous transitions, rather transmit, resulting in dead time. and has a frequency response compen­ than the lack of asynchronous transi­ On the PK232, the sation adjustment on the receive side. tions as before. ALTMODEM 1 command permits The board is designed to mount inter­ Block diagram of the bit the user to switch to the 9600 baud nally in a TNC-2 (where it’s a tight regenerator. It consists of a PAL and a modem from the keyboard. This squeeze) or a PK-232. The board in­ FIFO chip. The FIFO inserts a means you effectively have a third cludes provisions for bit regeneration nominal delay of 8 bits, and is required radio port, because you can leave (parts optional) for use in a full duplex to eliminate bit jitter and timing errors digipeater. the PK232’s two existing ports in the received signal. The result is hooked up to other radios. There arc about 5000 G3RUH that if the repeater can copy the input TXDelay (delay between PTT modems in service overall. Heathkit is signal at all, it will transmit a perfect and first data) is another issue. If mostly out of the kit business, so one signal. A diagram of the switching you have the state machine DCD o f the goals of the 9600 baud modem configuration shows how the bit regen project was to leverage TAPR’s exper­ is connected with the TNC, so that the mod kit in your PK232, there’s a tise at packaging kits to make available TNC can transmit on the channel in­ small extra delay that requires in­ a 9600 baud modem with better perfor­ stead of the bit regenerator. creased D CD at the other end. With a TNC-2 or a Kantronics mance lhan the K9NG at a reasonable A sample of the 9600 baud modem price. The design addresses problems DataEngine we could run TXDelay was passed around the room. It’s a o f 1 or 2. with the K9NG modem (like its half four layer PC board, which helps cut duplex design) and adds features for the RF noise. It’s relatively compact, Question: Has the modem been tried at network builders (like the bit but it has a lot of parts on it. The 4800 baud on the 6m backbone? regenerator). The state machine in the documentation shipping today is Answer: No. K9NG could mistake silence (like a preliminary, and needs more informa­ Dewavne Hendricks. WA8DZP squelched radio or a weak carrier) for tion on hookup to various TNCs and a data carrier, thus holding off trans­ radios. Updated documentation will mission indefinitely. The new state be sent to early buyers. Use of CDMA Spread Spectrum machine design cures that problem, in the Amateur Service and also gives better clock recovery. Question: I’m interested in higher Last year at the TAPR meeting, we speeds than 9600. Is this modem talked about Part 15 spread spectrum A block diagram of the modulator planned to be scalable to higher (SS) communications systems, and portion o f the modem was displayed. baud rates? The modem disconnect header (TAPR displayed a low-cost commercial product capable of high data rates. The standard or PacComm extended) goes

April 1992 - Issu e #46 Packet Status Register Page 13 A Blow-By-Blow Account of the proponent of spread spectrum, and he before the STA ends. Then hope that 1992 TAPR Annual Meeting. was interested in the Amateur manufacturers will go after the ham continued...______proposal. He assigned a staffer to the market. We haven’t done a good job year before that, N3FCT presented a STA. The STA requested a two year o f keeping the FCC up to date. We paper on license-free spread spectrum. authorization for any spreading code need to tell the FCC where the public Folks in the San Francisco Bay area on any VHF or higher band. Before the interest lies. The FCC wants to help, were inspired to look at the Part 15 STA could be approved, the staffer had but we have to play the game: STAs, market. The results o f a Field test of to get every agency involved with the Part 15, waivers, and so forth. units from Proxim was posted on use of any of those bands to accept the Question: Is all the Part 15 activity at Usenet. One watt into a 6 dBi antenna proposal. It was a lot of work, but with 900 MHz? gave 2 miles LOS tested and 8 miles support from Stanley and the League it LOS predicted at 121 kbps. There’s was done. The STA was granted. Answer: No, we’re not using 900 MHz been lots of activity in the wireless at all. We are currently working at There are plans for tests in at least LAN market and at the FCC since then. 2.4 GHz, and have plans for 5.7 the Northern and Southern California We wanted to find out why the amateur GHz. areas. People interested in serious ex­ radio service isn’t using spread perimentation with spread spectrum Fried Hevn. WA6WZO. spectrum techniques, and approach the can be added to the STA. The inten­ FCC for whatever rule changes are tion is to eventually submit a Petition ARRL Southwestern Division needed. An STA (Special Temporary for rulemaking to get a better set o f Director Authority) for testing was sought and spread spectrum rules. The restric­ Read the Division newsletter for obtained. tions on spreading codes and the re­ more about what’s going on. Some A second generation Proxim unit quirement for narrowband station ID high points: There’s a bill in Congress was passed around. It is a 121 kbps are particularly onerous. that can protect Amateur frequencies data radio (data in, antenna out) in a from further erosion. A big effort One lest is starting in San Diego, funded by the ARRL membership was very liny box. In the OEM package for under the California State Library laptops, it costs $50. The internal directed to preserving Amateur project for packet radio. Using radios modules of the Proxim radio were dis­ spectrum at W ARC-92. The results produced by SRI, the project will inter­ played - all very tiny. Computer are not final yet, but it appears that no connect libraries to the wide variety of manufacturers are starting to put these Amateur spectrum was lost at the con­ online databases available via the In­ directly into laptops for wireless LAN ference! The 1992 ARRL National ternet, without the cost of a 56kbps use. Challenge to ham radio: get coor­ Convention is at the Los Angeles Air­ landline connection to the Internet. dinated with the computer BBS folks port Marriott. The pilot project in San Diego is spon­ and build a wireless Internet. sored by Apple Computer, and radios Jon Bloom. KE3Z The ARRL Spread Spectrum Hand­ have been donated by Tethcrlcss Ac­ book is good for a basic tutorial and for cess (Hendricks’s company) and by TAPR DSP Project Report historical information on spread hams. Parts o f the neLwork are KE3Z received one of the first set spectrum. AMRAD did the experi­ operated under Part 15 (license free), of beta test DSP boards from the ments that led to the current rules per­ Part 97 (Amateur), and Part 5 (ex­ hardware designer, Lyle Johnson. mitting spread spectrum. The present perimental). Procrastination set in: the board has rules are like handcuffs. In particular, over 2000 holes, so assembling it is a Funding has been allocated in the they mean that Amateurs won ’ t be able bit of work. Finally, got it assembled. Bay area to connect 100 libraries from to use commercial spread spectrum The next step was to learn about how San Jose to Roseville, San Francisco to products, because they don’t happen to to do DSP programming. Highly Sacramento, all in one WAN. Part 97 use one of the few spreading sequences recommended: the Computer Literacy (Amateur) radios are to be used for permitted by the rules. We decided to Bookstores in and around San Jose. long haul links, and Part 15 radios for seek a rules change. This turned into a Good books for techno-weenies, in­ intra-city links. This experiment will long process. It turns out to be impor­ cluding some on DSP. last through the end of the year. Phase tant to use connections in rulemaking II will involve redesigned 1.5 Mbps Some preliminary DSP applica­ matters. After last year’s meeting, radios and associated networking tions are already written and working. Paul Rinaldo, W4RI, at ARRL HQ was software. Currently the project sup­ A Bell 202 (1200 bps AFSK, like on approached for, and arranged, ARRL ports only Macintosh computers, part­ 2m packet) modem is up and working, cooperation for an STA submission. ly because any Mac off the shelf can with a driver for KA9Q NOS for pack­ After several months, and polishing by handle up to 900 kbps data links. et use. A RTTY modem (2125/2295 the League lawyers, the STA applica­ Hams in northern and southern Hz AFSK) with a RTTY driver and tion was submitted to the FCC, which California will be seeded with equip­ receive-only AMTOR driver is work­ promptly sat on it and did nothing. ment to try out Phase II. ing. Dave Hershberger, W9GR, has About this time, the League written two audio-in/audio-oul Filter There’s a lot of work to do. First, managed to get FCC Chief Engineer programs. One notches out tone inter­ get the FCC rules changed. That will Stanley to speak at the Computer Net­ ference from the audio channel, and take 1 to 1.5 years, on the fast track. It working Conference. Stanley is a works great. The other tries to remove is hoped that the rules will be changed

P a ge 14 Packet Status Register April 1992 - Issue #46 A Blow-By-Blow Account of the traction. The lowpass filter is another and that version will be ported (or 1992 TAPR Annual Meeting. cookbook design. That’s it. Notice the rewritten) fortheTAPR DSPboard. continued-______absence of any higher math in this We may want to rewrite rather than noise from a SSB signal, and needs description. This isn’t the optimum port Dalanco-Spry applications, be­ more work. These filters were demodulator, but it’s as good as most cause the subset of instructions sup­ originally written for a TMS32010 analog designs, and it works. ported by that processor was pretty board of his own design, and have been brain-damaged compared to the in­ A similar approach was tried for the mechanically ported to the struction set o f the TMS320C20 Bell 202 demodulator, but for un­ TMS320C20 on the TAPR DSP board used on the TAPR DSP. The AEA known reasons it didn’t work very (so they aren’t optimized for it). box contains a Motorola 56001 well. A Bell 103 modem was taken DSP processor. Its modems are su­ The lesson is that DSP software from another ap-notc, based on a dis­ perb compared to analog modems. isn’t necessarily magic anymore. It is criminator design: the audio is delayed quite possible to write working modem by 90 degrees and mixed with itself, Question: What sampling rate can software, for instance, without getting then lowpass filtered and compared to DSPs handle? zero. The Bell 202 demodulator is just heavily into sophisticated mathe­ Answer (W3IWI): The Dalanco-Spry matics. The basic building blocks are this design, tweaked up for Bell 202 board could do a spectral display at tones and bit rate. simple, and design tools exist to handle 50 KHz. filter design. The book D igital Signal Processing Answer (KE3Z): It’s been suggested Experiments by Alan Kamas and Ed­ Coming attractions: that we can just digitize the antenna ward A. Lee contains a diskette with • Bell 103 modem (HF packet) voltage. • 1200 baud PS K for Pacsats educational versions of Burr-Brown • 9600 baud FSK DSP design tools, including the tool Answer (W3IWI): Unintentional (K9NG/G3RUH/TAPR com­ that generates coefficients for FIR fil­ radiation can be a problem. The patible) ters. The book is quite inexpensive DSP processors can generate a lot • Spectrum display 4800 baud PSK (about S21) for a DSP tool set. It’s of crud. for Pacsat - the satellite has never published by Prentice-Hall; recom­ Answer (KE3Z): The TAPR DSP [ISBN 0-13-212853-5] been in this mode, since no user mended. board is pretty well decoupled. modems have ever been built. Both DSP programmers and PC ■ 2400 bps Kantronics-style programmers are needed to work on • improved W9GR "dc-noiser" fil­ applications for the TAPR DSP Bob Nielsen presented an award to ter project. The PC level programmer Chuck Green, N0ADI, for his out­ • weather fax sees an environment much like a DSRI standing contributions to the develop­ • slow-scan television board plugged into a PC. Contact Jon ment of packet radio through ten years Some of these applications exist for Bloom if you’re interested. of TAPR. Chuck accepted the award, other boards, and just need to be ported but claimed that it represents the team­ to the TAPR board. Others need to be Tom Clark, W3IWI, spoke up: The work that goes on behind the scenes written from scratch. Many of these TAPR DSP project grew out of earlier everywhere. applications will be implemented over development on the Dalanco-Spry this spring and summer. PC software Model 10 DSP board. About 30 of Pete Eaton held the drawing for to support the applications, is also these boards were purchased, and door prizes, then the meeting broke for needed. NOS is nice for some packet probably some could be made avail­ lunch. applications, but other applications able to new interested people. Lots of Mike Parker. KT7D need other PC software. applications were written for the Dalanco-Spry board, and they’re all The Radio Workstation Concept A virtual-hardware block diagram available for the grabbing on tomcat o f the RTTY demodulator is shown. Block diagram: Antenna con­ (Tom C ’s AT) by anonymous FTP via nected to analog radio, connected to a It’s just two bandpass filters running Internet, or by telephone, or by floppy into detectors, followed by a com­ digital sampling and output box, con­ disk if necessary. Another application parator and lowpass filter. Standard nected to a general purpose worksta­ that’s needed is a good adaptive HF tion. stuff. modem (along the lines of Clover II), DSP-oriented block diagram of the and HF protocols that can use them. The problem with DSP software is RTTY demodulator. The bandpass fil­ AX.25 sucks on HF. AMTOR has that it’s so difficult to write for special- ters are straight out of a manufacturer’s problems, too. Pacsat broadcast purpose DSP processors. By the time application note. The coefficients for protocols arc a bit like what’s needed you’ve finished writing the software, the filters are computed by a computer for an HF protocol, but it needs chan­ the special-purpose DSP processor program, so no heavy math is needed. ges for the HF environment. you wrote it for is obsolete. Worse, by The filter design is an 80-tap FIR that time your general-purpose Question: Who is doing satellite imag­ (finite impulse response) linear phase workstation has improved in perfor­ ing? filter. The detector is just absolute mance to the point where it outper­ value, then a peak detector followed by Answer (W3IWI): The AEA box has forms the old special-purpose DSP! a decay. The comparator is just a sub- it The Dalanco-Spry board had it, This whole problem can be bypassed

Apr// 1992 - Issu e #46 Packet Status Register Page 15 A Blow-By-Blow Account of the Tom Clark. W3IWI modulator frequency modulates the 1992 TAPR Annual Meeting. synthesizer. One bandpass filler in the continued...______Topic #1: 900 MHz RF path needs to be replaced to reach by writing the DSP application for the In 1985, Motorola and NEC were the Amateur 900 MHz band. general purpose workstation in the first engaged in a battle to dominate the All this cost us S20 per unit. Be place. Portable languages can be used, market for cellular telephone base sta­ jealous. so it should be easy to take advantage tion equipment. In 1990, NEC gave up o f improved workstation technology on the market, and the hardware they Outstanding issues and problems: as it comes along. had managed to sell was orphaned. In • The transmit frequency isn’t easi­ 1991, the NEC hardware at cell sites in ly moved. Luckily, this is a rela­ Block diagram of a sample applica­ Richmond was scrapped. A total of tively simple radio so modifica­ tion (not implemented): meteorology over 100 45W radios already outfitted tions are easy. satellite image reception and display. for 19.2 kbps data were made available • Frequency stability. In the cell The software can be written in surplus for $20 each. The equipment site, the radios were driven by one manageable small modules, like orbit complement for a normal cell site was com m on master oscillator at prediction or overlay generation, and 16 transmitters and 16 receivers, all 15.36 MHz. To use the radios the resulting modules can be patched nicely racked up. Six cell sites plus individually and get 1 kHz error together readily to make a complex spares were scrapped. Each cluster at 900 MHz, we need to provide application. weighs about 800 pounds and fills a an oscillator that’s good to one The SPARCstation currently used pickup truck. The salvaged radios are part in 106. Crystal manufac­ as the workstation costs about $10,000 all spoken for, but similar oppor­ turers want $80 to $90 for such after discounts. Thus the TAPR DSP tunities may become available in other an oscillator, despite the quantity project and the Radio Workstation ap­ areas. price of around $7. If anybody proach address different (but overlap­ knows a source for small quan­ The radios are set up for 19.2 kbps ping) issues. The TAPR DSP is cost tities o f 15.36 MHz oscillators, data, with a digital interface, used effective, IF you can get the software please let me know. originally for signaling for billing pur­ working quickly. Experimental ap­ • Antennas and preamps. To use all poses. They arc designed for full plications written for the Radio 100 radios, we need to get 200 duplex operation, and the receiver Workstation might serve as prototypes antennas and 100 preamps. won’t work without the transmitter for DSP-board applications. They have to be cheap and easy to operating. An analysis of the filters replicate 100 limes. The current configuration uses a indicates that data scramblers will • The vehicle locator service has DAT (digital audio tape) machine in­ probably not be required. The trans­ priority over the Amateur service terfaced via SCSI to the SPARCstation mitters arc a very simple, conservative in the 900 MHz band. The AVL or VAX, running Unix or VMS, with design. They arc serviceable, under­ (automatic vehicle locator) folks signal processing software, an interac­ standable, and robust. have been very aggressive about tive display layer like X, and Block diagram of the receiver. A defending their allocation, even FORTRAN with VMS extensions and buffer amp feeds a synthesizer-driven threatening civil suits against C for widgets. This isn’t a cheap con­ mixer, followed by a standard IF and retail stores using theft alarms in figuration, but it’s off-the-shelf. The discriminator. A measurement of the band. The North Texas code developed for this project is being received signal strength goes to a Z80 Microwave Group is also looking made available free, on the condition microprocessor. The audio and into this problem. that if you add to it, you make your demodulated data go out. The 70 MHz • Network coordination and ar­ results available free also. IF filters are from the same line as chitecture. This is mainly a politi­ Why should TAPR get involved in those used in the Microsat receiver. cal problem. It has practical im­ this project? — to help promote re­ The RF filters will need to be replaced plications, like what kind o f an­ search — to spend time doing research, with ones that can go up to the Amateur tennas are needed and where not software development — to 900 MHz frequencies. High-side in­ they have to be pointed. The big­ develop and debug applications for the jection will be needed, because low- gest problem is how to get TAPR DSP board — to help develop side injection puts the IF image in a everyone to agree on something, standards for file structures, datalink crow ded spot in the band. The anything. structures, and so forth, before it’s too modification involves removing a chip • Data pump. The standard late. capacitor and trimming a microstrip. It NET/ROM or TheNet stack of Question: How big is the publicly- remains to be seen whether the Z80 TNC’s isn’t suitable. Something available source code? processor part o f the board is useful. like the Kantronics DalaEngine, Perhaps it could be used for signal PacComm’s V53 board, or the Answer: About 100,000 lines of code, strength telemetry. Gracilis PackeTen board is comprising 300 processing primi­ needed. It has to be cheap, reli­ Block diagram of the transmitter. A tives. able, and robust enough to sur­ 15.36 MHz oscillator drives a syn­ thesizer. A power controlled amplifier vive a mountaintop environment. chain feeds the antenna. The

P a ge 16 Packet Status Register April 1992 - Issue #46 A Blow-By-Blow Account of the with controllable phase, giving many this kind o f operation as a legitimate 1992 TAPR Annual Meeting. possible antenna patterns. The satel­ use of the Internet. continued...______lite will be 3-axis stabilized using Topic #2: AO-13 orbit decay momentum wheels, so the antennas Topic #4: World’s Smallest and Phase lll-D will always be pointing straight down NOS Box? AMS AT OSCAR-13 is in a highly at the Earth. A HP-95LX palmtop computer was elliptical orbit, and its perigee height displayed running KA9Q NOS. It has This new satellite will also have an has been decreasing steadily. If this both RS-232 and Infrared data inter­ elliptical orbit. W e’ve learned an im­ trend continues, the satellite would be faces. portant lesson with AO-13: elliptical lost during 1992. However, the orbits are chaotic. It’s possible Question: What funding is needed for perigee height is starting to turn up, as (though not easy) to predict what will Phase III-D? predicted. happen with a well-known set of initial Answer: The total commitment is A graph shows the prediction conditions, but it’s not possible to com­ about $3 million. The ARRL and generated using the Cray computer pute a set of initial conditions that will AMSAT-NA have committed over running the NASA GEODYN result in a desired orbit. So, to ensure $1 million, the rest comes from that Phase III-D will have a long life in theoretical model of deep space orbits, other national groups around the the desired orbit, it will be equipped and the NORAD tracking data ob­ world. tained since the prediction was run. with a motor that can be used many The real data tracks the prediction pret­ times to make adjustments to the orbit. Question: Is that realistic? ty well. The prediction shows that The desired orbit makes exactly 3 or­ Answer: I hope so. If it isn’t, and we AO-13 will be lost in 1996. bits in exactly 2 days, so the can’t get industrial sponsorships to groundtrack repeats every other day, The effect is NOT atmospheric fill the difference, AMSAT’s with spectacular coverage. The Ger­ drag. The gravity field of the Sun and ability to develop bigger and better man AMSAT folks negotiated a the Moon are changing the shape of the satellites is at an end. The Amateur launch opportunity on the first ex­ orbit, making it more narrow and satellite program puts Amateur perimental flight of the Ariane 5 rocket moving it toward apogee. When the radio in the limelight as a technical (we can’t afford a launch like this on a eccentricity reaches 0.75, the perigee pioneer. proven vehicle). will intersect the atmosphere. The in­ Question: Is there time to get the satel­ clination is also changing. Topic #3: TCP/IP and Internet lite built? AO-13 is going to die. There’s no All sorts o f packet-related goodies Answer: Yes. But commitments have way to save it: there’s no fuel on board, are available online on the Internet on to be made soon. and there’s no way to dig a deep the com puter ucsd.edu and tom- enough tunnel through the Earth. So, cal.gsfc.nasa.gov. Soon a dedicated Question: Is there a special fund for what we need is a replacement satel­ host for AMSAT mail, amsat.org, will this? lite. be installed at UCSD in San Diego Answer: Yes, the Phase III-D under the supervision of network guru A diagram of the Phase III-D Spacecraft fund. Brian Kanlor, WB6CYT. mechanical design shows a really big Followup: What do I write on the satellite. It’s roughly triangular, 8 feet Phil Kam, KA9Q, added a hack to check? on a side, with two solar panel "wings" his TCP/IP software package to permit with a 17-foot span. The configuration IP packets to be encapsulated inside IP Answer: "AMSAT" and lots of zeroes. shown (one o f several proposed) has packets. This permits packets from You can earmark any contribution antennas for bands from 10 meters to one Amateur radio network to be sent for particular projects if you want. 10 GHz. The satellite will have to another Amateur network over the Question: Are there plans for a digital receivers on 2 meters through 3 cm, Internet, without the intervening hosts transponder? transmitters on 10 meters through 3 needing to know about the Amateur Answer: Yes, in every path. Imagine cm, and a programmable IF matrix networks. At least seven "encap" having T1 rates or better on some of capable of selecting any desired com­ gateways have been installed for this the microwave channels. bination of bands. purpose: Honolulu, Sydney, Rich­ Users in urban areas are having mond, Chicago, Las Vegas, Geneva, Question: How will the satellite know more and more trouble installing large and Ottawa. To install such a gateway which way to point? just takes someone with both radio antennas, so the satellite will have 10 Answer: The idea of using GPS smarts and a good Internet connection. dB to 20 dB more performance on each receivers to orient the satellite is Is this Amateur radio? Well, it sure is link. The 10m downlink will be still being investigated. The satel­ on the ends. capable of several hundred watts, pos­ lite will be outside the GPS orbit sibly using the long solar panel wings The Internet has proven to be a much of the time, so we need to for an antenna. The gain antennas for valuable resource. Encourage people know the antenna patterns o f the 2m and 70cm consist o f several ele­ to find a way to get on the Internet. The GPS satellites (which aren’t adver­ ments mounted on the sides o f the Internet powers that be have blessed tised). spacecraft, each with its own amplifier

April 1992 - Issu e #46 Packet Status Register Page 17 A Blow-By-Blow Account of the compensate for Doppler shift, using make a batch o f the deviation meters 1992 TAPR Annual Meeting. cither the computer interface or the available. TAPR has received mail continued...______up/down step buttons on Icom, Ken­ claiming that it’s impossible to make a Question: What data interface do the wood, or Yaesu radios. product like this for less than $100, but cellular radios have? TAPR can! A portion of the price of each kit Answer: RS-422 differential. sold is donated to the Phase III-D Question: Does the TrakBox emit any project. The documentation shipping RF at 2m? Question: What about duplexers for all now is preliminary. The assembly in­ those radios? Answer: Maybe a little, but your out­ structions are complete, but the operat­ side antennas probably w on’t hear Answer: We may just use separate an­ ing manual is a bit primitive. Since the it. tennas. We did get some duplexers Trakbox is easy to use, this isn’t too and so forth with the cell hardware. bad. The manual will be updated, and Question: Does the LCD on the Trak­ Lyle Johnson. WA7GXD. and software development continues to im­ box show the time to the next pass? Jack Davis. WA4EJR prove speed and add features. A bare board identical to the one Answer: No, it shows the present time. Hardware Projects: Trakbox, used in the R U DA K digital It does have a (slow) future predic­ Deviation Meter, Etc. transponder was passed around. tion mode via the serial port. The Trakbox is a good example of Question: How was this nice circuit a project that involved extensive inter­ board created? national cooperation. Jack Davis, A piece of unusual looking WA4EJR, was involved from the hardware mounted on a big round Answer: Chuck Green,N0ADI, did the beginning, and TAPR got involved aluminum plate was displayed, and the layout using ProCAD. TAPR uses recently. audience was asked to guess what it circuit board fab houses in Tucson was. It was a TAPR development and in Orange County, CA. The project began in Sweden with project around 1985 thatdidn’tgetalot Amateurs using building block circuit Question: How fast can a new board be of publicity. It was a data collection boards from Micromint. These boards manufactured? and experiment control system for a were based on the 8051 family of payload built by a group of high school Answer: That depends on the cost. For microcontrollers, and were originally students in Dallas. It was flown in a a standard TAPR production run of published as projects in Byte GAS (Get-Away Special) Can on the 20 to 100 multilayer boards, it costs magazine. Amateurs in Japan decided * space shuttle Discovery in 1985. Un­ about S800 to SI000 per lot. to make a special-purpose board to cut fortunately, delays before and after costs. Schematics and firmware were Mark Oppenheim. KD6KQ launch proved loo much for the bat­ exchanged between Amateurs in teries, and all the data was lost before various countries using UoSAT VITA - Volunteers in Technical it could be downloaded from the ex­ OSCAR-14. The resulting board is Assistance periment. now available as a kit from TAPR. VITA was founded 30 years ago by a group of scientists in Arlington, VA, The board is a standalone rotor con­ to serve as an information conduit to troller. This solves the problem of The prototype of the TAPR Devia­ assist developing countries with their pointing the antennas at satellites, tion Meter was passed around. A technical infrastructure. A staff o f especially fast-moving satellites in low block diagram shows a 2 meter about 75 people presendy answers re­ earth orbit, while also trying to do other receiver with a 10.7 MHz IF followed quests free o f charge. Many VITA tasks. The Kansas City Tracker has by a second IF, followed by peak volunteers are also registered with been available for a while now, but it detectors feeding an analog-to-digital their areas of expertise, including requires an IBM PC, and takes up a converter. The A/D converter is read N6ARE, WA7GXD, NK6K, slot, and requires the PC to be on by a liny microcontroller, which also HB9AQZ. In times of disaster, like the during the pass. The Trakbox runs an LED display and an RS-232 earthquake in Armenia, VITA coor­ eliminates these limitations. port, and can output the measured dinates donors, using their large com ­ deviation to either. The frequency The Trakbox is based on an 8051 munications setup at the office. HF microcontroller with RAM and pro­ synthesizer can tunc any frequency in packet and Pacsat operation are among the 2m band. A calibration oscillator gram memory, a realtime clock, and a the supported modes. is on-board in the 10.7 MHz IF to per­ LCD display. The user provides Since 1981, VITA has been work­ Keplerian elements through an RS-232 mit the board to calibrate itself. Every­ ing on using packet in developing serial port, and then controls the opera­ thing on the prototype is working, ex­ countries. Local telephone systems tion o f the Trakbox using the LCD cept a single buffer amplifier in the 135 arc often like two tin cans with a bad display and front panel controls. The MHz local oscillator. The prototype string between them, and arc unusable box interfaces directly to Kenpro was used to test the 9600 baud modem for data. Thanks to the Amateur radio rotators, and can be interfaced to other kit. work in reducing the cost of packet brands o f rotator. The Trakbox can Once the buffer amplifier problem radio, packet (on non-Amateur fre­ also control the receive frequency to is fixed, we can "turn the crank" and quencies) can be used to bypass the

P a g e 18 Packet Status Register April 1992 - Issue #46 A Blow-By-Blow Account of the Masa Sawada. JF2GPF (a good RTTY demodulator handles 1992 TAPR Annual Meeting. this). What’s worse, the bits can get continued-______TASCO smeared out in time by up to several phone network. VHF packet was used TASCO was founded by JA2AQO, milliseconds. This is what’s wrong to coordinate aid during the Ethiopian the current president, in 1979. with HF packet: 300 baud is too fast. famine. Demonstration networks have TASCO began by selling weather fac­ Most experts agree that about 100 to been operated in Somalia, Lesuthu, simile terminals and RTTY decoders. 150 baud is the limit for usual HF and Mozambique. An HF network is In the mid 1980’s, TASCO began sell­ conditions. Now and then, conditions operating in Sudan. ing Amateur packet radio equipment arc "like a wire" and there’s no prob­ into the Japanese market under license lem with multipath. Such conditions VITA first worked with packet from TAPR. They are constantly are quite rare - and that’s the only time satellites using UoSAT-2. The working on new technologies, and all HF packet works! AMTOR users can software was too manual, and the satel­ technical staffers are Amateur radio tell you that sometimes even 100 baud lite was so deaf that a large water buf­ operators. Congratulations to TAPR is too fast. falo would be needed to power the on its 10th Anniversary. uplink transmitter. UoSAT OSCAR- Clover copes with this problem by 14 was launched with partial VITA Bill Henrv. K9GWT using a signaling rate o f 31.25 baud. funding. Software delays and com­ That’s pretty slow. To get a reasonable plexity were problems. VITA hired a Clover II data rate with such a slow baud rate. programmer to develop simple-to-usc Several articles about Clover II Clover packs more than one bit in each groundstation software for their ap­ have appeared, and more arc on the pulse. Clover uses PS K with two, four, plication, and they use Quiktrak for way. The last two Proceedings of the eight, or sixteen distinct phases to en­ satellite tracking. The next step is to ARRL Computer Networking Con­ code 1 to 4 bits of information on each launch a dedicated satellite, VITAsat. ference had papers by Ray Petit, pulse. Clover then uses this scheme in There may be room for some Amateur W7GHM: 1990 about Clover I, and a time-staggered scheme with four dif­ radio payload as well. A network with 1991 about Clover II. A July 1990 ferent carrier tones, resulting in a total up to 500 groundstations is planned. QEX article featured Clover I. Several bandwidth of 500 Hz, which is a good articles have appeared in The RTTY match for available CW filters. When UoSAT OSCAR-22 was originally Journal. A series in Communications conditions arc good. Clover goes fur­ to be mainly used by VITA and Satel- Quarterly and another in QST will lead ther by adding two-level or four-level life, a group with similar purposes but up to Clover II. amplitude modulation, for even higher oriented toward medical technology. maximum data rate, without changing The power amplifier on UO-22’s non- Clover is still experimental — it the basic modulation rate of 31.25 Hz. Amateur downlink failed, so satellite isn’t a product yet. It was invented by allocations between UO-14 and UO- Ray Petit a year and a half ago. It was PSK modulation can be a problem, 22 were reshuffled. UO-22 is now an outgrowth of earlier coherent CW because its bandwidth is usually very 100% Amateur, and UO-14 is 100% experiments, which used phase wide. Clover avoids this problem by VITA and Satellife. coherent detection with very stable os­ pulsing the four tones on and off with cillators (a few parts in 108) and detec­ a very carefully-chosen pulse shape Numerous travelogue slides tion bandwidths as narrow as 0.01 Hz. called a Dolph-Chebychev function, showed people, equipment, and Such equipment can demodulate sig­ and performing the phase changes camels. nals that can’t be heard by ear. The while the pulse is completely off. The Question: Are the locals generally able early Clover articles in QEX caught result is that the energy of a four-tone to operate the equipment? Bill Henry’s attention, and they Clover signal is very tightly contained teamed up to make a product. within 500 Hz. With a 60 dB limit Answer: Sometimes. Luckily, the imposed by the quantization in the equipment has been quite reliable The particulars of Clover II are digital-to-analog converter, the Clover so far, so no maintenance has been derived to counteract what the iono­ transmitter’s sidebands are down 50 required. sphere does to corrupt a data signal. dB outside the 500 Hz. Two Clover One basic limitation of HF propagation Question: How is all this funded? signals can be spaced just 500 Hz apart is signal to noise ratio. Earlier RTTY (edge to edge) with 55 dB rejection. Answer: The equipment is purchased designs have concentrated mainly on by the "customer." Some money is this problem, by optimizing bandwidth Graphs of the spectra of Clover, HF also available through grants. and using adaptive AGC or good packet, and AMTOR show that Clover VITA does not charge for access to wideband limiters. is a lot tighter. The standard rule of the satellite. thumb says that two AMTOR signals Another difficulty with HF is the need to be 1 kHz apart, and HF packet Question: Do you have difficulties existence of multiple propagation signals need 2 kHz. The spectra clearly with importing technology? paths of different lengths. The dif­ show why: poor sideband suppression. ferential delays result in selective Answer: Sometimes. Clover is effectively much narrower. fading. On voice, this is merely annoy­ Not only that, but Clover is faster on ing, but on data it is a disaster. Out of phase signals cancel. On FSK, the real channels. Ignoring the question of 5-bit characters versus 8-bit characters mark and space tones fade separately

April 1992 - Issu e #46 Packet Status Register Page 19 A Blow-By-Blow Account of the change modes within a second if a protocol suitable for HF work. 1992 TAPR Annual Meeting. short block length is in use. The modes Anybody who writes network code continued-______range from 2.3 characters per second and wants to write drivers for Clover, for now, both HF packet and AMTOR to 94 characters per second, theoretical we can set you up with hardware and have typical real-world throughputs of throughput. The field tests have provide assistance. The command 5 to 7 characters per second. In tests shown a typical range of from 28 to 62 protocol will be defined by next week. on the air, Clover typically achieves 50 characters per second. Note thaL the Question: Isn’t frequency accuracy to 80 characters per second. receiver doesn’t just move up to higher and stability still a problem? speeds when conditions are good and Another weakness of HF packet is down to lower speeds when conditions Answer: With the faster CPU, the DSP the error control scheme used. With are bad. It can figure out by listening no longer has to do Reed-Solomon packet, a long frame of up to 30 decoding. That means it has seconds is sent, and every single bit in to the signal what exactly is wrong with the signal and request the mode enough spare horsepower to do the frame must be received correctly, that best fils current conditions. For more frequency acquisition and or it is discarded. Because o f this instance, if it notes that phase disper­ tracking. Clover can now handle limitation, HF packet operators must sion is bad, it can fall back to a mode frequency errors o f up to 40 Hz, run small packet sizes of 32 or 64 char­ with fewer phases. If it notes that it has which is similar to the guidelines acters. This makes the packets short excess signal to noise ratio, it can com ­ for HF packet. enough to get through (sometimes), mand the other station to reduce but increases the cost of packet headers Question: What about intermodulation power. (This can lead to the rather and waiting between packets. That’s distortion in the transmitter? disconcerting situation where the how a 300 baud mode gets down to 5 transmitter’s meters are not moving, Answer: Measurements of high-end rigs or 7 characters per second. Clover and the receiver’s audio has no audible show very good IMD. A worse prob­ uses a forward error correction techni­ tones, yet characters are still moving lem is broadband noise, which is about que called Reed-Solomon coding. through the link!) 40 dB down. That doesn’t seem to This technique transmits a few extra hurt, either. bits, and uses the carefully encoded The implementation is DSP, DSP, redundancy in the data to correct the DSP. The input jack goes to a trans­ Question: What’s the price? received data without requiring a former and a 16-bit A/D converter, and Answer The introductory price will be retransmission. For example, a Reed- the rest is digital. The A/D converter S995. This is a lower price than an­ Solomon code that is 60% efficient can is a 16-bil sigma-delta oversampling nounced before, because it’s now a PC correct 25 errors in a block of 255 bits. converter like the ones used in digital plugin board rather than a box. The Because the Reed-Solomon code can audio applications. It doesn’t need any parts arc expensive, even the socket for correct some errors in each frame, anti-aliasing filter, and it has lots of the DSP chip is expensive. The board Clover is able to send longer frames dynamic range. It currently costs $20, is 4 layer. without losing too many to errors. Of but should get cheaper. The transmit course, sometimes long frames just audio is also a 16 bit oversampling Question: What is the peak to average don’t get through due to fading condi­ audio component, followed by a power ratio? tions; in this case Clover can fall back simple filler to get rid o f the residual Answer: 3 dB for all modes. to shorter frame lengths. 100th harmonic. A Motorola 56001 DSP processor supplies the signal Question: Is it legal? As W3IWI has pointed out, HF calls processing horsepower. The original Answer: Yes. It’s not multiplex because for adaptive modems. Clover is about design used a 6809 microprocessor for as adaptive as you could want. There the four tones are sent serially rather general control functions, but it ran out are 8 basic modulation modes to than in parallel. The emission desig­ of gas. The current prototype now uses choose from (different numbers of nator is 500HJ2DEN. The Chief En­ a 68EC000 processor at about 30% phases and amplitudes for each pulse), gineer and Chief of Enforcement of the utilization. The board contains only times 4 frame lengths, plus 4 different FCC have both agreed verbally that bootstrap ROMs; the Clover code is Reed-Solomon codes of varying ef­ this modulation is legal. downloaded from the PC. ficiency and error-correction Gwyn Reedy. W1 BEL capability, for a total of 128 different Vic Poor is writing a Clover driver modulations. Every one o f those 128 for Aplink. The Clover board has PacComm Topics modulations has the same 500 Hz FIFOs on the input and output to relax PacComm is currently working on spectrum. The Clover modem also realtime requirements, which is ex­ a custom packet protocol for commer­ controls the transmitter output power. pected to be especially helpful for PCs cial HF applications. It runs long Obviously, mode and power selection running Windows. frames, but avoids the problems of has to be automatic! Two working prototype Clover AX.25. It uses a "superframe" con­ The receiver measures the phase, boards will be displayed at Dayton. On taining multiple copies o f the address time, and frequency dispersion o f the initial release, the card will do only and multiple checksums. It uses a received signal and picks a mode. It Clover. If anybody wants to write selective NACK protocol so receiving sends an order to the transmitter other modems for the board, the door stations need only NACK missing specifying which mode it wants. It can is open. A more pressing need is a new pieces of each superframe.

P a g e 20 Packet Status Register April 1992 - Issue #46 A Blow-By-Blow Account of the needs to add 9600 baud. It is versatile: Fred Treasure. KE5CI 1992 TAPR Annual Meeting. the user can switch to internal or exter­ continued...______nal clocks, route the push-to-talk, and A Packet-Controlled Telescope Topic #1: PACTOR choose the TNC’s built-in 1200 baud In 1987, Bill Neely, KC5ZG, pur­ PacComm is exclusive licensee of modem or either of two external chased a large telescope minor, with PACTOR in the USA (for a few years), modems. An LED indicates when you plans to automate the pointing arrange­ and point o f contact for PACTOR. have the settings wrong — this tends ments. Since then, the system has grown PACTOR is an ARQ protocol more like to cut down on user support calls. a little... AMTOR than like packet The PAC­ An integrated packet radio system Block diagram of the observatory TOR controller will also do RTTY and containing the modem, the TNC, and the system. A control computer in town AMTOR, and automatically falls back RF circuitry all in a single box is in communicates via a 9600 baud packet when talking to a non-PACTOR station. prototyping now. The original plan was link, through a dedicated repeater site, It stores partially-received frames in to mount the radio on the circuit board, through another 9600 baud packet link memory and tries to combine them to get but interference prevented that from to the communication and storage com­ one good frame. This technique is called working. So the radio is now mounted puter in the "warm room" at the obser­ "memory ARQ." The box is binary in the chassis, with the side benefit that vatory ranch. That computer talks via a compatible with the original German there is now room for two separate 2.5 Mbps ARCnct link to the control version. Hardware is expensive to build radios. computer, which in turn talks via 1200 in Germany, so PacComm is building baud asynchronous RS-232 to the com­ PACTOR controllers in the USA. An Topic #4: TNC Upgrades puter that controls the pointing. Whew! Aplink driver is on the way. When running 9600 baud con­ The NF/Observatory tracks asteroids Topic #2: Baycom tinuously (like on a satellite downlink), and other objects of interest, capturing the TNC needs to support a terminal Baycom (pronounced Bye-Comm) is images using a CCD camera on the 17.5 baud rate greater than 9600. TheTINY- a packet program for the IBM PC like inch telescope. Congress has generated 2 can run 19200 baud continuous, and DIGICOM64 for the Commodore 64, an initiative to shoot down asteroids it’s the only TNC that can do that out of from the same German team. They have rather than let them collide with Earth. the box. TINY-2’s are now shipping now formed a company, and have This observatory has volunteered to with 10 MHz Z80 microprocessors, licensed PacComm (non-exclusively) to gather data on near-earth orbit asteroids which enables them to run at 38400 baud distribute in the USA (and to work to in support of this project. on the terminal port. enforce their copyright in the USA). The name "NF/" stands for "Neely A high speed data controller based on Two modems are to be available: a serial Fraska Bar," the name of the ranch on the V53 processor with an 85230 serial port modem based on the TCM3105, which the observatory is located. The chip and a fancy power supply on-board powered from the port and physically ranch is about 25 miles from Silver City, is being marketed mainly to commercial inside the port connector, and a version NM, at an elevation of 5800 feet. The customers — it’s too expensive for the based on the AM7911 in a box with HF packet repeater is on Baldcc Peak. capability. The PC-100 series will also ham market. A PacComm HandiPackct be upgraded for 4-port Baycom com­ is in use on the Russian space station The 9600 baud links run on Mocom patibility, 300/1200/9600 baud, with MIR, which has generated lots of 70 radios with Texnet 9600 baud modem disconnect and mounts for Tekk publicity. They are also used in the modem. The Texnet network control radios. These products may be available ground terminals used with the DARPA processor (NCP) has been modified to by Dayton. Microsat project (not to be confused with run KISS with 2048-byte packets for AMSAT’s more sophisticated TCP/IP. The Silver City to Baldec link Topic #3: NB-96 Product Line Microsats). is on 442.5 MHz, line of sight, with 4-element yagis on each end of the link. The NB-96 line is a licensed version A 1200 baud modem about the size The link from Baldec to the ranch is on of the G3RUH 9600 baud modem. The of your thumb is shipping 100 to 200 447.5 MHz. There’s no line of sight path weaknesses of the original design for full units a month to commercial customers, on this link, so there’s a 16-element yagi duplex use have been fixed. The board who are now asking for a tiny 9600 baud on the tower on the mountain and an 11 has more groundplane and more bypass modem. capacitors. Receive and transmit circuits foot dish with 21 or 22 dB gain at the have been separated. The components ranch. that determine the modem speed are now Pete Eaton made a few an­ The system can transfer a 512x512 on a header, so you can pick whatever nouncements, then the meeting broke for pixel image with 4 bits per pixel (about baud rate your radios can support the day. It reconvened at 9:00 AM on a half megabyte of data) in about 10 The EM-NB96 external version of Sunday. minutes. More typically, it transfers a the NB-96 has been out of production, 320x200x8 VGA image in about 1 but now it’s back in production. It is minute. This kind of image is suitable intended as a stopgap until DSP modems for previewing the results. The full become available and affordable, or for results are stored at the site, and the operator who already has most of the transported using magnetic tape. modems he expects to need and just

April 1992 - Issue #46 Packet Status Register Page 21 A Blow-By-Blow Account of the Answer: The data is recorded in a stand­ TAPR 9600 baud modem) to remove 1992 TAPR Annual Meeting. ard format. However, there is only clock jitter and clock rate errors, the continued...______one other telescope that’s as com­ transmitted signal can be perfect. The system includes three 80286- pletely radio-controlled as this one: Most TNCs arc crystal controlled, so based computers and one XT-class the Hubble Space Telescope! The not much buffer is needed. machine. A request for a scries of im­ team gets invited to professional The bit regen repeater has some social ages is entered into the computer in Sil­ astronomy events. The professionals impact as well: the repeater operators get ver City. It goes through the links to the couldn’t do a project like this for some control over the type of traffic that ranch house, which turns on the tele­ S100,000. is transmitted on the channel. A station scope and the rest of the computers. Lots Question: Is compression used on the that habitually hogs the channel can be of computers made more sense for this links? throttled by the node TNC by simply job than a larger multitasking machine, generating a glitch in the middle of each because realtime control was needed. Answer: We tried LZW compression, packet they transmit. Technical com­ and it gave only about 25% compres­ The XT tracking computer can auto­ pliance can also be ensured. sion on this type of data. T h a t’s not matically calibrate the positioners, start­ worth the extra trouble, since there is Question: What are the pros and cons of ing from the weatherproof "parked" plenty of capacity on the links. checking the CRC before regenerat­ position. Fixed sensors on the telescope • ing the bits? mount can get it pointed close enough to Question: What polarization are the find a calibration star. Then the tele­ links using? My experience is that Answer: If the TNC waits for the entire scope automatically locks onto the bright vertical d o e sn ’t work in the moun­ frame to arrive so the CRC can be object near the center o f the field. tains. checked before transmitting, it ends up acting just like a digipeater. That Telemetry about the weather and control Answer: We chose horizontal, more or cuts the throughput by a factor of at voltages go back over the link to the less by guess. It works. in-town computer. least two. The "lid filter" function Question: What weather sensors arc in­ mentioned above d o e s n ’t require The second computer provides the stalled? checking the CRC: if the node TNC timing signals to the CCD sensor and glitches the wrong frame because of stores the resulting image on its hard Answer: Anemometer, a cloud sensor that works by sensing the temperature bit errors in the received Same, the disk. Best performance from the CCD is frame w ou ld n ’t have been accepted of the sky versus the ground, a mois­ obtained by tuning the precise voltages at the receiving end anyway. The applied to it. This telescope achieves ture-detection grid, and thermistors to other aspect is the need for the output about 25 electrons o f noise. Compare measure temperature. to come on the air quickly as soon as this to the best NASA sensors at 3 Question: What kind of cooling is used? a signal is detected on the input. This electrons of noise; pretty good for an is required so other users w o n ’t start amateur effort. About 60 images are transmitting and colliding with the stored on the hard disk drive, then they Answer: A three-state thermoelectric first input. With the FIFO, the are dumped in a batch to a magnetic tape cooler and liquid cooling. repeater only sends a few bits of gar­ drive attached to the computer in the Question: Tracking rates? bage data as a busy tone before the ranch house. About once a week, the real bits start to come out. data is fetched by car. Once the tape is Answer: Completely variable. verified, the hard disk is erased. The Lyle Johnson. WA7GXD Question: Are the bit regen kits available telescope dome automatically closes, the now? telescope parks, and powers off. The Bit Regenerative Full-Duplex Answer: Yes. I t ’s just a couple of parts. entire process is completely automated; Repeaters The bit regenerator could be used on no human intervention is required. The Why full duplex? It helps to cure the a 1200 baud regenerative repeater, telescope system has failsafe interlocks: problems caused by hidden terminals. too. if moisture is detected, or if the link fails, The coverage area can be controlled the system automatically parks and shuts using antenna patterns, or to a lesser With a central repeater, the users can down. extent by varying the repeater transmit use directional antennas and get better power. The Tucson LAN has a large performance. The single-point The system cost about $5000, plus • reliability is about the same as a single about 5000 man-hours, mostly spent on radius of 150 miles, and the full duplex repeater helps throughput. It helps sta­ central digipeater. The digipeater at a the programming. Bill Neely, KC6ZG, good site probably needs cavities and Lori Neely did most of the program­ tions at the edges of the LAN to com­ municate. anyway, so the additional cost of going ming; Fred Treasure and Barbara full duplex is minimal. Treasure, N5HJN, provided most of the With bit regeneration, the repeater Mike Curtis. WD6EHR hardware. K2GNR and the Jet Propul­ demodulates incoming signals and sion Laboratory provided the camera remodulates them before retransmis­ Experiences with 9600 Baud chips. NASA provided the magnetic sion. This allows the repeater to control tape recorder. the deviation of the transmitted signal. Working with many other con­ By using a bit regenerator with some tributors, Mike has created a Question: Arc there other sites sharing beginner’s handbook for 9600 baud the data format? FIFO buffering (like the one on the new

P a ge 22 Packet Status Register April 1992 - Issue #46 A Blow-By-Blow Account of the (Sorry. I didn’t catch this ad-hoc Answer No. 1992 TAPR Annual Meeting. speaker’s name or call.l continued-______Question: Did you make any modifica­ tions to the K9NG modem at all? operation. 9600 isn ’t as hard as people Experience with Mitrek Radios at think it is. The only big problem is get­ 9600 Answer Some have done some work on ting hooked up to the radio. On transmit, We obtained some surplus Mitreks. the filters and DCD. the radio needs fairly linear response A technician from Motorola d id n ’t think Question: Did you notice any perfor­ from 100 Hz to 5 kHz, low phase distor­ th ey ’d work on 9600. They do, with mance loss when the front end filter tion, and a true FM modulator. On both the G3RUH modem and the K9NG was removed from the Mitrek? receive, it needs good linearity. modem. We intended to support an ap­ plication for appliance operators, so we Answer: No. We have three sites that are There are a few radios capable of wrote a paper that describes the neces­ heavily infested with other transmit­ doing 9600 baud out of the box. The sary modifications in detail. The Mitrek ters, and haven’t had any real Tekk KS900L, the D4-10, and the Ram­ is fairly easy to modify. Several people problems. sey kits are all good. The Kantronics have successfully followed the paper. DV R2-2 works but is n ’t recommended Question: How many hops work in the where other strong signals are a problem. IAn article by Mark Schroeder, network? WB7QGN and Joe Oliver, WB7BNI Multimode radios arc generally good Answer: 3, 4, 5. The link to Chicago describing how to interface the MITREK prospects for conversion, because they works, even though it ’s n o t 9600 all radio to the K9NG modem appeared in use a separate circuit for FM. the way. the April 1990 issue ofPSR.) Question: What about removing extra Question: How much difference did the Filtering from the discriminator? I t ’s important to use shielded wire custom EPROM in the G3RUH like RG-174. The original instructions Answer: Whatever works. modem make? called for running the wires through a Question: What test bench setup do you hole in the case, but we found it possible Answer: We d id n ’t make one. The use for bit error rate measurements? to run the wires through the existing I/O default modem is good enough. connector, which makes the modified Answer: The G3RUH modem has a bit Question: Do the Mitreks also have a low radio much more serviceable. About 10 error detector, which generates a IF? are in use, with paths ranging from a few click for each error. Just hook up an miles to 40 miles, vertical and horizontal Answer: No. audio amplifier and tune for mini­ antennas. When two of the radios are mum clicking. stacked on top of each other, some IF Eric Gustafson. N7CL Question: What parameters do you crosstalk causes interference between recommend for 9600 baud links? the two radios. More Experiences with 9600 Answer: TXDELAY as low as 3 usually It’s important to get 15 to 20 dB Baud works, but 6 to 10 is better. TXTAIL margin on the links. We did biterror rate The local oscillator in the Mitrek about 2. FRACK (the T1 timer) at 4 tests, even though that isn ’t necessarily generates about 1.5 watts of power, or 5. These parameters should be the best indicator. We use Comet and which is applied to the mixer. If you slightly more aggressive than at 1200 Diamond dualband antennas for back- follow the Motorola instructions for baud. to-back VHF/UHF nodes. Horizontal tuning the front end filters, you get a Question: Can 9600 be used co-channel polarization with beam antennas seems strong LO signal everywhere, especially with 1200? to work better. on the fccdlines. This signal will leak The biggest problem with the Mitrek into any other Mitrek, in both directions. Answer: Yes. In fact, we have a repeater We had this problem in a commercial that is dual mode 9600/1200. It is bandwidth. We replace the 4-polc filter in the front end with a wire, which installation in a mine in Nevada, result­ seems to work, though there is n ’t ing in crosstalk between vehicles when much 9600 activity. is a little touchy at 10.7 MHz. We have avoided preamps because of problems they were close together. We were able Question: Is 9600 used on 2m in Los with turnaround time. W e run to realign the front end filters, and the Angeles? TXDELAY of 3 to 5. W e’ve tried extra attenuation helps substantially. Answer: Yes, on 2m and on 70cm. TCP/IP, but we usually run NET/ROM. We use Tekk radios for 1200 bps We have a Gracilis packet switch, but it ’s telemetry. Their front ends c a n ’t take Question: What about the Motorola not fully installed and working. other strong signals. We have found Mostar 800 MHz radio? Q uestion: Can you really run them reasonably useable; others have Answer: Never heard of it. TXDELAY at 3 to 5 with K9NG had more luck. Question: Thanks for writing the modems? Out of 10 radios, one was 15 kHz b e g in n e r’s notes! Answer: Yes, even with the M itrek ’s off frequency — with 15 kHz bandwidth filters! Filters were Answer: It was fun, and I had lots of help. antenna relay. misaligned, resulting in over 20 dB of I hope 9600 baud will take over as Question: Did you modify the DCD cir­ people try it and find it so much belter loss. The Tekk radios perform very cuit in the K9NG modem? poorly under thermal cycling. The that they want to abandon 1200 baud.

April 1992 - Issu e #46 Packet Status Register Page 23 A Blow-By-Blow Account of the primary response (on 8 out of 8 Answer Not with Repco. With Ramsey, 1992 TAPR Annual Meeting. units). my only experience is with their test continued...______Question: Maxars? equipment, which was junk. transmitters perform pretty well, WA7GXD: Built a Ramsey kit. The probably because they have to pass Answer: Not tried. We have used Max- Ramsey people were cooperative FCC tests, but the receivers d o n ’t. We tors successfully. about filling shortages in the received went to crystal manufacturer Hy-Q, Question: Kantronics D4-10? kit. Got it working for about an hour, sort of a Filters-R-Us house. They and then it died. H aven’t had a chance provided filters and crystals that cured Answer: Not tried. The Kantronics 2m to work on it since. the problems with the Tekk filters and version is just wretched. crystals, including frequency jumps Question: What is the part number of the KE3Z: HasaRamsey radio workinginthe and frequency errors. So now we order filter you use in the Tekk radio? ARRLLab. The coil in the transmitter the Tekk radios without quartz, and get was way off, but could be tweaked. a cheaper price. Answer: Custom part number Hy-Q The spectral purity d id n ’t meet the QMF21MB30 roofing filler. This FCC requirements; it w asn ’t even For many other radios, we found the mod requires other component chan­ close. Ramsey has said there is a new filters weren’t really quite wide ges too. The 450 filter is SFG or SFH model coming out, and not to bother enough for 9600. For a given radio, line. The SFH450F works at 19200 or publishing a review of the current you can find an optimum FSK shift but 9600 without compensation. model. A user could provide postfil­ low signal-to-noise ratios. Often, you Question: What bandwidth? tering to meet the rules. The receive have a choice between high error rate side w asn’t great either. with the best S/N performance or low Answer: +/-12 kHz, which is a bit wide error rates but poor S/N performance. for 9600, but that allows for some N7CL: I prefer receivers that have a frequency error. double-balanced mixer in the front Murata-Erie is now making 450 end. kHz ceramic filters specifically Question: So you would need a channel designed for data transmission, in the wider than 25 kHz? Somebody: I just built a new 220 MHz standard package. Two bandwidths. Ramsey kit, and it ’s hot. I have it are available, about right for 9600 and Answer: It w ou ldn ’t interfere with, but transmitting on 9600, still working on 19200 baud respectively. So now the might get some interference from, ad­ receive. jacent channels at 25 kHz. With the G 1st IF in many radios can be opened up WA7GXD: Most radios work fine on by just replacing the filter with the filter, you get +/- 9 kHz, which is about right for 9600. The skirts are a bit high, frequency — the question is how right bandwidth unit The resulting well they work where they a ren ’t eye patterns look just like the trans­ but that’s how they get flat group delay for data. supposed to work. mitted signal. Question: What about the Alinco data Question: W hat’s a Tekk radio? Question: W hat’s a source for Murata filters in small quantities? radio? Answer. A very small crystal-controlled Answer: Maybe TAPR should provide W1BEL: Itdoesn’tpass dircctFM sig­ transceiver that’s both cheap and inex­ nal without modification. pensive. They are available for this service. Amateur frequencies as well as the Question: If we use a 455 kHz model W3IWI: I ’ve heard that the only dif­ commercial units we use. The trans­ instead of a 450 kHz model, it would ference is the front panel and the mitter tuning is very broad. Unfor­ work in other radios than the Tekk. fact that it d o e s n ’t come with a tunately, so is the receiver tuning. microphone. Answer: So would the 450 kHz model, Question: What application did Tekk but it would be more painful. Somebody: The manual on my Alinco originally intend for these radios? is the worst I ’ve seen. Question: Was the 2nd LO frequency Answer: Not sure. They are advertised changed because of stability N7CL: The manual always comes last. for telemetry applications. problems?

Question: There is aradioby Maxim (sp?) Answer: The stock crystals were just on Pete Eaton said thanks to everybody that’s similar to the Tekk. And the the wrong frequency. who came. If y o u ’re going to be at W A 40N G commercial product uses a Question: How much power does the Dayton, stop by the booth and say hi. Motorola Radius board set Do you Tekk radio generate? have any experience with these? He then closed the TAPR annual Answer: Just under 2 watts. meeting at 10:40 AM . Answer: We tried the Radius, and it worked well except for the Motorola Question: What quantity do you order to local oscillator problem. It uses a get prices of $40 to $50 each? MMIC mixer with no RF stage, with Answer: 8’s. the result that every harmonic of the LO out to at least 2 GHz is coming out. Question: Any experience with Repco or strong. They also have a spurious Ramsey radios? response 900 kHz away from the

P a ge 24 Packet Status Register April 1992 - Issue #46 Software Library Update 3. C-BBS - Packet BBS program writ­ 14. TNC-2 Software notes - Notes on ten in C language. Originally written by TNC-2 versions 1.1.0 through 1.1.7 by Hank Oredson, WRLI, current version by Howie Stein, N2WX. byLouNigro, KW7H K3RLI and AG3F. 15. WA7MBLBBS - PacketBBS sys­ 4. EZPAC11 - A menu-driven NTS tem by Jeff Jacobsen, WA7MBL. message formatter by Mike Intel. Disk also 16. WRLI BBS - Packet BBS system In addition to supplying various kits contains a copy of WA7MBL’s YAPP ter­ by Hank Oredson, WRLI. and firmware, TAPR maintains a minal program. 17. YAPP-A packet terminal program library o f packet radio-related com ­ 5. MONAX - A program for monitor­ by Jeff Jacobsen, WA7MBL. Supports puter software. Disks arc currently ing a packet radio channel and gathering split-screen operation, ASCII and binary available in 5-1/4 in. MS-DOS format system statistics. Described in a paper (in­ file transfer. for S2.00 each, and in 3-1/2 in. for cluded on the disk) presented in the 6th 18/18a INTRO TO TCP/IP - Much ARRL Computer Networking Conference descriptive and reference information on $3.00 each, including mailing (slightly by Harold Price, NK6K and Skip Hansen, TCP/IP. more for foreign orders). In the future, WB6YMH. 19. LAN-LINK - Packet terminal pro­ possibly formats for other computers 6. Ham Comm - A DSP RTTY program gram by Joe Kasser, G3ZCZ. Also sup­ will be added. The current library list­ with VGA spectrum display, O ’scope, ports the non-packet modes of PK-232, ing contains the following entries (of tuning indicator, all real time. Uses simple KAM andMFJ-1278. which some are two-disk packages in 1 chip interface, schematic included, all 20. ARES/Data - A packet radio data the 5-1/4 in. versions only; single disks parts available at Radio Shack. Powered base system for emergencies by Weo in 3-1/2 in.). Additions to the software by serial port. Moemer, WN6I and Dave Palmer, N6KL. 21/21a MSYS - A multiconncct BBS library are always welcome, however 7. PBBS lists - Master PBBS list com­ piled by W9ZRX. with telephone modem, terminal, node and we do request that they be submitted 8. R95 - A conversion utility to permit TCP/IP support by Mike Pechura, either by, or with the expressed permis­ transmission of binary files by packet radio WA8BXN. Requires KISS mode. sion of, the author. TAPR attempts to by Greg Jones, WD5IVD. 22. G8BPQ NODE - A NET/ROM- provide the latest versions of all 9/9a ROSERVER/PRMBS - A packet compatiblc multiconnect software packet software; updates are appreciated. radio BBS with telephone modem support switch by John Wiseman, G8BPQ, which TAPR reserves the right to screen any by Brian Riley, KA2BQE. can be run standalone or in conjunction submissions and restrict the library 10 ROSE - The ROSE switch by Tom with a BBS package, ARES/Data or DX content as necessary. Both freeware Moulton, W2VY. Cluster software. 23. Compression/archiving utilities - and shareware are acceptable. 11/1 la KA9Q NET - Executables and source code for the NET version of TCP/IP Utilities for archiving and un- archiving The following is a brief description by Phil Kam, KA9Q, with enhancements .ARC, .ZIP, .ZOO and .LHZ Files. o f the current listings in the TAPR by Joe Buswcll, K5JB. 24. THS - A terminal program for software library: 12. WXN Weather Server - A multi­ TNCs with WA8DED firmware or the 1. APLLNK - A concurrent -AMTOR user weather server that runs as an applica­ DRSI PC*PA by Peter Heinrich, MBO and packetBBS system by Victor D. tion on the G8BPQ switch. Uses the Heath HB9CVV. Poor, W5SMM. ID-4001 Advanced Weather Computer for 25. NTS traffic generator - A software 2/2a BB - A multiconnect packet mail­ weather data. Includes PC user program package for generating NTS traffic by Bill box program by Roy Engchausen, AA4RE. that runs on a TNC2. Bowman, VE4UB. Requires the use of AEAorWA8DED host 13. TNC-1 source code - Sources for 26. NM1D DOSgate - A program al­ mode or G8BPQ switch software for opera­ the TAPR TNC-1 firmware. lowing remote operation of a PC via packet tion. radio by Rich Bono, NM1D.

TAPR Badges! TAPR now offers name badges. These are 3.5 by 2.5 inches, with the TAPR logo and name in blue, plus your name and callsign engraved in black. I t ’s jus t what you’ve always needed to wear to ham fests and s wapmeets. The price is $ 10 (including shipping in theU.S.). Your badge will be engraved exactly as shown below:

CALL:

NAME:

April 1992 - issu e #46 Packet Status Register P a g e 25 Software Library Update, continued...

27. SV7AIZ BBS - a multiuser, multi- Current versions in TAPR software library - As of 14 April 1992. Items with ** port BBS by Spiros Kavalaris, SV7AIZ for notation have been updated since last listing. WA8DED/AEA host, DRSI or KISS TNC Disk No. Name Version Date running G8BPQ switch. 1. APLINK VER. 6.04 02-24-92” 28. TEXNET Applications - Software 2. AA4RE BBS VER. 2.12 03-06-91 for use with the TEXNET switch by Texas 3. CBBS VER. 6.6 03-09-90 Packet Radio Society. 4. EZPAC VER. 1.1 01-09-89 29. INTRO TO PACKET RADIO - A 5. MONAX 10-30-87 tutorial on Packet Radio by Larry Kenney, 6. Ham Comm VER. 3.08 03-08-91” WB9LOZ. 7. W9ZRX BBS LIST 04-24-89 30. MICROSAT Ground Station 8. R95 09-01-89 Software - Programs and information for 9. ROSERVER PRMBS VER. 1.58 07-31-91” use with the MicroSals (AO-15, DO-17, 10. ROSE SWITCH VER. 911130 11-30-91” WO-18 and LO-19) as well as UO-14 by 11/11A KA9Q NET VER. K5JB.K10 03-18-92" Harold Price, NK6K and Jeff Ward, 12. WXN Weather Svr. Ver.3.18 02-08-92" G/K8KA. 13. TNC1 CODE 05-30-84 31/31a KA9Q NOS - Executable for 14. TNC2 NOTES 03-28-90 KA9Q’s NOS version of TCP/IP, with en­ 15. WA7MBL BBS VER. 5.14 02-11-90 hancements by Kelvin Hill, G1EMM. 16. WORLIBBS VER. 13.09 03-01-92” 32. PAMS - A Personal AMTOR Mail­ 17. YAPP VER. 2.0 12-18-86 box System by Victor D. Poor, W5SMM. 18/18A INTRO TO TCP/IP 09-09-87 33. TNC-2 Monitor - A Z-80 monitor 19. LAN-LINK VER. 1.59 03-27-91 for the TNC-2 and clones by Paul Newland, 20. ARESDATA VER. 1.5 01-20-91 AD7I. 21/21A MSYS VER. 1.13 02-11-92” 34. GIL - Graphics Interchange Lan­ 22. G8BPQ NODE VER. 4.04 07-31-91 guage - Permits a convenient way to 23. UTILITIES tramsmil more than just ASCII text mes­ PKARC VER. 3.6 06-01-88 sages, such as animated graphics drawings PKZIP VER. 1.10EX 03-15-90 or diagrams over digital radio links. LHA VER. 2.13 07-20-91 35. PACKET - A TNC-2 program with ZOO VER. 2.01 08-25-88 features such as windowed operation and 24. THS VER. 2.50 11-11-89 multi-connects. 25. VE4UB NTS VER. 091891 09-18-91” 36. F6FBB BBS - Supports 15 lan­ 26. NM1D DOSGATE VER. 1.14 11-29-89 guages, YAPP support, multiconnects, 27. SV7AIZ BBS VER. 3.24 04-05-90 compressed message forwards 28. TEXNET VER. 1.6 02-05-91 29. INTRO TO PACKET RADIO 11-04-90 Orders for any o f the above disks, 30. MICROSAT GROUND-STATION SOFTWARE new submissions or updates to the PB 05-0991 TAPR software library should be sent PG 02-12-91 to the TAPR office. PFHADD 12-21-90 PHS 12-21-90 31/31A KA9QNOS VER.G1EMM 1.6 01-19-91 32. PAMS-Personal AMTOR Maifoox Ver. 2.03 03-15-92” 33. TNC-2Z-80 Monitor Ver. 2.00 09-02-91 34. GIL Ver. 1.03 03-30-91” 35/35A. PACKET Ver. 5.0 02-29-92” 36/36A/36B. F6FBB BBS Ver. 5.14 03-31-92”

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P age 26 Packet Status Register April 1992 - Issue #46 TUCSON AMATEUR PACKET RADIO P.O. BOX 12925 TUCSON, AZ 85732 602-749-9479 (VOICE) 602-749-5636 (FAX)

ORDER FORM - Kits - Firmware - Software All prices subject to change without notice and are payable in U.S. funds Prices include shipping and handling except foreign air Please allow six to eight weeks for your order to be shipped

K ITS a n d FIRMWARE Qty Item Unit Price Total ____ PSK Modem $115.00 ...... ____ Cabinet for PSK Modem 10.00 ...... ___ K9NG 9600 Baud Modem + ...... new____ TAPR 9600 Baud Modem 70.00 ...... new____ Bit regenerator 10.00 ...... new____ Clock option 5.00 ...... XR2211 DCD Mod. 15.00 ...... ____ State Machine DCD Mod. 15.00 ...... ____ State Mach. DCD w/lnt. Clock 20.00 For KPC2 or any other TNC w/o 16X or 32X internal clo ck...... ____ PK232 Modem Disconnect 20.00 ...... ____ METCON-1 Telemetry/Control 75.00 ...... ____ Voltage-to-Frequency module 25.00 ...... ____ Temperature-to-Freq. module 35.00 ...... ____ TNC-2 bare PC board 30.00 (includes schematic plus disk with assembly/operating manuals and EPROM code) ...... new____ TrakBox 185.00 ...... ____ 32K RAM W/TNC2 update docs 12.00 ...... ____ TNC-2 1.1.8 w/KISS EPROM 12.00 (includes 1.1.8 Commands booklet) ...... ____ TNC-2 WA8DED EPROM 10.00 (8 connect version for ARES/Data standard - 4, 12, 16 available)...... TNC-1 WA8DED EPROM 10.00 ...... ____ PK-87 WA8DED EPROM 10.00 ...... TNC-1 KISS EPROM 10.00 ...... ____ TNC-2 KISS EPROM 10.00 ...... ____ 1.1.8 Commands booklet 5.00 (The full TNC-2 command set for 1.1.8) ...... ____ PSR sets, Issue #1 to present 30.00 ...... _____ TAPR Badge 10.00 (include separate order sheet) ...... ____ TAPR Packet Radio videotape 15.00 ......

S O F T W A R E - Please circle disk numbers requested. 1 6 11/A* 16 21/A* 26 31/A* 36/AB' 2/A* 7 12 17 22 27 32 3 8 13 18/A* 23 28 33 4 9/A* 14 19 24 29 34 5 10 15 20 25 30 35/A*

* Indicates two-disk package (one disk in 3-1/2 in. format). ** Indicates three-disk package (two disks in 3-1/2 in. format). We attempt to provide the latest versions of all software.

Total disks circled - 5-1/4 in. MS-DOS format (2. 9. 11. 18, 21, 31 & 35 are 2 disks ea., 36 is 3 disks) x $2.00 = ______

Total disks circled - 3-1/2 in. MS-DOS format (36 is 2 disks) x $3.00 = ______

Credit Card Number______Expires______(VISA/Mastercard only) Subtotal

Signature ______Arizona Residents add 5% tax For AIRMAIL orders to be shipped outside the United States, please contact TAPR for shipping charges.

TAPR is a non-profit, volunteer operated amateur radio organization. Membership in TAPR, including a Membership subscription to Packet Status Register, the quarterly TAPR newsletter, is $15 per year in the US and possessions, $18 in Canada and Mexico and $25 elsewhere. Membership and PSR subscription cannot be separated. $12 of the dues is allocated to Packet Status Register. To order TAPR badges, please enclose separate order forms (or Airmail outside U.S. copies) as provided in Packet Status Register or available from the TAPR office.

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Address

City & ZIP State ______Code

04/92a The Tucson Amateur Packet Radio Corporation is a non-profit, TAPR Board of Directors scientific research and development corporation. TAPR is Board Mcmhcr Term CompuServe chartered in the State of Arizona for the purpose of designing and Clark, Tom W3IWI, 1993 71260,3640 developing new systems for packet radio communication in the Crawford, Jerry K7UPJ, 1994 70521,2356 Amateur Radio Service, and for freely disseminating information Davis, Jack WA4EJR 1994 72356,441 required during, and obtained from, such research. Eaton, Pete WB9FLW, 1993 72727,2641 The officers of the Tucson Amateur Packet Radio Corp. are: Jones, Greg WD5IVD, 1994 72047,3455 Morrison, Dan KV7B, 1994 70541,2374 Nielsen, Bob W6SWE, * 1994 71540,2364 Bob Nielsen, W6SWE President Price, Harold NK6K, 1993 71635,1174 Dave Toth, VE3GYQ Vice President Toth, Dave VE3GYQ, * 1993 72255,152 Mike Lee, WB6RTH Secretary/Treasurer Date is expiration of term on Board of Directors. The Packet Status Register is the official publication o f the Asterisk indicates member of Executive Committee. Tucson Amateur Packet Radio Corporation. Explicit permission The TAPR Board of Director members “attend” a meeting, is granted to reproduce any material appearing herein, provided which is continuously in session, in a reserved area on the credit is given to both the author and TAPR. CompuServe information network. The Board encourages TAPR Membership and input from all interested members. If you have an issue you PSR Subscription Mailing Address: want addressed, or an idea for a project you would like T APR Tucson Amateur Packet Radio Corp. to sponsor, contact any Board member, or drop a note to the PO Box 12925 TAPR office. Tucson, AZ 85732-2925 Phone: 602-749-9479 To send E-mail to a CompuServe account from the Inter­ FAX: 602-749-5636 net, use the address: Office Hours: Tuesday - Friday XXXXX.XXXX0 Com puServe.com 10:00am - 3:00pm M.S.T. where the X ’s are the CompuServe ID number. Note: be 17:00-22:00 UTC sure to use a period, not a comma, in the ID number.

PSR Editorial (Only) Address: Bob Hansen, N2GDE PSR Editor P.O. Box 1902 Elmira, N.Y. 14902-1902 CompuServe: 71121,1007

Packet Status Register Tucson Amateur Packet Radio Corp. SECOND CLASS PO Box 12925 Tucson, AZ 85732-2925 POSTAGE PAID AT TUCSON, AZ.

PACKET STATUS REGISTER

ISSUE #46

April 1992

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