2. General Description of the DTR-MS 3

DTR MS

Digital-Tape-Recorder for MS

Manual

1. Introduction...... 3 1 1.1 Information about meteorscatter...... 3

2. General description of the DTR-MS...... 3

3. Installing the DTR-MS...... 4

3.1 Hints for the electrical installation...... 4 3.2 Diagram on the necessary connections...... 4 3.3 Power supply...... 4 3.4 Operating the DTR-MS...... 5

4. Specification of push-button keys...... 5

5. Description of functions...... 6

5.1 Recording the AF-signals...... 6 5.2 How to mark a burst...... 6 5.3 Playback,...... 6 5.3.1 Playback, simultaneously while recording...... 6 5.3.2 Replay after maximum recording time...... 7 5.3.3 Playback by using info marks...... 7 5.4 Playback- using a different speed...... 7 5.3.5 Playback using a different modulation...... 8

6. Appendix...... 9

6.1 Adjustments...... 9 6.2 Configuration of DIP-switches when switching on...... 9 6.2.1 Configuration of standard speed...... 9 6.2.1 Configuration of the standard modulation...... 9 6.2.4 Scaling of the counter:...... 10

7. Technical information’s...... 10

1. Introduction

First of all, we wish to thank you for buying the digital tape recorder for meteorscatter (DTR-MS) 2 We are sure that you will make many successful MS-contacts using this gear. We have taken all care in drawing up this instruction manual. In case that there are some details explained insufficiently please feel free to contact us and we will try to improve the manual. Any suggestion will be very much appreciated.

1.1 Information about meteorscatter

It can be possible that by studying this manual further questions might arise. Quite often, these questions are not related how to handle this equipment. Instead, they refer to matters of the physical background of meteorscatter or how to operate via meteors. It can not be the purpose of this manual to explain these items. It will be the best to contact an active meteorscatter operator to discuss these problems. If you don´t know anyone in your near, we should be glad to provide you with calls of stations who are active in your area. Of course, we are also able to provide with the desired information. ....Please, feel to ask! Send us a letter, give us a phone call or write some lines via packet radio to: VHF-DX-Gruppe DL-West (c/o DL8EBW @ DKMWX.#NRW.DEU.EU) Guido Jünkersfeld, Geibelstr. 13, 42327 Wuppertal

2. General description of the DTR-MS

The DTR-MS is a portable digital instrument enabling you to record AF-signals over a maximum period of about 155 seconds (at a sampling rate about 6,6 Khz). The DTR-MS provides the possibility to check the received information while still recording or when the recording-time is over. In both cases you are able to decode signals at normal or reduced speed - in normal or mixed modulation with the CPU. The mixed mode can be advantageous if you have to listen to a signal at reduced speed and subsequently the tone-frequency is to low for your ear. By being so small-sized and sensitive the DTR-MS is an efficient alternative to tape- or cassette-recorders for the meteorscatter interested amateur, especially going on expeditions thereby reducing weight. The complete electronics of the DTR-MS is in a handy box of anodised aluminium. To operate the gear it is only necessary to know the 7 different keys on top of the box. All information received from the CPU are shown the big 7-segment LED-display. The external voltage required lies between 10 - 15 V DC, so you might use the car-battery or an adapter which is used in the video-business. After switching on the power to the DTR-MS , you only have to connect the AF-in and AF-out - and then, you can step on the gas - - - GOOD REFLECTIONS!!!

3. Installing the DTR-MS

3 3.1 Hints for the electrical installation

Like the standards in high-frequency technics, please connect the DTR-MS with as short lines as possible! Avoid vicinity of high voltage lines or strong magnetic fields for it could effect the performance of the DTR- MS negatively. Be sure that the power supply lines and the AF lines have good contact to the connection jacks. Always check the right polarity to avoid problems.

3.2 Diagram on the necessary connections

The DTR-MS has only 3 plug-ins. Please connect the lines as shown in the diagram below. Give as much AF-signal from your transceiver into the AF-in-jack till the point where the AF-output will not increase anymore. That is the optimum signal volume for AGC (automatic gain control)! DTR-Versions delivered after Feb. 15. 1995 will have a small LED at the edge of the display (see fig.2): This LED is „OFF“, if AF-input is correct. * The optimum for the received tone lies between 800 Hz and 1200 Hz (due to the input filter). * former versions can be modified

Power supply AF-in AF-out

3.3 Power supply

The DTR-MS works with an internal power stabilisator circuit. Therefore, it is possible to use a power supply between 10-15 Volt DC. The maximum current needed amounts to about 350mA, so that you are able to use a simple AC/DC-adapter which is used for video or phono applications. An internal diode protects the DTR-MS against polarisation changes. Please switch off power supply before pulling DC connector.

3.4 Operating the DTR-MS

The DTR-MS is constructed as a portable recorder but can also be used in the home shack, of course. It can be used within a wide range of temperatures and surrounding-conditions. Please be sure to have a solid stand for your DTR-MS without strong vibrations, swinging, or other harmful factors to electronically equipment. 4 4. Specification of push-button keys see fig. 2 button < « > rewind button playback (green LED above) button < » > forward button record (red LED above button mark burst button select speed button select modulation

The function of these 7 buttons and their consequences will be explained in chapter "5".

AF-Input Control-LED

5 5. Description of functions

With the recording system DTR-MS you have bought a system to record and replay AF signals up to 2,5 minutes. It is recommended to learn all functions quite properly, to get efficient to operate MS:

5.1 Recording the AF-signals

1f you want to switch the DTR-MS into the recording mode, you have to push the buttons and at the same time! This double function of keys (the only one, up to now) is necessary to avoid unintentional overplaying of old records. When you push and together, the display will show undefined values, if the A.F. input is connected - this is not a fault! When, the AF input is disconnected the display will show a number around 128. (Adjustment of AGC). After releasing the buttons the counter will go to 000 (0-150 or 0-989 depending, on the standard settings) The red LED above the button indicates that you reached the recording mode. During, the record, you are able to track the slightly filtered input signal at the AF output.

5.2 How to mark a burst

In operating meteorscatter mode it is very important to know at what position of your record you can find quickly the information of your partner. So, you have to set an information (counter)-mark directly there, where you have heard the reflection. The DTR-MS has such a possibility. Using your old tape recorder you always had to watch your tape counter and write down the number were the burst occurred. With the DTR-MS you only have to push an info-mark (short and the CPU makes a special digital sign in front(!) of the burst. This only works when you push immediately the button when you hear the signal. The CPU will take 'into account your reaction time and the setting mark will be some milliseconds in front of the information. The display will show you a name for this setting mark for about 1 second (e.g. -05) With this number the place in which the burst occurred is clearly defined and can be found later without any difficulty! We recommend to train a bit on how to set these information marks, but after some skeds you will have no problems with it!

5.3 Playback,

The playback-function can be used simultaneously during recording (then it is necessary to listen to the recorded AF on the transceiver speaker) or after the 155 sec. of recording (end of recording time). The AF-output of your headphone is adjustable by the only extern potentiometer at the left side of the DTR-MS.

5.3.1 Playback, simultaneously while recording

If you push the button while recording you will get the signals from the start of the recording time directly to the output! (counter start with 000). The green LED above the button then indicates that you are in the playback mode. The red LED above the button indicates that you are still recording simultaneously in the background. You are still able to give setting marks to the CPU (using ) if you recognise some burst during the time you listen to the replayed information (check second speaker or watch the S-meter of your receiver).

5.3.2 Replay after maximum recording time

6 When the 155 seconds of recording-time are over the counter will stop at the scaled value (989 or 155) and the red LED above the button will be extinguished. Now the complete information of 155 seconds will be stored in the RAM as long as you start again the record mode (push and together) or you shut down the DTR-MS.

If you wish, you can get all the information from the beginning of your record by pushing the button. The green LED (above then indicates that you are in the playback mode. The display shows you the present position of your recording. The buttons < « > and < » > can be used to go quickly to other positions of your recording.

5.3.3 Playback by using info marks

As shown in chapter 5.2, the DTR-MS has the provision to store setting marks (up to 30!) in form of an recorded information. So, if you used that way to mark a burst, you are able to find this position by the recorded information quite easily. Then, you are NOT to go into the playback mode «PLAY». You must remain in the recording-mode or in the standby-mode (end of recording-time after 155 sec.).

At first, you have to push the buttons < « > or < » > and the display indicates your setting mark number (e.g. -05). Then, you have to switch into the playback mode (push button ). After some milliseconds you will hear the information coming out of the noise, if your setting mark was sent correctly. Otherwise use the < « > button and search over the last seconds of your record... perhaps your reaction had been a little bit slow when the burst occurred (In long MS-nights this can happen, hi). Do this search only in the playback mode, because, otherwise, if you are going back into the standby mode, you only will scroll between the mark numbers. By-the-way, a beginning-mark (I--) and an end mark (--I) will always exist.

5.4 Playback- using a different speed

For meteorscatter operation it is necessary to use higher cw speed than normal (at present time mostly up to 1500...2000 lpm). It is up to you by what factor you reduce the speed. You have the choice to reduce the speed by 1/2 up to 1/16 * (e.g.: 2000 lpm / 16 = 125 lpm). Anyhow, it doesn't matter in which mode the DTR-MS is just working, you are able to change the speed with the button . Push that button and the speed will -go down one more division factor. The speed rate is always shown for 1 sec. on the 7-segment display when you pushed the button . If you hold the button longer than 300 ms, the speed will step down continuously ( "scrolling" ). The last speed-rate will as long persist until you disconnect the power or until you change the factor yourself. * 1/22, 1/30 for DTR-Versions delivered after Feb. 15. 1995

5.3.5 Playback using a different modulation

7 If you reduce the speed-d of an AF-signal you also reduce the tone frequency by the same factor. Therefore, you are getting, quite quickly to the end of audible frequencies (approximately 300Hz) When using a tape recorder, the difficulty is normally solved by the use of an up- converter. This circuit mixes the reduced AF-signal with a sidetone. But, that brings a mix-loss of about 3-6 dB! In the DTR-MS you have a digital circuit which is able to calculate the optimum mix after you reduced the- speed. Therefore you will not have any mix-loss! The mixing-factor for the desired tone is determined by you with the button . After you pushed the- button the DTR-MS is in the playback mode,. Now you are able to change the output tone by pushing, the button . The factor of the mix will be: PLO = no mix, PLl = input tone x 2, PL2 = speed correlated output tone and PL3 = input tone x 8 The factor will not always be exact due to the calculation of the CPU for an optimum mix. It depends heavily on how far you reduce the speed. If you hold the button, longer than 300 ms the PL-factor will step down continuously ( "scrolling" ).The mix-factor will not change as long as you turn off the power or you change the factor by yourself.

A simple example: We have to decode a CW MS highspeed signal with 1,2 KHz tone-frequency and 1000 lpm The speed should be reduced by the factor 12 and the output should be provided in a good to copy tone.:

speed frequency 1000 lpm / 12 1200 Hz / 121 83 lpm 100 Hz

The speed of 83 lpm is to copy orderly but the tone of 100 Hz in the modulation "PLO" will, hardly be audible. In this situation it will be the best to select the factor 8 ("PL3"), which will provide tones of 800 Hz at the AF output!

83 lpm 100 Hz x 8 83 lpm 800 Hz

5.3.6 First results with the DTR-MS The idea of building the DTR-MS was born in the 120 hour BCC-MS contest 1993. A group of operators around DL8EBW & DF7KF worked only with one audio tape-recorder and used a lot of audio cassettes as well as suffering, from a deformed tonehead. Again, the CT expedition of DF7KF in the year 1994 had the same problems with these audio tapes in their pile ups. To be honest, that might have been good luck for the MS- community, for after returning home Dithmar, DF7KF, was fed up with these problems and decided to develop a gear which later turned out to become the DTR-MS. The first both prototypes were realised in June 1994 and since then DF7KF and DL8EBW tested them in all their ms contacts. A lot of changes in both the hard- and the software have been undertaken since that time. DL8EBW worked more than 70 hours of MS with it and always has some new ideas. The last big test for this instrument were the BCC 1994 and the Quadrantid-shower 10 different well known MS-ops used the DTR and gave a very positive feedback. Of course DF7KF received a lot of suggestions what could be improved in the future and he should be glad to get also your comments and suggestions. He shall try his best to realise all feasible improvement suggested.

6. Appendix

8 6.1 Adjustments The DTR-MS is completely adjusted when leaving necessary to adjust the factory! If it is necessary to adjust the reference voltage of the AD/DA you have to adjust the only variable resistor on the analogue board. For this purpose please disconnect the AF-input jack thereby grounding the input (short circuit to ground, inside of the connector!). Push the button and the LED display has to show about 128 (+/- 5)- otherwise you have to adjust the trimmer to this value. If this value is correct the auto-recording system try to adjust to the optimal results of full 8 bit!

6.2 Configuration of DIP-switches when switching on

At every first switch on of the instrument, the DIP switches on the digital board will be checked by the CPU. With these DIP switches you have the possibility to configure your DTR-MS. If you change a DIP switch during normal operation, there will be no result of a change.

6.2.1 Configuration of standard speed

The configuration for the standard speeds is defined as follows: (in normal operation use

S1 off- S2 off- S3 off = 1/1 normal speed S1 on - S2 off- S3 off = 1/4 of the record S1 off- S2 on- S3 off = 1/6 of the record S1 on- S2 on- S3 off = 1/8 of the record S1 off- S2 off- S3 on = 1/10 of the record S1 on- S2 off- S3 on = 1/12 of the record S1 on- S2 on- S3 on = 1/16 of the record

6.2.1 Configuration of the standard modulation

The configuration of the standard used modulation is defined as follows: (In normal operation use

S4 off - S5 off = no CPU processed modulation S4 on - S5 off = modulation factor 2 S4 off - S5 on = speed correlated AF output tone S4 on - S5 on = modulation factor 8

6.2.3 Configuration of the standard sample rate:

At delivery the sample rate of 6,6 KHz is used.

S6 off - S7 off = abt. 6,6 KHz (Normalmode) S6 on - S7 off = abt. 10 KHz S6 off - S7 on = abt. 8 KHz S6 on - S7 on = abt. 4 KHz The internal filter is specified for the normal mode (6.6 KHz!)

9 6.2.4 Scaling of the counter:

S8 off = counting in seconds S8 on = counting 000-989 (989 full)

7. Technical information’s

 sampling rate: abt. 6.6 KHz (*)  RAM: 1 MB  max. Recording time: abt 155 seconds (*)  max. Setting marks: 30  speed: variable (l/2,1/4 1/6,1/8,1/10,1/12,1/16 add. 1/22, 1/30 after Feb. 15.  Modulation signal mix (up converter), 4 steps (no mix-input, x2, speed-cor., x8) e.g.: input tone = 1000 Hz speed 1/10 = 100 Hz modulation 8 = 800 Hz out  special feature: record/play possible simultaneously  input: AF-out of the receiver  input level: AGC, CPU processed 8bit  AF-output: abt. 500 mW (headphones or little speaker)  keyboard: 7 keys  display: 3 LED - 7segment-display  display-info: counter in seconds(*) - or 0-989  power supply: ext. pwr supply 10-15 Volt DC abt 350mA  housing: aluminium case with all necessary connections  dimensions: abt. 170 x 100 x 45 mm (like TNC)  weight: abt. 500gr.

(*) used as standard after leaving DF7KF

Technical changes reserved. DF7KF D.Daude 20.01.95