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Packet Modes ALE So Let's Get Started Good Frequencies or 200 baud FSK with a long packet length and package is SkySweeper (www.skysweep.com). (for the first time) data compression. It’s now While some modules work better than others, found in most free and cheap multimode decod- it provides a very full set of linkable decoders, ing programs. Unfortunately, it’s hardly ever used analyzers, filters, and other goodies that are great anymore, except for calling. fun to hook together and tinker with. Most real-world users have shelled out for the For Mac, there’s always Chris Smolinski’s expensive and extremely sophisticated PACTOR- MultiMode for OS-X. This program’s been around II, and its firmware upgrade called PACTOR-III. forever, and it does a lot of nice things for the price These can choose between a truly remarkable ($89 US from Smolinski’s site, www.blackcatsys- number of FSK and PSK schemes, adapting in tems.com). real time to channel conditions. It’s available only Any of these programs will have enough from the SCS company and its licensees. bells and whistles to keep you experimenting for Most HF e-mail systems use PACTOR-II months. Since you have a computer, use it and or one of its custom variations. Some computer Google to find more software and tips on how programs and modems can indeed receive these, to use what you have. There’s no such thing as but at a cost far beyond the means of most hob- knowing it all. byists. ❖ Good Frequencies ❖ ALE W1AW is the well-equipped headquarters ALE is not what you get at the local pub. station of the American Radio Relay League, a It’s Automatic Link Establishment, a complex large ham radio association. It broadcasts a full system used by most of the world’s militaries. schedule of bulletins in Morse, RTTY, Ameri- It’s designed to make HF as easy to use as other can Standard Code for Information Interchange radio bands, by automating much of the grunt work (ASCII, a 7-bit descendent of ITA2), and AMTOR of picking frequencies, finding the best ones for (Amateur Teleprinting Over Radio, received same different participating units, and adapting to con- as SITOR). Times and frequencies are available at A typical commercial use of PSK is the tinuously changing propagation conditions. Hams www.arrl.org/w1aw.html . High-Frequency Data Link (HFDL) mode used are also experimenting with ALE, with equipment for air-to-ground traffic. A typical military use is modified for its fast channel hopping. STANAG 4285, a wideband whooshing sound de- ALE has done a lot to put military units in fined in a Standardization Agreement for members the field back onto HF, giving that part of the of NATO (North Atlantic Treaty Organization). hobby a new lease on life. It’s amazing what can Both systems can change PSK variants, and there- be heard “sounding” (sending identifying beacon fore speeds, to suit a particular channel. transmissions for propagation evaluation). Hams have really gone to town with PSK. A good introductory program, if you can There are new modes yearly, mostly using direct get it to work, is Charles Brain’s old PC-ALE for keyboard to keyboard communication. Tuning to Windows up to XP (not Vista). His web site has 14070 kHz any time the band is open will produce gone away, but various people are still maintaining multiple warbling sounds often sounding like a different versions of this one. ALE is also included plague of locusts. This is PSK31, a slow, very nar- in most multimode packages, though usually rowband mode well suited for casual conversation without PC-ALE’s ability to scan channels using using personal computers. instructions given over the serial port. 14070 kHz nearly always has at least one PSK31 contact going during daytime hours. For ❖ ❖ other PSK modes start at 14070 kHz and move Packet Modes So Let’s Get Started higher in frequency. Going higher yet, RTTY and “Packet Radio” is not a modulation scheme. As we’ve noted, if you have a radio and a packet radio can be heard all the way up to 14105. It’s a protocol for passing data between a sending computer, you’re most of the way there. You don’t At night, some PSK31 may be heard on 7070 and receiving station. Instead of sending one or a need an interface -- that’s for transmitting. You kHz. few characters at a time, it assembles them into need to connect the earphone or recording output Hamburg Radio, the German meteorological larger, consecutively numbered, error-checked, of the radio to the input of the computer sound station, broadcasts continuous RTTY, which is data units called packets. card. In most cases, that’s it. heard worldwide. Assigned frequencies are 4583, In most packet protocols, the receiving sta- Of course, you’ll also need software. There 7646, 10100.8, 11039, and 14467 kHz, though tion either acknowledges valid packets or asks that are hundreds of downloads, ranging from great RTTY dial frequencies can vary up to 2 kHz either to wretched, though most are in the middle some- way. where. Most are for Windows, though there are a CFH, the Canadian Forces meteo station, few for Mac and Linux. sends weather faxes on the hour and fills in the Windows users have an additional issue with rest of the time with RTTY weather. Assigned Vista, which completely changed the way the frequencies are 4271, 6496.4, 10536, and 13510 operating system handles the sound card. A lot of kHz. older ham radio software works unpredictably, if SITOR-B is still available from the world’s at all, with Vista. coast guards. Mediumwave fans will want to check they be sent again. Bad channel conditions simply One truly impressive download for Windows the schedules and chase NAVTEX bulletins on 518 cause more retries. This makes HF packet very (including Vista) is called MultiPSK. Most of kHz. On HF, several powerful US Coast Guard error-free, but potentially also very, very slow. its features work in the free version. The user stations use 8416.6, 12579, 16806.5, and 22376 An interesting commercial system aimed at interface is improved slightly in version 4.10. It’s kHz. The full schedule is at www.weather.gov/ combining packet’s robustness with the better HF fast and effective, but certainly not pretty. What’s om/marine/hfsitor.htm performance of SITOR is called PACTOR. This pretty is the way it produces nice clean decodes The US Air Force has a global network of can stand for Packet Teleprinting Over Radio, of many PSK and non-PSK modes. large stations that use ALE; 9025 kHz is a sure though its European inventors say it refers to a There are too many other free or low-priced hit, if you wait long enough. Latin word for “the mediator.” multimode programs to list here without leaving Now, let’s log some digital and send it to The slowest version, PACTOR-I, uses 100 out worthy software. One popular medium-priced Utility Logs! See you next month. January 2009 MONITORING TIMES 31.
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