Sound Card Packet

1200 and 9600 baud can still serve useful in point-to-point portable emergency situations where line of site may be hard to achieve. However, an emphasis on installing permanent HSMM antennas at key emergency locations should be encouraged for preparedness.   CQ Editor Rich Moseson, W2VU talks about packet's remarkable comeback and its emcomm applications in a April 2000 RAIN report.  

There have been a couple subsequent  articles on how low cost sound card packet, and has provided somewhat of a rebirth to conventional packet radio.

There are at least three new versions of Packet Radio soundmodems using different features like FEC, bit guessing and now written in JAVA.

They also can support the higher speeds like 2400 or 4800 with simple radio audio connections.

I'd suggest that the soundmodem will become the standard interface in the near future.  It's much better than it was.  Not long ago the rule of thumb was that if you wanted a data TNC - get a real one and don't expect a soundmodem interface to be reliable.  That's changing.  A common standard of measurement is the number of packets decoded from Track 2 of WA8LFM's TNC test CD obtained at:

Generally, I think hardware TNC's are/should be a thing of the past. Paying over $40 for something that can be done with a sound card these days, all for 1200 baud is just illogical.

One of the first Multi-platform Sound Card Packet Radio Modems was coded by Thomas Sailer, HB9JNX/AE4WA.: 

- Soundmodem for Linux -

However, this Baycom version is very dated,  as it first debuted in 1998.  Thomas Sailer, HB9JNX, who developed the sound card drivers, provided three ways to key the transmitter, using either a serial port, parallel port, or the game port.

- FlexNet for DOS and Windows -

The 2009 CQ Magazine Sound Card Packet article also references the December 1999 CQ VHF Digital Data Link column, with a republished an article by John Hansen, W2FS, about using PC/FlexNet's sound-card utility.  It also appeared during Spring 1999 in the TAPR Packet Status Register, titled "Packet Radio for Less than $10".  This software runs under both DOS and Windows95. 

- AGW/PE for Windows -

 The AGW Packet Engine written by George Rossopoulos, SV2AGW.  For a very detailed, step-by-step guide to setting up AGWPE and some troubleshooting tips, visit the Sound Card packet web page built by Ralph Milnes, KC2RLM, at:

- JavaAX25 for all platforms -

This is one of the newest sound modems.  Written by Sivan Toledo, 4X6IZ of Israel.

- UZ7HO for Windows -

Andrei Kopanchuk’s software modem.  Referenced in the July/August 2012 QEX article.

- Frank Perkins’, WB5IPM AX.25-SCS -  

Also Referenced in the July/August 2012 QEX article. Frank Perkins, WB5IPM. “DSP Programming using DirectSound and MFC/VC++" - Proceedings of the 22nd ARRL and TAPR Digital Communications Conference, Hartford, Connecticut, September 2003, pp 140-149.

A Windows installer for the AX25-SCS DSP TNC program can be downloaded here. This will allow the installation of AX25-SCS and the drivers needed for Windows PCs.

- DireWolf for both Windows and Linux. -

Dire Wolf was designed as a sound card TNC for APRS.  It uses a AGW interface and KISS port compatible. - The KISS protocol is available thru a fake serial port (“pseudo terminal”) for older applications that only know how to talk to a TNC thru a serial port. 

- Oscar Delta for AX.25 -

- Extmodem, an AX25 Open Source Soundcard Modem -

Alejandro Santos, LU4EXT of Argentina, wrote this based on code from Thomas Sailer's multimon and Sivan Toledo's javAX25.



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