[aprssig] New VARA-HF Softmodem A Spectacular Improvement For HF APRS

Ev Tupis w2ev at yahoo.com
Mon Jan 9 05:56:51 EST 2023

 Wow!  Congrats on the successes and thanks for the graphics as well.  Point made! :-)-Ev, W2EV

    On Monday, January 9, 2023 at 12:19:30 AM EST, Stephen H Smith via aprssig <aprssig at lists.tapr.org> wrote:  
After spending nearly the entire New Year's 3-day weekend twiddling TCP/IP settijngs, serial port emulators, sound card drivers, etc,   I now have the VARA high-performance HF soft-modem working with the UIview and APRSpoint APRS programs.  
I am using a stack of components from "VSPE" (Virtual Serial Ports Emulator) to create a serial-to-TCPIP bridge to connect the serial-only KISS output of UIview to the network (TCP/IP) KISS connection provided in the VARA soft-modem.  
For nearly 40 years, HF APRS has used classic 300-baud 200-Hz-shift HF packet (mostly on 30 meters) as it's transmission method. However, packet is a horrible mode on HF with poor immunity to noise and HF selective fading.   I've been using the "UZ7HO Soundmodem" soundcard "soft TNC" (arguably the best HF packet TNC - hardware or software) for this purpose. However, it still falls far short of modes like MFSK16 or PSK63 for weak-signal data operation.  
For about two years, I have been experimenting with using FLdigi as a KISS modem for HF APRS on both 30 and 60 meters.  60 meters tends to be a noisy band, putting a premium on data modes that can perform error-free at low signal-to-noise ratios.  My web site about this is here:
Over the weekend of the 6th and 7th of January , I conducted a road test comparing the performance of APRS over traditional HF 300-baud AX.25 packet  vs  APRS using the VARA modem on 60 meters.  This was a 500-mile round-trip from central Michigan (East Lansing area) to west suburban Chicago and back.  VARA was overwhelmingly superior - by least an order of magnitude! 
The full details, including a brief background on VARA,  are on a new page on my web site at:

 Stephen H. Smith    wa8lmf (at) aol.com 
 Skype:        WA8LMF
 EchoLink:  Node #  14400  [Think bottom of the 2-meter band]
 Home Page:          http://wa8lmf.net
 -- APRS over FLdigi Modes  --
 60-Meter APRS!   HF NVIS APRS Igate Now Operating
 Flying Digipeater!
 11 Copies of UIview in Action on One Computer!  
 Live Off-The-Air APRS Activity Maps




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