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PSK63 HF APRS is Back !


WA8LMF
 

Ever since APRS Messenger was discontinued, I have been lamenting the loss of a vastly superior (compared to 300 baud AX.25 packet) HF APRS transmission mode. 

I discovered that the FLdigi multi-mode sound card app can act as a KISS modem to external applications.   After a considerable amount of testing, tweaking and experimentation, I have got FLdigi to work with various APRS clients on PSK63, MFSK16, 8PSK-250 and other modes provided by FLdigi.

1)   FLdigi provides a KISS output over TCP/IP -- not a virtual serial port. This means that either:  Your APRS client must support KISS-over-IP -- Or that you do an IP<-->serial conversion for older com-port-oriented APRS applications such as UIview.   


2)   The IP-to-serial conversion can be doe with the freeware utility "com0com" and it's companion application "com2TCP"



3)   I am now operating FLdigi-mode igates on 30 meters and 60 meters  24/7, from my QTH in East Lansing, Michigan (center, more-or-less of the lower peninsula of MI.  

On 30 meters, I an using the same channel center as the classic 300-baud AX.25 packet APRS.  On 30M, place the radio on 10.147.60 MHz USB, which will place FLdigi modes with 1700 Hz audio center tones exactly on 10.149.30 MHz RF -- i.e. midway between the 10.149.20 / 10.149.40 tones of AX.25 packet APRS.   

On 60 meters, I am using US 60M "channel 5" (carrier freq of 5.403.50 USB). 


4)   The setup on each band is a Yaesu FT-857 with a 500 Hz Collins CW filter.   This is just wide enough to pass the conventional 300 baud HF packet APRS, and also the narrower FLdigi modes such as PSK63, MFSK16, 8PSK-250, etc.  Don't try wide modes such as Olivia 1000 or MT63 -- they just won't fit through the 500 hz passband.


5)   Full details on setting various APRS clients to work with FLdigi (including the IP<-->serial bridge if needed) are here on my website:

    <http://WA8LMF.net/FLdigiAPRS>



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  --
   <http://wa8lmf.net//FLdigiAPRS/index.htm>

60-Meter APRS!   HF NVIS APRS Igate Now Operating
   <http://wa8lmf.ddns.net:14447/>

Flying Digipeater!
   <http://WA8LMF.net/FlyingDigi>

11 Copies of UIview in Action on One Computer!  
Live Off-The-Air APRS Activity Maps
   <http://wa8lmf.net/map>







WA8LMF
 

On 2/14/2021 4:54 PM, WA8LMF via groups.io wrote:

Ever since APRS Messenger was discontinued, I have been lamenting the loss of a vastly superior (compared to 300 baud AX.25 packet) HF APRS transmission mode. 

I discovered that the FLdigi multi-mode sound card app can act as a KISS modem to external applications.   After a considerable amount of testing, tweaking and experimentation, I have got FLdigi to work with various APRS clients on PSK63, MFSK16, 8PSK-250 and other modes provided by FLdigi.


Forgot to also mention:

The gateway page to my various mapping APRS igates/webservers for the various bands and modes is:

   <http://WA8LMF.net/map>




Kenny Witt
 

Great!  Been working with com0com for years.  Lots of possibilities there

Kenny, KC4OJS 


On Feb 14, 2021, at 5:11 PM, WA8LMF via groups.io <wa8lmf@...> wrote:


On 2/14/2021 4:54 PM, WA8LMF via groups.io wrote:

Ever since APRS Messenger was discontinued, I have been lamenting the loss of a vastly superior (compared to 300 baud AX.25 packet) HF APRS transmission mode. 

I discovered that the FLdigi multi-mode sound card app can act as a KISS modem to external applications.   After a considerable amount of testing, tweaking and experimentation, I have got FLdigi to work with various APRS clients on PSK63, MFSK16, 8PSK-250 and other modes provided by FLdigi.


Forgot to also mention:

The gateway page to my various mapping APRS igates/webservers for the various bands and modes is:

   <http://WA8LMF.net/map>




Chris Moulding
 

Good to hear that FlDigi can be used as a KISS modem.

I was really disappointed when I had to remove APRS Messenger but I could find no way to run the Visual Basic 6 programming software on Windows 10 to fault find the problems running it on Windows 10.

One question about running FlDigi in KISS mode. One of the strengths of APRS is that there is error detection in the protocol used on VHF 1200 bd and HF 300 bd that rejects packets with errors.

In APRS Messenger I added a simple CRC check to prove that the received packet was the same as the transmitted one and used it to reject or not igate packets with errors. I added an option in the program so that it would display packets with errors on the display so that a human operator could read an make sense of packets some errors due to fading on HF.

I've been having a quick read of the AX25 KISS protocol and I can see that it can detect framing errors but nothing about errors in the text sent over the air.

Stephen, can you confirm from your testing that it's rejecting packets with errors in the transmitted text?

It's an important point because if it allows packets with errors through then it would allow garbage to go to the APRS-IS internet system with incorrect positions and at worst case incorrect callsigns.

Regards,

Chris