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Thanks for the reply David.

Your comment that AX.25 and PACTOR are different protocols is what I expected.

My confusion is that all of the listed stations say PACTOR none say AX.25:

I have a nearby Ham club friend N5TW, who is on this list.? He is going to try to help me this weekend, but he is not a software person, so he can only help determine if he is receiving my signal.? The problem is that the list only shows him (as well as everyone else) running PACTOR.? If Direwolf on AGWPE port 8000 is using AX.25 then how could this work?? Is there some other list of HF stations that use AX.25?? Even though the stations are listed as PACTOR do some also support AX.25?

Paul KB3PUW

On Thursday, March 21, 2024 at 07:16:02 PM CDT, David Ranch <direwolf-groupsio@...> wrote:

Hello kb3puw,

I am trying to use PAT to do HF Winlink.? I got PAT to work with telnet over the internet, so I know I? am setup from a Winlink standpoint.? I have successfully gotten Wirewolf to work with Xastir for APRS, so I know Wirewolf is basically working.

Ok.. was that via the emulated serial I/O approach or via the AGW I/O approach.? I would recommend the AGW approach.

I have read some fuzzy articles on using Direwolf to interface with my rig to do RF Winlink.? I have not tried VHF FM Winlink yet, at the moment I am trying to do HF.? I know that most HF Winlink repeaters support various versions of PACTOR.

PACTOR is not supported by Direwolf.? It's only supported via SCS hardware TNCs.

I know that Direwolf can work with AX.25. I was able to get PAT to connect to AGWPE port 8000 of Direwolf and it appears to be trying to form a link. My transceiver is activating and sending something but so far I have not made a connection.

Good!? It sounds like your issue is just on audio tuning and then the rest is up to how much RF power your radio has,? how good your antenna system is, HF propagation, etc.

I am having trouble both conceptually and practically understanding how the pieces fit together.? The best I have been able to make of things is that Direwolf does PTT rig control and does the FSK modulation through a sound card that is fed to the transceiver.? I know that PACTOR is a resend type fault tolerant communications protocol used for Winlink on HF.? I am not sure where or whether AX.25 fits into this and how or whether PACTOR relates to AX.25.? There must be some FSK frequency configuration somewhere, but I don't know how this works.

PACTOR and AX.25 are totally different technologies.? When PAT talks to Direwolf via AGWPE, it will ask Direwolf to create a connection to whatever callsign you specify.? This then assumes you configured Direwolf to use a 300bps AFSK modem.? Per the Direwolf User Guide section 9.2.4, you can enable some advanced features to improve the link reliability with things like:

?? - Multiple parallel decoders for off frequency stations and maybe use different frequency offsets if the remote station uses them
????? - Here is an example using the standard 1600:1800 offsets, 7 parallel decoders, lower the CPU loading to 1/4 for say running on a Raspberry Pi, and us the 300bps "B" style "SSB" modem with multiple slicers:

??????? MODEM 300 1600:1800 7@30 /4 B+


?? - Consider enabling FX.25 transmit support to add forward error correction if the remote stations support it (some do, most don't).? This is detailed in Section 9.3 and you can try with the setting of 32 but this depends on how much FEC you want (but slows down the connection throughput):

????? FX25TX 32
??

?? - Maybe try enable some bit fix repairs (sometimes can make things better, sometimes worse).? The "ax25" parameter says to only use basic AX.25 heuristics and not include any APRS specific heuristics:

? ? ?? FIX_BITS 1 ax25


?? - Direwolf defaults to trying to make AX.25 v2.2 connections but many HF stations don't support this.? For the ones that do, it can really help things be faster and more reliable.? Direwolf will try making initial connections with the "SABME" packet where the "E" mean enhanced.? After three tries w/o success, it will step down to to the v2.0 specification with "SABM" packages.? I you want to avoid this initial three tries, you can either configure each remote callsign-ssid in the direwolf conf file like the following:

????? v20 KI6ZHD-1

??? or you can outright disable v2.2 attempts for ALL stations with:

????? maxv22 0


--David
KI6ZHD