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
