HF APRS

  

In the past, I ran an HF APRS gateway on behalf of KL7AA on 30 meters, using Robust Packet as the transport layer.  It worked well enough, however using a proprietary undocumented mode over amateur frequencies left a bad taste in my mouth.  Supposedly the SCS tracker we were using at the time could handle both robust packet and 300bd ax.25 on the same channel, however I never saw any evidence of 300bd bell being decoded.  The equipment to run robust packet was also expensive, which severely limited uptake.  The killing blow came late last year, when the radio running this HF igate seemed to go deaf, and so I pulled it off the air.

 

Fast forward to this summer, and a fellow ham turns me on to HF APRS again, this time using the VARA softmodem as the transport layer.  A little research turns up WA8LMF, who has already done a lot of the low-level work needed to operate this mode.  So after work one day, I attempt a experimental igate to see if it would be worthwhile.  Within 30 minutes of operation, I pick up a beacon from WA7GMX in the Seattle area!  I definitely think this is something worth pursuing.

 

First order of business is a permanent full time igate.  I haven't quite figured out what form this will take, but I'm inclined to start with an igate at the KL7AA club station, and perhaps another at my home station after I get VHF APRS back online.  With work, it may be possible to gate stations heard over HF to VHF.

 

Vehicle trackers may be a more interesting problem to solve, but thanks to the work of KM4ACK on 73 Linux, VARA has been shown to run reliably on linux and even raspberry pi platforms.  A pi and usb gps interfaced to a mobile HF rig may be a nice tidy platform for a basic HF tracker.  We shall see. 

Ham projects for 2025

 2025 has dawned with a fresh list of aspirations for myself.  While some goals, such as a new job, are outside the scope of this blog, there are multiple items that deserve to be listed here, mostly to hold my feet to the fire.

Site Summit BBS:

 I've managed to convince holdouts on the KL7AA board to let me move forward with an upgrade/replacement of the packet node on Site Summit.  The plan is to install a full featured linBPQ based packet node with BBS, forwarding, and Winlink capabilities in its place.  There will be a 1200bd port on 145.010MHz and a 9600bd port on 440.050MHz.  Ideally, this will also be links to the Wasilla node too, although I haven't yet approached the MatSu club on this matter.

Robust Packet HF APRS igate:

 The radio running the Robust Packet HF igate on 10.1473MHz USB has apparently seem to have gone deaf, although I have not dedicated time to in-depth troubleshooting of the system.  For the time being, the igate has been pulled offline, pending future troubleshooting efforts.  The future of this system is, at this time, unknown.

Home shack master plan:

Utilizing my current Hermes Lite 2 and shack pc running Linux Mint, plus hopefully a Hardrock50 amp if I manage to save up the money, my purely personal goal is to have a fully remote HF operating position.  I also plan to bring my VHF igate back online.  I also have a SEA-222 marine HF transceiver, which, if it is stable enough, I plan to press into service as an HF packet node on 14.105MHz LSB (technically 14.102MHz USB, since packet doesn't care, but who's counting).  If all this jank actually ends up working, I may crosslink the HF packet and VHF APRS port, but that's much further down the line.

There's a lot up there, when you start dissecting each piece, and that's before you factor in other obligations, but I think I can pull it off.

~moose

HF APRS IGate

 Nothing like a simple fix to a problem you've been banging your head against for months to humble you...

As a bit of background, one of the APRS systems I manage for the KL7AA club is an HF APRS igate, running robust packet (RPR) on 30m at 10.1473 USB.  Its not my favorite mode, given its closed-source nature, but I will grudgingly admit it performs well.  Having a free software modem version available helps make it more accessible, but that's a rant for another post.

This system has been down for most of the winter, and given the harsh winter storms we've had, I believed the issue to be with either the feedline or the antenna, and began to troubleshoot.  Another club member happened to be close by, and we began discussing the issue.  It was at this point they asked 'is this cable supposed to be plugged in?'

It was the interface cable from the modem to the radio.

All winter this cable had been unplugged, making me chase my tail for months trying to troubleshoot it.  Plug it back in, and the packets immediately started to flow again.

Putting my silly moments out there helps keep me humble.

KL1V