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.
