I’m flying down to Santa Barbara on Monday to meet my family for a few days. They’re returning from a motorhome trip, and I’m lending a hand by driving their car back up to Oregon. It’s a great chance for me to complete some experiments with APRS.
The Automatic Packet Reporting System (APRS) is a digital ham radio system for broadcasting short messages. The APRS network has both a physical and an internet component: messages sent by radio are broadcast to all listening stations, and rebroadcast by all receiving repeaters; some repeaters function as internet gateways, injecting the messages they receive into the APRS internet backbone. The internet gateways also provide a limited form of routing, selectively rebroadcasting messages from the internet backbone into their local radio region.
An APRS frame contains the call sign of the sending station, and may optionally be addressed to another station’s call sign. But most APRS messages are status reports that broadcast information about a sender’s location, movement, or local weather conditions. Here’s APRS data from the Seattle area, with a great deal of it sourced from internet stations.
Following a few YouTube videos and blog posts, I’ve begun transmitting a bit of APRS location data. The simplest setup involves a smart phone, a handheld VHF radio, and an audio cable to connect the two. The smart phone collects GPS data and constructs APRS data frames, sending them out through the radio via the audio cable. And of course, an amateur radio license is required as well.
The Baofeng UV-5R, my handheld radio, is inexpensive and popular, but a little finicky for this application. I tried strapping the whole setup to my bike for a ride last week, and somehow neglected to transmit any data. This road trip will be a great chance to work out the kinks. You just might be able to follow my progress with this APRS.fi tracking link.
When I’m done, I’ll write it up. My ultimate goal is to create an APRS beacon for bike, backpack, and sailboat. I’m working on a goal-tracking server, and it would be pretty awesome if it could automatically consume this location data off of the APRS internet backbone to see when I’ve completed recurring goals like finishing a bike century or summiting a 12k+ peak.