APRS Cave-Link utilizes the amateur radio’s Automatic packet Reporting System (APRS) inside caves to get their setting data (and other messages) out.

Imagine that you’re coordinating a big scale search-and-rescue objective in a cave. You requirement to understand where all your groups are, as well as whether or not they’ve discovered anything. however exactly how do they all interact to the command center?

You’d assumption radio, however you’d assumption wrong. Radio doesn’t propagate well whatsoever in a labyrinth of twisty passages, all alike; rocks take in radio waves, particularly in the VHF/UHF variety that’s finest fit for many little radios. In the past, you’d run cable as well as transmit along it. This short article runs with the choices in detail. however adding miles of cable to your already heavy caving as well as climbing gear is a nuisance or worse.

Some experiments by groups of amateur radio operators, as well as cavers, with APRS repeaters objective to modification that. Digipeaters, as they’re understood in the APRS world, take an incoming message as well as ahead it on again. On each successive hop, the station that got the signal appends its name to a listing of paths that are sent together with the message, which assures that the message propagates however doesn’t get repeated around permanently in a loop.

Digipeaters as well as battery packs are dropped, in Hänsel as well as Gretel fashion, as the cavers work their method with the cave. The technique is to make sure to location one repeater before you’ve completely lost the radio signal from the previous one, of course. however the APRS Cave-Link job got one mile’s worth of transmission in Mammoth Cave without utilizing wires at all. That’s not bad!

Now, GPS still doesn’t work underground, so the cavers requirement to bring an precise map together with them as well as keep track of their own location. however even getting essential messages (“we discovered him!”) passed around inside a cave atmosphere is sufficient of a challenge.

We’ve seen APRS utilized for tracking high-altitude balloon payloads, as well as we can’t assist however question if the exact same interest to weight-saving that’s demonstrated in these diy versions wouldn’t likewise be helpful in a caving context.

Have you made any type of awesome networks of APRS links? Under adverse conditions? let us understand in the comments.

And thanks [Travis Goodspeed] for the unintentional tip.