We put together some really cheap GPS and physio telemetry just for fun and it works great. It transmits on ham radio frequency 144.390 MHz and is used by jumpers who are licensed hams.
It can't legally be used for commercial operations, but if you could get a license for a business telemetry frequency the rest of the gear is plug and play (sensors, data decoders, radio modem etc).
Data loggers worn by jumpers do a fine job but it's fun to see live radio telemetry on the ground and if a jumper landed waaaay out we'd have the GPS position data.
We'll be flying live 1.2 GHz video at the Byron Boogie http://www.bayareaskydiving.com on Oct 16 2010. It will be relayed through a ham TV repeater on Mt Diablo to the Pacificon ham radio convention that is taking place in San Ramon.
Watch the jump telemetry on http://www.aprs.fi on October 16. Use KF6WRW as the search term, jumper 2's callsign.
I imagine commercial test jumpers sometimes use radio telemetry gear ($$$$) and hoped this post might stir up some interest in and dialog about cheap home brewed systems.
Our group did ham radio jumps at the Byron Boogie last weekend (Oct 16 2010). Telemetry gear worked great sending GPS position and altitude data and heart rate and blood oxygen levels using a pulse ox fingertip sensor and a GPS puck hooked up to an APRS transmitter on 144.390 MHz.
This time we borrowed some ATV (Amateur Television) gear from the Mt Diablo Amateur Radio Club and gaffer taped it to Beatnik's rig and helmet. It operated on 1.2 GHz and linked through the Mt Diablo ATV repeater to cover a very wide area. Ham attendees at Pacificon 2010 in San Ramon got live TV coverage of our hop and pop canopy rides from 13.5. They LOVED it. We chatted with a lot of them on 2 Meter FM simplex 146.46 MHz during the long (and very scenic) ride down.
(This post was edited by 377 on Oct 18, 2010, 3:43 PM)