downlink system for high altitude attempts? ideas?

[aaronredbaron]

My friends and I plan to take our patented airship to record hights for lighter than air. we need a downlink system that can transmit at least 2 and preferably 5 channels of info back to the ground ( camera, altimiter, temp, gps, envelope pressure ). if anyone has ideas on such a system either commercial or custom it would be great. the current record is held by the japanese at 26,000 feet with a 141 foot long ship that offered no control other than a burst valve. we are going after this record with a 20 foot tall ship with full control. if anyone has experience with either the downlinks, record attempts or anything else that might help out we would welcome any input.
thanks
Aaron "big red baron" Shell

[Mr.RC-CAM]

Cyber-flyer has been at +20K feet AGL. His telemetry data consists of a stock GPS that is viewed in the cockpit via a second camera (activated from the R/C Tx). His video transmitters are 900Mhz and a 2.4Ghz (~1 watt) that are paired up with a custom cross-dipole and diversity Rx antenna system.

Full details: http://www.cyber-flyer.com/

RC-CAM