Tracking a long-duration high-altitude balloon is a different kinda problem.
For a typical ARHAB flight, we use standard APRS beacon packets on 144 MHz, which are collected from most anywhere and relayed to the APRS-IS database. A long-duration flight is often associated with a trans-oceanic attempt, and VHF APRS just won’t get it done. So, we turn to the HF digital modes and get help from multiple receivers scattered around the world. With enough volunteer listeners, someone’s location will have good conditions and can copy the position beacons. Thanks to a customized version of the FLdigi code (called dl-FLdigi) and a website called SpaceNear.US – there is now a new network for ingesting and processing this distributed telemetry collection.
(reference links at the end of this article)
This map shows a recent test flight, where WB8ELK used Domino EX16 encoding on his telemetry packets using a 200 mWatt transmitter on 7.077 MHz. His GPS receiver/HF transmitter/battery pack totaled about 1 pound. The balloon had a deliberately slow ascent rate, to keep it aloft for a longer flight. The launch was late in the day to avoid any solar heating. This balloon package travelled thru the dark of night, and landed in the middle of an artillery shooting range at Fort Stewart just west of Savannah GA. The map above shows the locations of the various operators that were listening for the beacon transmissions, using the dl-FLdigi program, and the path of the full flight.
Without going into a lot of detail here, I’ll provide some links, and encourage you to participate in these flights. This program makes it really easy.
The more listeners we have, the more likely we can track the entire flight.
There are plans for a trans-Atlantic attempt in Jan 2011.
Stay tuned for future details . . . . .
Links of relevance :
ARHAB = Amateur Radio High Altitude Balloons
APRS = Automatic Packet Reporting System
APRS-IS = APRS Information System (used a lot for vehicle tracking)
dl-FLdigi = customized program with special HAB mode (JamesCoxon)
fl-digi = linux/Windows program for soundcard modem communications
SpaceNear.US = tracking website
WB8ELK = a world-reknown pioneer in ARHAB sciences
WhiteStar = upcoming trans-Atlantic balloon attempt