Ethernet Bridge for Communicating with a Rocket

I've been thinking lately about the problem of transmitting data from a high powered rocket to a ground station. Many people put cameras, GPS
recievers, altimeters, and other telemetry devices on their rockets and in some applications it is useful to view this data in realtime. A solution that occured to me recently was to use a wireless ethernet bridge that operates in the 900 MHz or 2.4 GHz range (as made by AvaLAN for example http://www.avalanwireless.com/product_list.htm ). Note that these devices are different than your run of the mill 802.11 wireless access points and have ranges up to 40 miles! With a small linux based computer onboard the rocket (http://www.gumstix.com /) various devices could be connected to the ethernet bridge.
My simple question is whether this though has occured to any of you and if so, how did the final product work out and what was its performance like? Thanks!
-Zach Bailey MIT Rocket Team
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Hi Zach: I think there are a lot of great projects to be done with that idea. Take a look at http://www.corriewolfe.com/spacewifi/ for example. The students used a FingerTip3 Linux card with a CompactFlash WiFi card to make a secure tactical data network relay. They also put a GPS receiver onto the package so that it could be tracked.     Best wishes,     Will
Zach wrote:

--
Will Marchant, NAR 13356, Tripoli 10125 L3
snipped-for-privacy@amsat.org http://www.spaceflightsoftware.com/will /
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These data radios work well for rocket borne telmetry.
http://www.maxstream.net /
I just don't like all the other overhead with ethernet.
small light weight Pic based devices then work easier with the com based devices.
a single board PC with those ethernet bridge would work well.
It just seems like extra weight to me, but does have the advantage of not needing custom embedded like development tools or knowledge.
CD
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I've had good luck with similar units from Aerocomm. Essentially wire replacements - serial data in on one end, serial data out on the other. The radios take care of the protocol. I use an AVR processor to decode and display the GPS coordinates on a LCD and send them to a laptop for mapping with ExpertGPS. I want to add data logging capability so I can record without the laptop and then playback later.
Cranny Dane wrote:

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jdMARS wrote:

only 1km range - maybe not enough?
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Thats with the dinky stub antennas built in. That 1km range is horizontal along the ground, going up will get you more. Add a yagi antenna on the ground and 2-3km should be easy.
But its a guess until someone tests one.
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We'll be flying one at NYPOWER this year.
Doug Pratt www.pratthobbies.com
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I use wireless ethernet for configuring my Windows 98 computer. http://www.geocities.com/rdh82000/L3/Flightcomputer.htm
Flown 5 or 6 times. First flown 3-4 years ago. I need to update the page as it has a better power supply that allows a ground based umbilical power. Also replaced the FM Tx with a FRS radio. Added the ethernet and use VNC to talk to the computer on the ground but have had flights with full reception. Also added the GPS.
I hope to revamp the software and fly it again at LDRS this year in a two stage rocket. Boosted by 3 x M1900BB staging to a 98mm 10,000 motor probably BB.
Robert DeHate Animal Motor Works, Inc.

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