Long range light weight radio modem for a small UAV

schreef in bericht news:43a80b79$0$18197$ snipped-for-privacy@news.optusnet.com.au...

I am not an expert on the matter, but have some teaching on aviation and the use of radio comm's therein.

have you any idea of the preferred carrier frequency? VHF (80-150 or so MHz) offers good reliability but is line of sight, i.e .will not follow the earth's curvature

at a very rough estimate, 5 kms range would require 400 ft flying altitude - dos that sound reasonable?

though I have received tower comm's at /- 10 kms distance quite clearly, with a simple receiver, and neither tranmitter nor receiver applying high antenna structures

final tip: i remember seeing some projects of R/C aircraft with a camera and transmitter installed so as to monitor the camera image on the ground let google be your friend!

Have a look at sparkfun.com - they have some nice cellular modules that look like they might work pretty well for you. They also have two lower speed rf modules, um96 and um12, that have very good range (which will improve very much when in the air). Best of luck,

M. No> Can I ask some expert advice to select radio modems to be used in a small

The 9Xtend series from MaxStream may fit your requirements. The modules are about $299. ( you wil need 2, of course). I'm in the early stages of evaluating a system that uses these modems, so I can't tell you much about their ease of use and reliability.

Mark Borgerson

Think we have been here before. See:

Unfortunately the top of the thread contains some childish crap, but later some info.

Regards, Richard

try

I've personally tested their Xtend modules to more than 75 miles.

Standard Dipole on the airborne end, a small dish on the ground.

Test was terminated at 75 miles because that was as far as we needed and I could not legally climb any higher, without oxygen, to maintain a clear line of sigt over a mountain ridge where we were testing.

I've tested their raidos to over 20 miles with dipoles on both ends and no gain.

These tests seem to be somewahat sensitive to the population density in the area,

7 miles was my max measured range on the ground in the San Diego area.

Be aware that they are line of sight and you must respect the freznel (spelling?) zone limits.

Paul

I really hope that you do not intend to send the flight control commands over any toy radio modem operating in a license free band. Such links are vulnerable to interference from other users on the band and these radio modems usually operate in half duplex, with unpredictable latencies.

I would suggest using a separate R/C command system for flying the plane that operates in a band dedicated for R/C activities and use a separate radio modem for telemetry downlink. In this way the links can operate independently in full duplex mode.

When selecting the downlink radio modem, you should also check if it is allowed to use airborne transmitters in a license free band (such as 2,45 GHz).

Paul

I recently did buy some radiometrix module transceivers 64kbs half duplex for 20?