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Long range light weight radio modem for a small UAV

Discussion in 'Embedded' started by Guest, Dec 20, 2005.

  1. Guest

    Guest Guest

    Can I ask some expert advice to select radio modems to be used in a small
    UAV (a model airplane infact) ?
    Desired specs for the radio modem;
    o Range : 5km (or more)
    o Weight : Lighter than 150gm
    o Data rate: 56-115.2K bits/sec
    o Interface : RS232 (and/or TTL)
    o Price : Must satisfy budget constraints of five uni students (ie. as
    low cost as possible) :(
     
    Guest, Dec 20, 2005
    #1
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  2. Guest

    karel Guest

    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!
     
    karel, Dec 20, 2005
    #2
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  3. Guest

    M. Noone Guest

    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. Noone
     
    M. Noone, Dec 20, 2005
    #3
  4. 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
     
    Mark Borgerson, Dec 20, 2005
    #4
  5. Guest

    Richard Guest


    Think we have been here before. See:
    http://groups.google.com/group/aus....m+radius+radio+modem"&rnum=1#36491f7d43e2dc30

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

    Regards,
    Richard

    http://www.FreeRTOS.org
     
    Richard, Dec 20, 2005
    #5
  6. Guest

    pbreed Guest

    try www.maxstream.net

    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
     
    pbreed, Dec 20, 2005
    #6
  7. 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
     
    Paul Keinanen, Dec 29, 2005
    #7
  8. I recently did buy some radiometrix module transceivers 64kbs half duplex
    for 20?
     
    Sagaert Johan, Dec 29, 2005
    #8
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