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fm receiver

Discussion in 'Electronic Basics' started by [email protected], Jan 3, 2007.

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  1. Guest

    iwant to make a fm receiver to receive signals at 145MHz
    can any one help me with some ideas
     
  2. Tom Biasi

    Tom Biasi Guest

    What do you want to receive?
    Satellite downlinks, Ham, Repeaters?
    How sensitive does the receiver need to be?
    Tell more story.

    Tom
     
  3. Guest

    well its for a competition where i have to dectect the origin of signal
    kept in a range of 1 km sq
    as i a begginer i really need help
     
  4. Guest

  5. Tom Biasi

    Tom Biasi Guest

    You might check with Ham Radio Clubs in your area; they often do 'Hidden
    Transmitter' games.
    You could also check ARRL for radio direction finding.

    Tom
     
  6. S.Ramamurthy

    S.Ramamurthy Guest

     
  7. S.Ramamurthy

    S.Ramamurthy Guest

    consult
    Calicut Radio Society

    VU2CME
    Amateur Radio and Electronics Club,
    Calicut Medical College,
    Calicut-673008.

    regards,
    S.Ramamurthy
     
  8. Don Bowey

    Don Bowey Guest

    Google
     
  9. Guest







    FM freqency band range is 88 MHz - 108MHz. How it is possible?
     
  10. Because "FM" has sloppily become the term for the FM broadcast band,
    88 to 108MHz in North America and sometimes a slightly different range
    in other parts of the world.

    But "FM" means Frequency Modulation, and it's a form of modulation that
    has nothing to do with the frequency of the transmitter. "FM" varies
    the frequency of the transmitter according to the modulating signal sent
    to it, as opposed to "AM" (which also sloppily gets used to mean the AM
    Broadcast Band, 540KHz to 1710KHz, or thereabouts), where the modulating
    signal is translated to radio frequency, and part of the output signal
    directly reflects the amplitude and frequency of the modulating signal.

    So anywhere that one is allowed to use Frequency Modulation, it can
    be used.

    Michael
     
  11. Don Bowey

    Don Bowey Guest

    Use Google. Do you not understand this simple suggestion for finding your
    answers?
     
  12. me

    me Guest

    or break down and read a book (gasp!!)
     
  13. That's just the FM broadcast band. You can frequency-modulate any
    EM wave. Narrow-band FM at VHF and UHF is widely used by everyone
    from hams to NASA.
     
  14. Rich Grise

    Rich Grise Guest

    Yeah - NASA uses NBFM. Why? When they can send down broadcast-quality
    video, why can't they get audio any better than the "Order Here" box
    at quik-e-burger?

    Thanks,
    Rich
     
  15. Bob Myers

    Bob Myers Guest

    At least for Shuttle orbiter communications, it's not NBFM - it's a
    digital PM system, which allocates only about 24-32 kbits/sec to
    the voice channels. See:

    http://science.ksc.nasa.gov/shuttle/technology/sts-newsref/sts-ovcomm.html

    I would imagine that the "broadcast-quality video" transmissions are
    actually very seldom used; they'd be huge BW hogs, and likely mean
    that other data transmissions (telemetry, etc.) have to be suspended
    while the video transmission is going on. (If you want to put it in more
    cynical terms, the "live video" transmissions are for the most part for
    PR purposes - to give the broadcast media something to show the
    Ammurican Taxpayers on the evening news. They set everything else
    aside, send a few minutes of nice footage, and then get back to
    business.)

    The quality level of the voice transmission was no doubt chosen to
    be adequate for the purpose, while not taking away too much of
    the channel capacity from other purposes.


    Bob M.
     
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