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RF modules with encoding?

Discussion in 'Electronic Design' started by Tony Williams, Jun 29, 2007.

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  1. I used modules from <http://www.rfsolutions.co.uk> Speff.
    From Farnell, or Newark in the US.
     
  2. Hi, all:-

    I'm looking for a small, and low power, pair of RF modules (send and
    receive, only one-way communication) that could be used to send a
    couple of messages (specifically, "ON" and "OFF" commands) with
    encoding so that stray RF won't cause it to malfunction (the
    consquences are expensive, and possibly even dangerous). Maybe
    something in the ISM band. If the transmitter works off a key fob with
    a button cell, all the better. It would be nice if there was no local
    oscillator or other leakage of signals from the receiver. There will
    probably be a number of receivers and a single transmitter. Range is
    not an issue (a few dozen meters is fine).

    It doesn't have to be really secure against deliberate attempts to
    spoof the code, just against accidental actuation.

    Any suggestions?


    Best regards,
    Spehro Pefhany
     
  3. Joerg

    Joerg Guest

    Check out the X-10 key fobs. Really cheap. Their receivers are IMHO not
    very good so you'll have to roll your own.
     
  4. Gary Tait

    Gary Tait Guest

    I have heard of some (like Holtek perhaps), although they do no more
    than gate the carrier on and off based on the logic you feed them, and
    present a signal at the receiver based on the status of that logic
    signal entering the trasnmitter. Error correction and that would be don
    by the logic you supply on either side. That said, you could use simple
    remote control transmitter chips or a micro in the trasnmitter, and a
    micro to decode, if no direct decoder IC is available..
     
  5. Thanks, Tony, they look decent.

    Best regards,


    Best regards,
    Spehro Pefhany
     
  6. GPG

    GPG Guest

    http://www.linxtechnologies.com/
     
  7. Tesseract

    Tesseract Guest

    I second the recommendation for Linx Technologies. You can get Holtek-encoded
    keyfob transmitters with 1 to 5 buttons off the shelf and pair them with
    their KH2 receiver/decoder modules for very cheap and Digi-Key stocks them.
    Be aware, though, that Linx requires you purchase one of their evaluation
    kits before they will sell to you direct anything not already FCC approved
    (ie - you can buy the keyfobs but not the matching receivers without first
    buying a stupid ev kit).

    -Jeff
     
  8. Fred Bloggs

    Fred Bloggs Guest

    ... Range is
    Don't you have to stand back farther than that? Or is the operator
    expendable...
     
  9. speff

    speff Guest

    It's almost the reverse situation of what you are thinking...
     
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