remote decoder.

Discussion in 'The Projects Forum' started by lesin akbar, Mar 14, 2008.

  1. lesin akbar

    Thread Starter Active Member

    Dec 16, 2007
    30
    0
    I need to built a device which can detect the frequency coming to it. I shall make it more clearer, ie the remote controlled device i need to built should have a global transmitter, ie i should be able to assign any transmitter for my device. I may even use my TV remote. So for this thing first i need to detect the signal and save it, now whenever the same frequency is found the ckt is activated. So i need to know how am i going to identify that signal.(i know the programing of mc's). Hope the idea is clear. plz help
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    What you have in mind sounds a bit like a panoramic receiver. It would help if you could narrow the range of frequencies down a bit - modern RF bands cover all the way from 7 Hz up to over 10 GHz. One receiver can only cover a limited range of frequencies.
     
  3. lesin akbar

    Thread Starter Active Member

    Dec 16, 2007
    30
    0
    Thanx for your fast response. But I only need to decode the IR signals and i think the standard is 38.5 KHz. (eg. TV remote). Now only thing is that i just have to catch a signal, and whenever the same one comes again i need to identify it. Never interested in the data and all, i need only to identify the pattern.
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
    282
    Well, any old phototransistor will see the IR. While the IR turns on and off at around 38 KHZ (don't know how I got onto RF), the control codes are pretty much patterns of variable on and off periods. If you look at a remote with a digital camera, you can see the IR transmitter wink on and off.

    As far as recording the pattern and recognizing it later goes, it sounds like a job for a microprocessor and a certain amount of memory for storing/searching those patterns.
     
  5. Spoggles

    Well-Known Member

    Dec 2, 2005
    67
    0
    Check out the picaxe 08M..

    Spoggles
     
  6. Søren

    Senior Member

    Sep 2, 2006
    472
    28
    Hi,

    Carrier waves for IR-remotes (TV, HiFi or whatever) can be anything from around 25 kHz to 455 kHz.

    (K = Kelvin, k = kilo).

    The pattern IS the data!

    Take a look at this page about IR-remotes to learn the difference between the carrier and the data (and then some).
     
  7. lesin akbar

    Thread Starter Active Member

    Dec 16, 2007
    30
    0
    thank you all for ur valuable responses. I know how to work with micro controllers(AT89C51), so thats not going to be a problem, i hope so. I more doubt , when we press (and hold it like that) a key of a RC of a TV will the pattern be generated periodically , continuously or will it be coming only once ?
     
  8. lesin akbar

    Thread Starter Active Member

    Dec 16, 2007
    30
    0
    Oops, sorry, i didnt checked the links you've(soren) given. Ive got everything what i need. Thank you again. and thanx for directing me to such a cute chip picaxe 08M.
     
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