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'Long distance' IR remote control learning.

Discussion in 'Electronic Repair' started by N Cook, Aug 22, 2006.

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  1. N Cook

    N Cook Guest

    That is going across continents.
    To transfer the pulse coding of a remote control at one site to another
    learnable type remote control maybe the other side of the world.
    Can anyone think of a method that uses off the shelf equipment used in a
    domestic environment , ie not using oscilloscopes etc.
    Somehow slowing the pulse stream down enough to capture on cam-corder/pc
    etc.
    Would the average r/c with say a 400 KHz ceramic resonator still function
    with the 400KHz one replaced with 100KHz one say.?
     
  2. Look up LIRC (linux infrared remote control).

    For example, I can type remotecontrol.p (a PERL program) on any computer
    on my network, and the satellite receiver downstairs changes channels.
    I can also control a VCR and Stereo Recevier.

    If the remote control you want to duplicate is not listed, you need
    to use a receiver to decipher the codes. You can make one yourself or
    buy one for about $30.

    The remote transmitter can be as simple as an IR LED and a resistor. Since
    my equipment faces a window, instead of trying to make a unit bright enough
    to overcome the sunlight streaming in, I just made three of them connected
    to the same serial port and placed an LED next to each sensor.

    The remote computer does not have to be much, it needs to run Linux,
    have some sort of network connection and a serial port.

    Geoff.
     
  3. jasen

    jasen Guest

    there's a open remote project on sourceforge, i'm not siure what they use to
    record, I think either IRDA or some cheap hardware.
    probably.

    the pulse rate is ~40Khz most PCs can handle that.
     
  4. N Cook

    N Cook Guest

    I don't own a web-cam but anyone know what would happen if
    you replaced the IR LED with a diffused red LED and shone it close to a web
    cam.
    Starting with a normal IR R/C with its original crystal and normal pulsed
    output of 25uS per pulse and 20 pulses per bit of data. Would that produce a
    resolvable video stream that could be sent via internet and assuming a wide
    enough acceptance spectrum of the receiving phototransistor/diode of a
    learner type universal r/c straight off a pc monitor in a dark room.
     
  5. Tim Auton

    Tim Auton Guest

    Webcams can usually see near-IR reasonably well anayway.
    No. Webcams can manage perhaps 30fps. You'd need something much, much
    faster.


    Tim
     
  6. I did that in the 1980's with an IR photodiode, an LM324 op amp and an
    IR LED. Another thing I should of patented.

    Geoff.
     
  7. Chris Jones

    Chris Jones Guest

    An old PC (even a 386) running only a DOS application with all the
    interrupts turned off can sample the printer port to memory at maybe 1MHz
    and could probably do your task if you attach a photodiode and comparator
    of some sort, with a reasonable frequency response, or cheat and open the
    remote to get the logic signal out directly. Given sufficient
    determination, this might also be achievable with a modern computer running
    some sort of windows too, at least in theory. Since the modulation is only
    about 40kHz on most remotes, you might be able to find some sound card with
    Audiophool grade sample rates like 192kHz, which might also work, with a
    suitable photodiode or connection to the LED. As you suggest, slowing down
    the clock of the remote would make things easier, and I think it would
    work. You could then use a tape recorder, sound card or whatever
    non-compressed audio recording device you want. If you slow it down too
    much then you might want to put some current limiting in the LED as they
    run them above the continuous current rating, and at a sufficiently low
    clock rate the LED may burn out.

    I think it might be hard to use a VCR and photodiode to record the signal
    because having sync pulses might prevent you from capturing enough
    continuous signal from the remote. If you can get a VCR to record without
    h-sync pulses being present then it would certainly be a very high
    bandwidth recording device.

    All of the above sounds like more work than putting the learning remote in a
    box and posting it to the required location. Why are you interested in
    this problem?

    Chris
     
  8. jasen

    jasen Guest

    I don't think web cams record an analog video stream...
    and if they did the compression would mangle it beyond recognition.
    webcam video uses a much lower frame rate than pc monitors use...
     
  9. N Cook

    N Cook Guest

    Thinking of worthy patentable devices
    I wonder if anyone makes this sort of truly unirversal r/c for those
    annoying situations of one or more key functions missing from the one you
    want.

    2 stages
    1/ Just the recognition code going through all possible permutations
    to find the basic power on/off repeated sequence.
    Lock that down in memory
    2/ and then after that specific code, all operational bit sequences until
    that does a function on the TV etc and lock that to a button on the r/c.
     
  10. Grumps

    Grumps Guest

    Maybe not a solution in your situation, but Logitech Harmony remotes might
    suffice. You can 'teach' a device that you have in one location, and the
    same device can be uploaded (via the interwebnet thingy) in another
    location.
     
  11. webpa

    webpa Guest

    Maybe I'm missing something important about the problem, but I use a
    program called OmniRemote Pro....which is designed for Palm OS
    hand-helds. Basically, it turns any Palm OS PDA with IR (all, as far as
    I know) into a programmable, "learning," IR remote control. There are
    many, many other software solutions that do the same thing for other
    OSs (WinCE, Linux, Mac) and other hardware. There are also, on-line,
    several databases of IR pulse codes for many consumer devices...from TV
    receivers to air conditioners.
     
  12. jasen

    jasen Guest

    you would die waiting if it went through all possible codes.
    that bit is somewhat easier... once the baudrate, carrier frequency,
    and encoding scheme are known all that remains is to experiment with
    hundereds of possible symbols.

    Bye.
    Jasen
     
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