Jumping Jack Flash weblog

Remote control – 2: Sample your remote

Posted in hardware, Infrarossi by jumpjack on 22 maggio 2008


a – Start “Audacity”

b – Plug your receiver into MICROPHONE input of your sound card

c – Place your remote in front of the LEDs

d – Start recording: stereo track, 7600044100 Hz, 16 or 32 bit.

e – Press a button on remote

f – Stop recording

Ok, now you have a sample of one button of the remote. You should see two different tracks: you’ll have to consider just the one which looks like a “square wave”.

Indeed, on my audio card (VIA AC’97) sampling on one channel results in a sequence “triangles”, while on the other channel I get a sequence of “rectangles”. You’ll have to ZOOM a lot into the waveform, both vertically and horizontally, as the signal is very short (few milliseconds), and probably quite low.

The meaning of squares is “digital”: if the signal is high, it means a 38 KHz carrier is present; if the signal is low, no carrier is transmitted. Remote controls use different protocols to tramsmt signals. Look at this page for details (but you don’t need to know details to complete your remote transceiver).


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63 Risposte

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  1. […] (RSS) « Remote control – 2: Sample your remote Remote control 4: the emitter […]

  2. […] (RSS) « Appunti su fattibilità telecomando tramite cellulare Remote control – 2: Sample your remote […]

    • mifkey said, on 15 ottobre 2014 at 0:40

      Hi,mr.Jumpjak…h r u…I m a projectl lover recently saw ur this amaizing ir clone device…its working man…I m very exciting now what ever I see ir device I try…recently ir-heli 3channel is underway if I found any problem I’ll contact u….thanks again I tried on settlit rx,vcr.

      • mifkey said, on 15 ottobre 2014 at 10:21

        Hi,jumping jack,,,,regarding ir signal cloning,,,I got another successs as I wrote before that current project is under way…rc heli 3 channel,I successfully startup the heli through Audacity and all ir prosedures but I found new things….I’ll discusss you in the next post…by then
        Good Buye….Take care

  3. Mike said, on 22 febbraio 2009 at 5:23

    on Audacity when i record a “button” i get 2 chaneles with the same squair waves. i dont get the second triangle wave. please help…

    • jumpjack said, on 22 febbraio 2009 at 9:17

      I didn’t understand correctly, could you send a screenshot?
      Anyway, you must sample in MONO, not in STEREO.
      And you don’t need triangle wav but square waves, discard the triangles…

  4. Mike said, on 22 febbraio 2009 at 18:31

    i think i got the recording down.
    i am not sure how to add pictures to this fourm but you can email me and i will reply with a few pics or maby if you can i can send you download links to the raw files and maby you can do it for me?

  5. oopsyourhead said, on 31 marzo 2009 at 2:45

    I’m having trouble doing this, I built the receiver and have tried getting the commands, but all I get is static, no square waves or anything from left or right, i’ve tried mono and stereo with the settings posted here, but I have no clue what’s messing up

    • jumpjack said, on 31 marzo 2009 at 17:42

      There are so many things which can be gone wrong…
      Can you post/upload/send pictures of the receiver you built?
      Are you using a proper LED? (It must be infrared, not “standard” LED)
      Is remote control close enough to the receiver? (no more than 10 cm/ 4 inches)
      Are wires properly connected? (try touching them with your fingers while recording: this should be in “something” being recorded, if wires ARE connected to soundcard.
      Is recording from microphone enabled? (double click on speacker icon in traybar to open sound control-panel and enable microphone)

  6. Andrew G said, on 2 ottobre 2009 at 3:00

    Is there a place where I can get an IR recording that works for sure so i can troubleshoot my emmitter?

    • jumpjack said, on 2 ottobre 2009 at 8:47

      What do you mean? Aren’t you able to sample your remote using an IR LED connected to microphone input?

      • Andrew G said, on 2 ottobre 2009 at 20:59

        Yes but unfourtantly i don’t think i’m doing it right. If i had a .wav file that works for sure then i could do a digital camera test to see if i’m recording and editing wrong or building the emitter wrong.

        • jumpjack said, on 3 ottobre 2009 at 11:48

          send me your file at jumpjack at libero dot it, I’ll check it for you.
          Which device are you attempting to control?

  7. Andrew G said, on 4 ottobre 2009 at 23:15

    I’m testing this on my Sony VCR but i want to control my Time Warner HD Cable box when i get this to work. I sent you an email.

    • jumpjack said, on 5 ottobre 2009 at 9:26

      File you sent me lasts more than a minute against some milliseconds it should last. Maybe my raw2lirc and lirc2ledrem programs got confused for some reasons by your sampled wav file.
      Please send me your original sample.

      • Andrew G said, on 5 ottobre 2009 at 23:40

        Thank you so much for your help! I did not notice your email when I sent my *.wav to you. That is why I also sent an audacity project file with it.

  8. Pablo said, on 13 ottobre 2009 at 23:56

    Hi!, i am able to record my signal, however, the signal is inverted compared to the graph above. Is this the same or i have to invert it to match the screenshot?

    • jumpjack said, on 14 ottobre 2009 at 9:26

      You can invert the led to get a proper signal, or you have to silence the 19000 Hz tone when the signal is UP rather than down.

      To be sure if the LED is properly connected, look at the signal level when you are NOT pressing any button: that is the 0 level; as soon as you press the button, you must see the signal RAISING to “1” level; if instead it’s going down, you need to invert your LED.

  9. JMSiefer said, on 14 novembre 2010 at 10:17

    Excellent set of articles!!!

    I was wondering if you might be able to help me out with something. I’m looking to directly connect the IR LED leads on the transmitter, to the circuit board that has the IR receiver. I want to do this so that instead of communicating using infrared light, I would have a wire connected directly from my computer’s speaker port to my toy car- sending signals straight to it.

    Here are some pictures of what I have:

    In picture 1, I have the opened up IR transmitter with the IR LED still connected.

    In picture 2, I have the IR Receiver (sensor), which has 3 pins, and which I’m not sure what each is for.

    Then in picture 3, I have the IR Receiver (sensor) above the circuit board of where the connections are supposed to join (though I clipped them off).

    Please let me know how I could get this to work. My end goal then is to play the IR audio files directly from my computer, which would run via a wire straight to my toy car, and which could then control it.

    Thank you so much in advance!!! I appreciate any help that you could provide me with.

    • jumpjack said, on 14 novembre 2010 at 13:37

      I’m sorry but I don’t thin it is possible: your receiver has 3 leads rather than two: this means it’s not just an IR receiving diode, it also includes some circuitry which decodes recevied IR singnals into something the RC car circuitry can understand; in other words, no “waveforms” comes out from the 3 leads, but rather some digital signals, totally different from waveform you transmitted to it.

  10. Abhilash said, on 26 maggio 2011 at 18:33

    Hi,thanks for posting the article.
    I am able to record the signal, but the signal appears sinusoidal on one channel and a series of spikes on the other.Please let me know which of the two signals I’ve to use.
    Thanks in advance.

    • jumpjack said, on 26 maggio 2011 at 20:12

      just the sinusoidal one, discard the “spikes” one.

      • Abhilash said, on 27 maggio 2011 at 10:18

        Thanks for the reply.

        could you please point to the waveform you are referring to?

        Audacity recording

        Magnified ver:
        Audacity Recording

        I followed the procedure further and generated a .WAV file but unfortunately its not working.

        • jumpjack said, on 27 maggio 2011 at 12:14

          Second track looks good; other track shows just interference of one wire on the other.

      • Abhilash said, on 29 maggio 2011 at 9:49

        Thanks for looking through.

  11. dani arnaout (@dani_arnaout) said, on 3 novembre 2011 at 18:31

    hi , i’ve built the receiver , connected it, started recording. Then pointed the remote control and got some sort of signal.
    After Zooooming in , i found only triangular waves that looks like this.. i’ve tried another remote and still the same results.

    • jumpjack said, on 3 novembre 2011 at 20:33

      I think you’re recording the wrong channel or keeping the remote too far from the receiver (they must be just a few centimeters apart).

    • dani arnaout (@dani_arnaout) said, on 4 novembre 2011 at 12:51

      the remote is only 1 or 2 centimeters apart. so concerning the wrong channel , how can it be resolved? i’m recording on Mono 32-bits 44100Hz :/

      • jumpjack said, on 4 novembre 2011 at 13:20

        you have see 3 wires in your receiver, and you used only 2 of them.
        Wires are GND, Left and Right. If you sampled over GND+Lef, try GND+Right.

        In my picture, GND is in the center, Left and Right are up and down:

        You connected just two of them, try the missing one:

  12. Arthur said, on 5 febbraio 2012 at 16:13

    Hi, I saw the LED light on, does it means that my detector works?

    however, i see no wave pattern in my audacity recording.

    • jumpjack said, on 5 febbraio 2012 at 18:42

      You should see the LED on in the EMITTER, not in the receiver!
      What did you do exactly?

  13. TC (@bzikofski) said, on 31 luglio 2012 at 19:13


    I’ve built the same thing to control my NEX camera but I can’t get it to work.

    How can I troubleshoot this?
    1. LEDs I used: http://www.maplin.co.uk/ld271-infrared-emitter-2262
    2. Cable works (I tested it)

    Please help! 🙂

    • TC (@bzikofski) said, on 31 luglio 2012 at 19:49

      Also, while reading other comments here – it looks like I CAN “sample” the existing remote using microphone input on my computer – it shows me the signal when I press button on the remote..

      • jumpjack said, on 6 agosto 2012 at 11:22

        Please send me both one recorded signal and corresponding synthesized signal (.wav files).

  14. […] Remote control – 2: Sample your remote […]

  15. Ravi Aryan said, on 31 luglio 2013 at 17:54

    Plz confirm sampling 76000Hz or 44100Hz …as i am failed after doing same steps as you given here.

    i used 44100Hz, 32 bit…. but my .wav file not working.

    • jumpjack said, on 1 agosto 2013 at 10:24

      Use 44100.
      Please send me your original and your generated .WAV and I’ll take a look.

  16. Ravi Aryan said, on 1 agosto 2013 at 13:24

    please give me your email id……..

  17. Ravi Aryan said, on 2 agosto 2013 at 13:25

    Thank you very much for such a wonderful tutorial and your support……I appreciate all of your hard work and effort.

  18. Johne5 said, on 9 agosto 2014 at 16:59

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    • jumpjack said, on 11 agosto 2014 at 8:43

      Yes: find a girlfriend and stop spamming.

  19. musiconly said, on 7 febbraio 2015 at 15:48

    I know it’s a bit old post, but since it’s still relevant, I’d like to ask you for your help 🙂

    I can’t get square signal, and I don’t know what I am doing wrong. My signal always looks like this http://i.imgur.com/dLdqSWQ.jpg

    I tried recording both mono and stereo, 44100Hz, 32 or 16 bit and it always looks like this.

    I tried with 2 IR Led’s I got from old remote controllers, cable is 3.5mm extension cable male to female: https://sewelldirect.com/images//products/SW-8325/SW-8325.jpg

    Cable has 3 wires, red, white, yellow. I assumed red is right, yellow is left and white is ground. I connected + on red wire, and – on white wire. I tried using yellow instead of red and it doesn’t produce any signals.

    I even put new batteries in my remote controller and distance from controller and my IR receiver is less than 1 cm.

    TV is Phillips, and I’m trying to capture power button.

    Any thoughts?

    Thanks in advance 🙂

    • jumpjack said, on 7 febbraio 2015 at 18:25

      I think you are using the wrong wires! The signal is there… but it’s so weak that I think it’s just magnetic induction for the OTHER wire. Try all combinations of the 3 wires: A+B, B+C, A+C.
      Additionally, to record you need just ONE led, not two.
      You can also try looking for “discrete power on command” for your TV set on http://www.remotecentral.com

      • musiconly said, on 8 febbraio 2015 at 13:52

        We’re getting there 🙂 I switched wires and got this signal:

        Then I used plugin for Audacity from samygo IR Converter, that automatizes your 3rd step of this tutorial. I found plugin here:http://forum.samygo.tv/viewtopic.php?f=21&t=7689&p=59081#p59072

        With that plugin i got this signal:

        Do they look good to you?

        As I can see, signals are inverted and it all looks promising, but…

        When I built emitter, and play the sound from audacity, TV doesn’t respond.
        I placed my emitter 1cm in front of TV receiver.

        My emitter is connected like you described on the last step of this tutorial.

        As for the discrete power on command, I’m currently trying to record only power button, but I need 4 more buttons recorded, so I don’t think discrete power on command will help me.

        Thank you jumpjack!

        • jumpjack said, on 8 febbraio 2015 at 20:06

          I think your signal lacks the initial parts (a long “high” signal).

          Try considering the 4th or 5th burst rather than first one, to give the signal the needed time to get stable.

        • jumpjack said, on 8 febbraio 2015 at 20:11

          Anyway your batteries do not look that good, signal appear not able to stay high for so much time in your sample.

  20. musiconly said, on 9 febbraio 2015 at 11:57

    Thanks again for helping me. I really appreciate it.
    I took a remote from a brand new TV (LG), fresh batteries inside. Here’s what I got:
    This is like the 7th signal burst.
    I even changed cable, I took an old headset instead of that extension 3.5mm cable I was using.
    I can’t seem to capture on my smartphone camera a violet ligth from my emitter. I see it very bright coming from my TV remote, but not a single flash of infrared light from my emitter.
    I connected it like this:
    Where red wires coming from lego brick are -, yellow ones +.
    Is it possible that there is something wrong with LEDs? They can capture the signal, but not emit?

    • jumpjack said, on 9 febbraio 2015 at 15:27

      Your sample still looks wrong, try encoding this signal instead:

      • musiconly said, on 10 febbraio 2015 at 13:01

        Thank you soo much, you were very helpful! 🙂 I don’t know why I kept getting weak signals, but manual editing like you showed me in your last comment is working.

        • jumpjack said, on 10 febbraio 2015 at 13:44

          Very good!

        • jumpjack said, on 10 febbraio 2015 at 13:48

          It would be also interesting to check if modern smartphones and PCs are capable of playing a raw 38KHz wave and thus controlling devices using one single led.
          I didn’t test tansmission, but my PC can sample at frequency high enough to see the 38 kHz carrier.

          • musiconly said, on 11 febbraio 2015 at 12:43

            I just tested emitter with one single led and it’s working on my PC. I haven’t tried it on smartphone.
            On a side note, playing signal in Audacity works, VLC and Windows Media Player don’t work, Windows8 app “Music” is working, and Chrome play wav perfectly, so now you can control your TV through a website (HTML5 audio player with wav as source).

  21. Wor said, on 21 giugno 2015 at 10:25

    Hi there I cannot get the right square signal

    i already change the wires

  22. Madara said, on 25 giugno 2015 at 18:56

    Hello, can you please help me.. I`m not able to get the signal..!!

  23. Pavle said, on 6 febbraio 2016 at 23:06

    You can use android as remote if you make IR remote and download Zaza remote app from play store.
    IR remote: http://www.instructables.com/id/DIY-Infrared-transmitter-for-iPhone-iPod/

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