Remote control – 2: Sample your remote
Pubblicato da jumpjack su 22 Maggio 2008
== 2 == SAMPLE YOUR REMOTE
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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Mike detto
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 detto
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…
Mike detto
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?
oopsyourhead detto
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 detto
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)
Andrew G detto
Is there a place where I can get an IR recording that works for sure so i can troubleshoot my emmitter?
jumpjack detto
What do you mean? Aren’t you able to sample your remote using an IR LED connected to microphone input?
Andrew G detto
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.
Andrew G detto
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 detto
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 detto
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.
Pablo detto
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?
Thanks!
jumpjack detto
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.
jumpjack detto
send me your file at jumpjack at libero dot it, I’ll check it for you.
Which device are you attempting to control?