Remote control – 2: Sample your remote
== 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).