Hey to you all.
I need help in this: The beacon emits infrared radiation with a wavelength of 940nm. This signal is modulated using 600 Hz on-off keying over a carrier of 40kHz. The “dutycycle” of the modulating signal (600 Hz) is 30%.
I only need to detect the presence of this signal using a PIC microcontroller. Don’t need to decode anything. My led uses a 38kHz carrier frequency. Can I still use it to detect the presence of the IR signal?
Thanks in advance.
yes, but according to the datasheet, Fig. 5, you will lose about 25-30% sensitivity.
After some tests I’ve observed that the LED saturates after some (little) time… There is an easy way to stop that from happening?
what do you mean by "saturates"? And how little is "little time"?OxyGenDiogo:
After some tests I’ve observed that the LED saturates after some (little) time… There is an easy way to stop that from happening?
I mean that after 5ms for the emitter close to the led and about 5 seconds a few meters away the led stops giving correct values… I turn the power off, wait a few seconds, and it works fine again.
ok getting closer…
I assume that by °correct value° you mean a 600Hz, 30% duty signal. What do you see instead?
BTW that is not a LED at the receiving end, it’s a PIN plus preamp.
Can you post the receiving circuit?