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I am looking for a module that would be able to receive communication in the 433.42 (ch01) range with ASK/OOK modulation. Can someone recommend anything that would work and not be an expensive general purpose SDR module?

Long story: I have tried using the cheap RF 433MHz modules(picture below). I was able to modify the transmitter by de-soldering 433.92 crystal & soldering-in 433.42 one (picture two).

Now I have no way of testing this, as I am not receiving any communication while using the standard receiver that is tuned to 433.92 MHz. There doesn't seem to be any obvious way to tune the receiver to 433.42 MHz.

Reference ebay example for the crystal oscillator.

433.92 transmitter & receiver modules 433.42 crystal

kubal5003
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  • I was able to solder the crystal ... solder where? ... are you sure that it is a crystal? – jsotola Feb 16 '24 at 21:53
  • please add a reference to the pictures into your post ... edit the post, do not write a comment – jsotola Feb 16 '24 at 23:50
  • This is quite a good description of those modules and how to use them https://lastminuteengineers.com/433mhz-rf-wireless-arduino-tutorial/. If the receiver is no longer tuned to your modified transmitter, then you could try adjusting its [the receiver's] trimmer (brass coloured screw in the green cube). – 6v6gt Feb 19 '24 at 07:47

1 Answers1

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It turns out that:

  • the receiver DOES work with the different frequency when the range is sufficiently small (a couple centimetres at most)
  • the library that I was using was expecting different kinds of transmissions so it wasn't showing anything useful
  • only low level interrupt service routine is actually giving me access to the actual data from the module
  • the issue that is complicating things with those modules is that in the absence of actual transmission noise is getting amplified and the module is outputting gibberish, so serious thinking needs to go into recognising when actual transmission starts & ends
kubal5003
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