For my school project, my objective, among others, is to detect EMF changes (frequencies between ~400MHz and 2,4GHz) in a room (to simplify it even more, let's assume it's gonna be very small room/space, for example anechoic chamber), so RF transmissions, mobile phones (GSM & LTE) and wifi. What's important, I do not want to connect with any of the devices, nor capture their signal, just detect their presence. I found this (it's build on Arduino, but should be rather easy to adapt it for RPi), but not sure about it and looking for alternatives. I'm not interested in measuring power of the signal, not in the first place, but if there would be something serving also this purpose, it would be appreciated.

2 Answers 2


You might also consider a Software Defined Radio (SDR). The hardware is usually a cheap USB device which plugs into a computer or Raspberry Pi. You can find a tutorial for how to use it with a Raspberry Pi by googling "Raspberry Pi RTL-SDR Scanner" but that is outside the scope of the question.


The EMF detector in your link will not work for you for two reasons:

  • RPi doesn't have any ADC pins (needed for the analogRead() function)
  • It will be limited to to very low frequencies, nowhere near 400MHz

An SDR dongle (basically an FM/TV tuner which gives you access to raw signals) is something to look at. You can also find reasonably-priced spectrum analysers nowadays too.

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