General Question about processing cellular phone signals

kevins

kevins

@kevins-5Bb80M • Oct 22, 2024
I have seen phone scanners on the web, I am not interested in that, but it does fall around what I am interested in.

I am sure it's possible to listen on 900 MHz and grab the cell phones transmitting their signals. Now each cell phone carrier operates in a range of frequencies and the phones transmit on those frequencies. The tower gets the signal and demodulates the signal.

The question is this, when the signal is demodulated there must be some way to distinguish each individual cell phone, well otherwise it would be chaos. I believe the it something to do with the ESN or sim card. So I imagine the unique id of each phone is transmitted in the signal and not encrypted or encoded or anything like that. Is this true?

thanks,
kevin
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  • durga ch

    durga ch

    @durga-TpX3gO • Feb 22, 2011

    hmm, consider CDMA for examaple.
    Each user is assigned a ' code' in sense , the tx applies the code while sending the signal and the reciver is supposed to apply the same code. That is the reason why CDMA phones cant accommodate any other technology, there hardware doesnot allow them

    if you consider GSM, again the signal is sent in a specific time signal for a definite frequency, so the receiver again is aware to whom the signal needs to be sent back to

    does this help?
    0