How to build a cell phone jammer

Build a cell phone jammer

If you want to build a jammer yourself, then a circuit diagram is of course essential. So when we understand the circuit diagram, what is worth noting?

For any jammer circuit, remember that there are three main important circuits. When they are combined together, the output of that circuit will work as a jammer. The three circuits are

  1. RF amplifier.
  2. Voltage controlled oscillator.
  3. Tuning circuit.

Start build a signal jammer

Simply program a small microntroller to generate a random-noise base signal and possibly the serial control strings for the PLL chip and wire it into the cellfone’s circuit. Ok, that part might be a little tricky, but a little collaboration with the online hacker community could easily produce diagrams for a handful of the more popular phones showing which wires to solder into to inject your rogue signal and activate the RF amp section etc… But all the hard work of creating the RF signal generator and amp and wave shaping circuits and antenna would already be done for you!

So worst case you would have an old cellfone with a small circuit board sandwiched to it externally which would have a PIC or other microntroller on it.

Or even better, invest some time into deciphering how to download a new firmware program into the phone’s main CPU. If you can do that, it would be simple enough to write a small program to do nothing more than send random noise, at full power, on the correct frequency.

An effective jammer does not necessarily need to be outputting a significantly higher power level than the devices it wishes to jam. most Cellfones use CDMA technology which means they are all essentially broadcasting on the same frequency, but they are all synchronized with the base station and transmit different “codes” within that frequency to allow the base station to decipher them individually. However, a single rogue phone on the CDMA frequency that is constantly blasting out garbage noise instead of carefully synched CDMA codes will drown out its immediate neighbors…

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