This portable 2.4 GHz Spectrum Analyzer is built inside a cell phone case, Nokia 3410, and used the phone’s graphical LCD to display measuring results. It uses AVR ATMega8 as main controller and CYWM6935 module. The software is written in C using arv-gcc under Windows (WinAVR). The program runs continuously and make around six or seven scans (from 2400 up to 2495 MHz) per second, displaying data in almost real time. There are three display modes implemented: fast, slow, and exposure.
The Spectrum Analyzer project can be used to distinguish between different devices: WI-FI signals, Wireless FM cameras (and ATV signals), Bluetooth devices, Microwave ovens and other device like wireless keyboards. But you need a time to learn the pattern. Miguel A. Vallejo, the designer, said that the most used frequency is always the segment 2450 – 2470 MHz, wifi channel 11. I suppose this is the common default channel in many wireless routers and access points.