nedoPC.org

The software tunes the IM-Me's radio chip to one frequency at a time, uses the chip's RSSI measurement function, and plots the result as one column on the LCD. It sweeps across the whole screen (132 columns) several times per second, showing a contiguous range of radio frequency activity. The technique works quite well, although there are a few defects. Most notably, harmonics of the IM-Me's 26 MHz crystal show up as spurs on the display.

The frequency ranges supported by my device are 281 - 361, 378 - 481, and 749 - 962 MHz. This is about 50% more than the chip is advertised to support and covers quite a bit of interesting activity in the US including ISM, LMR, television, amateur bands, pagers, and mobile phones. The edges of the bands supported by other batches of chips may differ but probably not by much.

The software supports three bandwidth modes: wide (default), narrow, and ultrawide. Wide mode displays 26.4 MHz of bandwidth in 200 kHz increments. Narrow mode displays 6.6 MHz of bandwidth in 50 kHz increments. Ultrawide mode, shown here with some mobile phone activity, displays 88 MHz of bandwidth in 667 kHz increments.