An aircraft ”RADAR” plotter and tracker

When it was discovered some years ago that cheap "DVB-T" digital TV tuner dongles based on the Realtek RTL2832U chipset could be hacked into serving as veritable SDR's (software defined radios), covering the entire frequency spectrum from 24 MHz to almost 2 GHz, it suddenly became possible to build very affordable ADS-B receivers/decoders (among other applications). ADS-B stands for Automatic Dependent Surveillance - Broadcast, and its digital signals are transmitted on 1090 MHz.