Tom’s Guide writes about home brew TEMPEST receivers:

Today, dirt-cheap technology and free software make it possible for ordinary citizens to run their own Tempest programs and listen to what their own — and their neighbors’ — electronic devices are doing.

Elliott, a researcher at Boston-based security company Veracode, showed that an inexpensive USB dongle TV tuner costing about $10 can pick up a broad range of signals, which can be “tuned” and interpreted by software-defined radio (SDR) applications running on a laptop computer.