Detection of Command-Initiated Improvised Explosive Devices Using Unintentional Radiated Emissions
Drs Daryl Beetner and Todd Hubing
All active electronic devices radiate electromagnetic energy. Radio receivers (not just the transmitters) may be significant sources of electromagnetic radiation. The radiation from radio receivers might be used to detect improvised electronic devices (IEDs) as the receiver must be active to function, as electrical activity is easily coupled to the receiver antenna and then radiated, and as the radiated signal is often unique to the receiver.
The following pictures are linked to audio files that give a sense for the unintentional radiated electromagnetic emissions from several radio receivers typically used in IEDs. High-frequency emissions were measured from the devices and then resampled at audio frequencies to demonstrate the unique characteristics of each signal. Note that the signals are unintentional and are present whenever the receiver is turned on.
(click picture to hear audio version of radiated emissions)
Toy truck (notice the chirp of the receiver)
Car alarm (notice the high-pitch chirp of the receiver)
Wireless phone (notice the clicking sound made by the receiver)
Cellphone (notice the high-pitch tone of the receiver)
Wireless doorbell (notice the high-pitch chirp of the receiver)