Patent ID: 7123181

Claim:
In a system that does not rely on illuminating a target, a surveillance method for passively detecting from its spectral signature the identity of a received signal from an unilluminated source that is transmitting a signal, comprising the steps of: deploying a battery-powered unit having a spectrum analyzer that outputs a series of spectral lines, the position and amplitude of which characterize the identity of a received signal from an unilluminated signal source, the battery-powered unit having a signal source recognition unit coupled to the spectrum analyzer for analyzing the spectral content of the received signal to ascertain the identity of the signal source, and a transmitter for transmitting the results of the signal source recognition unit to a remote location, said spectrum analyzer including a single dual chirp generator and both a first dispersive delay line and a second dispersive delay line, with the two different chirps from the dual chirp generator matched to the respective delay lines, whereby power consumption is limited through the use of a single chirp generator thus to maximize the longevity of the battery powered unit deployed; and, receiving the transmittal signal at the remote location and providing an indication of the presence and identity of the unilluminated signal source.