Abstract: In a police radar warning receiver with a self-contained battery source of supply, battery life may be prolonged by duty cycling the RF front end circuitry of the receiver and, especially, the swept oscillator thereof at a duty cycle rate not greater than 25% with the circuitry being energized not more than once every approximately one-half second.

Abstract: A radar warning receiver is provided having a police radar signal band discrimination circuit which generates evaluation signals, the state of which indicates the voltage level relative a threshold voltage of a discriminator output as the local oscillator is swept through the radar bands. The times during which the evaluation signals are in one state or the other are utilized to identify in which band the received signal is operating (e.g., X-band or K-band).

Abstract: A radar receiver for detecting quasi-harmonically related radar signals includes an antenna system (10) having a mixer (15) included therein. One harmonic from a local oscillator (20) mixes with a signal at a first frequency to produce an intermediate frequency, and another harmonic of the local oscillator mixes with an input signal at a second frequency also to produce an intermediate frequency. A second mixer (30) and local oscillator (40) may be provided. A bandwidth limited signal detecting system preferably includes a band pass filter (50), a limiting IF amplifier (55) and a frequency discriminator (60). The frequency of either the first or second local oscillator is repeatedly varied by a sweep generator (35) to insure that the presence of a radar signal will pass through the band pass filter (50) and be detected.