Abstract: A method of detecting breaks in a porous element in a material separator is disclosed. A shielding is created in the material separator to form a barrier to RF energy. The shielding is formed with a path through the barrier capable of allowing RF energy and material to flow therethrough. The electrically conductive porous element is positioned fully across the path. An RF signal is transmitted on one side of the porous element, and signal levels of the RF signal are detected on the other side of the porous element, such that the detected RF signal crosses the porous element. A baseline signal strength indicator is established from the detected signal levels using an unbroken porous element. An operative signal strength indicator is generated from the detected signal levels. Breaks in the porous element are detected by comparing the operative signal strength indicator against the baseline signal strength indicator.

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 warning receiver is provided having a police radar signal detection 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 band. The times during which the evaluation signals are in one state or the other are utilized to identify whether the received signal is from a fixed frequency (e.g., police radar) source or a variable frequency source (e.g., spurious signals).