Abstract: A radar altimeter system uses a microprocessor-based subsystem to process radar signals in software. The subsystem includes a track loop and a verify loop for digital signal processing of the radar signals. The track loop generates a gate pulse and integrates a radar return signal over the time window defined by the gate pulse in order to determine the leading edge of the return pulse. The verify loop positions the gate pulse for maximum overlap with the return pulse and integrates the return pulse over the gate pulse to determine the maximum signal strength of the radar return signal.

Abstract: A differential-mode signal transmission system includes a circuitboard composed of at least one dielectric board substrate and a pair of spaced apart conductive parallel planar signal transmission lines disposed on one surface of the substrate and extending between a pair of edges thereof for providing pass-through transmission of differential-mode signals from one to the opposite edge of the substrate. Preferably, the circuitboard is composed of at least a pair of dielectric board substrates being disposed in face-to-face layered contact with one another and having at least one pair of the spaced apart conductive parallel planar signal transmission lines disposed between the layered substrates along the inner surfaces thereof. Ground planes are provided on the outer surfaces of the layered substrates for electrically shielding the parallel planar transmission line pair.