Abstract: A method and apparatus for controlling the false alarm rate of a receiver which detects each received signal having a power level greater than a predetermined threshold level which is received within a predetermined detection interval. The receiver is adapted to receive signals in response to source signals having a predetermined transmission period. The signals detected within each transmission period can include an initial signal and a plurality of excess signals received subsequent to the initial signal. The total number of detected signals and the number of excess signals received within the predetermined detection interval are counted and a ratio therebetween is determined. Based upon the ratio of the total number of signals to the number of excess signals, the relationship between the power level of the received signals and the threshold level is adjusted in order to control the false alarm rate of the receiver.

Abstract: A laser doppler velocimeter with laser backscatter discrimination for determining the relative velocity between an optical platform and another target where a laser beam is generated and directed toward the target. A detector produces a doppler signal in response to the detection of the laser beam. Noise and backscatter signals with bandwidths and amplitudes outside selected thresholds are rejected, and the legitimate doppler signal from the target is enhanced.