SYSTEM FOR DETECTING WEAK INFORMATION SIGNALS IN NOISY RECEIVER SIGNALS

摘要

A system is provided which permits the detection of a useful signal in a received signal having a low signal to noise ratio. The system includes a band pass filter connected to receive the signal to be processed, an AGC amplifier, and a comparator which compares the output of the amplifier with a threshold or reference level and produces an output during the time this level is exceeded. The output of the comparator is converted into a train of rectangular pulses which are sampled at a clock frequency which is substantially shorter than the minimum duration of the useful signal. A circulating memory receives the samples which are arithmetically summed at each clock time, the arithmetical sum being then compared with a second threshold level to determine whether the received signal is a useful signal.