False alarms in time-of-arrival estimators

The problem of unwanted detection of input noise interpreted as useful pulses in Delay Attenuate and Compare (DAC) circuits is considered. The performance of DAC alone is examined and compared to the performance when provided with two different protection circuits based on signal amplitude and signal width. Formulas for computing the false alarm time for Gaussian noise are computed and applied to several false alarm examples. The correctness of the formulas is verified by comparison with experimental results. Both types of circuits are found to assure the DAC circuit adequate protection for the L-band precision Distance Measuring Equipment case. In other applications requiring higher false alarm time the two circuits can be jointly adopted.