Improvement in detected signal-to-noise ratio is obtained for a periodic signal masked by additive noise and turbulent noise backgrounds. Comparisons are made between autocorrelation, crosscorrelation, and a combination of frequency filtering and crosscorrelation. Although the latter method provided the greatest improvement, the crosscorrelation technique was the most successful single method. It turned out that the maximum improvement obtainable was limited by the dynamic range of the correlator computer and not by errors due to finite averaging time and scanning the delay. The improvement for signals masked by turbulent noise was found to be about 5 db less than that obtained for additive noise.