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The double-threshold method of detection calls for m or more detections in n consecutive trials to decide that a target is present. With the video coincidence techniques described, the requirement is m or more consecutive pairs, or triples, in n consecutive trials. The latter methods may increase the resistance to random interference, but a certain price has to be paid in normal radar-detection range. Important questions are, 1) If the interference has a probability p of exceeding the first threshold, what is the probability that a false target will be formed using these different techniques? 2) What is the required signal-to-noise ratio for a given probability of detection when the rate of false alarm is held constant for all three techniques? The paper develops mathematical formulas to answer such questions, and also presents graphs for the cases n = 10, 20 and 30 hits per target. Examples are worked out for n = 10.