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Retention and display of echo return history allows the sonar operator to see what areas of the ocean consistently send back echoes, indicating the probability of a target. Own ship's motion causes the returns to be displayed at different points as time progresses and the echo indications associated with a single target may be so widely separated that the operator fails to correlate them. The combination of moderate ship speeds, in the order of 15 knots, and long periods between pulse transmissions as in the proposed non-alerting search-track modes may cause a five period history to be dispersed over 8 or more range bins or 4 bearing bins even with a stationary target. Investigation of the results and feasibility of compensation for own ship's motion on the search display seems justified.