Cardioid receive array calibration for active systems

Abstract

Nowadays active detection improvement relies significantly on advanced sensor technology, such as the cardioid receive array that allows the directional (right/left) discrimination of the received signal. However, in cardioid sonar signal processing calibration is a major drawback as the signal level obtained is not directly related to the hydrophone pressure level in the water. In this paper, mathematical expressions are derived for the calibration of the cardioid-processed data using CW and LFM signals. The validity of these expressions is demonstrated with simulated and real active LFM sonar data. In addition, two cardioid beamformers are examined and compared; both algorithms are applied to real and modeled data. Comparisons between line and cardioid array are also obtained.