Monostatic Versus Bistatic SONAR Evaluation with a Backscattering Acoustic Propagation Model

Abstract

In SONAR systems designed for measuring deep ocean bathymetry a monostatic configuration, with the transmitter (Tx) and receiver (Rx) collocated and close to the bottom, is generally assumed to be the most effective. These systems rely on the backscattered component of transmitted acoustic signals, e.g. side scan SONAR, multibeam SONAR. Through the application of a ray tracing acoustic propagation model, TRACEO, and a bottom scattering cross section model, this work tests several geometric configurations of Tx and Rx to investigate which is the most effective. The models were used to calculate the total attenuation suffered by the transmitted signals at various ranges for three different geometric configurations of Tx and Rx. These were: (1) Monostatic, with the Tx and Rx both 100 m from the bottom; (2) Close Bistatic, with Tx 200 m from the bottom and Rx 100 m from the bottom; and (3) Far Bistatic, with Tx near the surface and Rx 100 m from the bottom. Synthetic results show that the best configuration, in terms of transmission loss, is the Close Bistatic case. These results were then evaluated using the SONAR equation to determine each configuration viability for implementation in a SONAR system, given various settings of amplifier on the Tx side and pre-amplifier at the Rx side, with the goal of producing a detectable signal at the receiver. This evaluation confirmed that the geometric configuration with the highest viability was a Close Bistatic configuration, followed by the Monostatic, and finally the Far Bistatic.