Signal to Noise Ratio Degradation in Acoustic Receivers

Degradation of Signal to Noise Ratio (SNR) in an acoustic receiver due to circuit elements is studied. Lumped parameter equivalent circuit of a hydrophone and noise equivalent circuit of a preamplifier is used to model the receiver system as an electronic circuit utilising the potential of electrical circuit theory and analysed the acoustic receiver noise performance. As the signal passes through the receiver chain, the thermal noise of hydrophone and various noise sources of the preamplifier get added to the signal, degrading the SNR. An expression for SNR at various locations of the receiver system is developed in terms of the circuit parameters. The effect of equivalent input voltage noise, equivalent input current noise and bias resistor on the total system noise is studied in detail and the results are presented in this paper. The method presented here provides a tool for analysing the acoustic receiver in the electrical domain and to optimize the system performance.