Time variable gain for long range sonar with chirp sounding signal

The main purpose of applying Time Variable Gain (TVG) in active sonars with digital signal processing is to reduce dynamic range of echo signal and adapt it to the dynamic range of the analogue to digital conversion. With high transmission losses level, the dynamic range of the input signal in long range sonars can be very high and even exceed 200 dB. When chirp sounding signals with matched filtration are used, sonars can reach very long ranges. The article presents optimisation of TVG control for long range sonars. It also looks at the influence of chirp sounding signal compression, the result of digital matched filtration, for the TVG controlling. The examples of obtained results are presented