Naval Warning department at Military Technical College (MTC) designed Echo Sounder systems for measuring sea depths. These systems have helped MTC teams achieve significant success in international robotic competitions. However, when students graduate, their knowledge is often lost. This paper documents the process of developing a low noise dual band echo sounder with long range capability using FPGA for future MTC projects. Two dual band-hydrophones resonate at 50 kHz and 200 kHz were used for transmission and reception to minimize the cost of the project. FPGA is used to generate pulses with 10 Hz period repetition frequency (PRF) which can be controlled remotely from PC using Universal Asynchronous Receiver and Transmitter (UART) protocol. Echo received is attenuated proportional to the delay time. So, a Time Variable Gain (TVG) control was developed to control the amplifier with a totally controlled gain properties using PC. Then, amplified signal was detected using enhanced envelope detection algorithm applied to FPGA. This paper
summarizes the results of the project.