The TGCA is based on the AD8331 integrated circuit of Analog Devices which includes an ultralow noise preamplifier and a variable gain amplifier. The gain of the TGCA is controlled by the voltage ramp generator and increases with the elapsed time, thus compensating the attenuation of the ultrasonic waves over the travelled distance. The logarithmic amplifier is based on the AD8310 integrated circuit of Analog Devices, an ultra-fast responding and highly versatile logarithmic amplifier.