Echoscopes incorporating signal processing circuits capable of providing a more complete and useful display of information received as a train of electrical signals. In one circuit, which is essentially a compression amplifier, the amplitude range of the input signal is limited by way of two or three amplitude limiting stages and an adder connected to sum the output of the first and last stages provides an advantageous output to input characteristic for the circuit.The second circuit includes filter means and derivating means to separately process the input signal, and an adder to combine the outputs of these means to obtain a signal of enhanced utility.