Beamforming Narrowband and Broadband Signals

The history of beamforming in sonar applications goes back many years. Perhaps Collodon and Sturm’s use of a horn receiver in their 1826 measurement of the speed of sound in water is a first example. Their 13-km range certainly required a receiver with a good beam pattern to increase the signal to a measureable level. Although receivers have changed over the years, beamforming is still an active area of interest and research. Modern sonars often utilize multiple sensors in an array configuration. More sensors yield more signal information and can help suppress noise and interference. The key to extracting information from the array is to exploit the fact that the signals arrive at the different sensors at different times due to the array geometry and signal angle. An example of the time delay for a signal incident on two sensors is shown below.