Method for mitigating spatial aliasing

A method for use with a towed array of hydrophones, for mitigating spatial aliasing to better determine the direction of an incoming underwater acoustic signal comprising the steps of:

• towing an array of at least one hydrophones underwater in a forward motion;
• sensing acoustic energy from an acoustic energy source with said array of at least one hydrophones;
• converting said acoustic energy into a digital electronic signal with said array of at least one hydrophones;
• receiving said digital electronic signal with a data processing computer system joined to said towed array of hydrophones;
• processing said digital electronic signal with said data processing computer system to generate at least one synthetic towed array element and assigning a signal to said at least one synthetic towed array element by time delaying the electronic signal received from the towed array of at least one hydrophones, wherein the time delay is based on the forward motion of the array of at least one hydrophones and a desired separation distance of the array of at least one hydrophones;
• filtering the digital electronic signal, into its frequency components using a bank of filters;
• estimating an observed source frequency ωd based on the Doppler shift due to the movement of the towed array of hydrophones;
• correcting the phase of the at least one synthetic towed array element signal associated with each source frequency component within a main lobe around each frequency component for a look direction θ of each hydrophone of the towed array of at least one hydrophones to compensate for the time delay;
• performing frequency beam forming using the signals from both the array of at least one hydrophones and the at least one synthetic array element;
• and
• generating a graphical representation of a multi-tonal signal from the frequency beam forming of the array elements and the at least one synthetic array element that will indicate the source direction and look direction associated with the acoustic energy source wherein said graphical representation is displayed on a graphical user interface that is joined to the data processing computer system.