Abstract: A method for determining the positions of the N array elements of a random rray to an accuracy sufficient to accomplish beam forming is provided where the initial positions of the array elements are known to an accuracy of .lambda..sub.min/2, and where .lambda..sub.min is the wavelength of the highest frequency of any of the M cohering sources which are in the field of the array and where the relative directions are unknown. The method includes the steps of: identifying M cohering sources in the field of the array, each of which emits at least one narrowband frequency, each frequency differing from the adjacent frequency by 1/T, where T is the time period of the measurements; a device for measuring the true bearing of one of the M sources; receiving the M cohering signals at the N array elements; performing a Fast Fourier Transform (FFT) on each of the N element signals; examining the spectrum of each of the N received signals; and from the N spectra, selecting M (M>3) lowest angular frequencies, .omega..

Abstract: Apparatus for determining the bearing of an acoustic source from a selected ocation in an acoustic environment includes a plurality of discrete acoustic sensor elements and a flexible member, having first and second ends, which may be deployed in a linear configuration in the environment. The sensor elements are attached along the flexible member in spaced apart relationship, one of the elements, comprising a lead element, being closer to the first end than any of the other elements. A motion measuring device is coupled to the lead element when the flexible member is deployed in the environment to generate signals which indicate the velocity of the lead sensor element in the environment.

Abstract: This invention relates to an acoustical hologram reconstructor using surf acoustic wave (SAW) devices, which is a major part of apparatus which converts an acoustical hologram into a focused optical image, both having a magnitude and phase. The focused image is ultimately converted to an optical image having intensity variations, which can be viewed on a TV monitor. Two parallel convolvers, implemented by surface wave devices, are required to achieve the necessary speed of signal processing. One convolver loads while the other calculates, and vice versa. Circuitry is included to perform the following three functions required to reconstruct an intensity pattern: (1) multiplication of the hologram data by a focusing correction term; (2) performance of the inverse Fourier transform; (3) squaring and summing the real and imaginary components.

Abstract: An improved method and apparatus for processing electronic signals for use n establishing an improved image display includes storing the electronic and acoustic response of all the detectors in response to impingement thereon by a plane wave-front as stored in a memory. In the operational environment, these stored signals are combined with the transducer response and the signals are combined in such a fashion as to compensate for spatial nonuniformities.