US 4,283,767 A · Multiple correlator reference processor

Abstract

A signal processor for use with an array of antenna elements comprises a plurality of pairs of receiver channels which receive signals from respective halves of the array. The component of the signals resulting from noise, such as the noise generated within the ocean, is substantially decorrelated between the respective halves of the array, while a component of the signal obtained from a source of a desired signal is coherent between the two halves of the array. The signals in each pair of channels are translated to intermediate frequencies by mixing the signals with reference signals of differing frequencies in each of the respective pairs of channels. The translated signals in each pair of channels are then multiplied together to produce a signal of substantially constant amplitude which is suitable for detection, or for a bearing deviation indication. Output signals of the respective multipliers are summed together and passed through a low pass filter having a pass band approximately equal to the reciprocal of the anticipated dwell time of the signal source within the beam width of the array of antenna elements. The uncorrelated noise results in an alternating component in the products of the respective multipliers which are substantially cancelled in the summing and filtering to produce a higher signal-to-noise ratio.

Claims7

Dependent claims

A data processing system comprising:

a plurality of pairs of signal processing channels each channel of a pair being response to a different one of two input signals, each of said channels having mixing means for translating said input signal to an intermediate frequency, each of said channels producing output signals having the same waveform in the absence of noise;
means for generating a set of reference signals of different frequencies, individual ones of said reference signals being coupled to said mixing means in respective pairs of said channels to provide mixer output frequency signals having a frequency less than said input signals, the frequencies of respective ones of said reference signals being separated by an amount of frequency which is larger than the bandwidth of said input signals;
means for multiplying the output signal of the mixer of one channel of a pair with the output signal of the mixer in the other channel of said pair to provide a channel pair output signal;
and
means for combining the channel pair output signals produced by the multiplying means of each pair of said signal processing channels to produce a combined signal wherein undulations induced by noise in the input signals each of said channels combine incoherently for a reduction in noise power while a component of said combined signal obtained from said input signals is coherently combined for increasing the ratio of signal power relative to noise power.

2 more elements

Dependencies are inferred from the claim text.

Multiple correlator reference processor

Life of this patent

Multiple correlator reference processor

Life of this patent

Abstract

Claims7