Title: Radar system having quadrature phase detector compensator

Do you think this is a good invention? Vote now:

Votes so far: For:(0) Against:(0)
Claims: What is claimed is:

1. A method for correcting unbalances between "in phase" and "quadrature" channels of a quadrature phase detector in a digital signal processing radar system comprising the steps of:

a. periodically impressing a test signal having a frequency component f.sub.D on the quadrature phase detector;

b. converting signals produced at the output of the quadrature phase detector in response to such test signal into a set of N complex digital words, such signals being converted at a rate M where M is an integral multiple of f.sub.D and N is equal to the ratio of the rate M to the frequency component f.sub.D ;

c. determining the frequency spectrum described by the set of N complex digital words;

d. deriving correction coefficients in accordance with the determined frequency spectrum; and,

e. applying such correction coefficients to signals produced at the output of the quadrature phase detector in response to radar return signals.

2. In a digital processing radar system wherein a quadrature phase detector is provided to demodulate radar return signals, such demodulated radar signals then being sampled and converted into a set of complex digital words, at a predetermined rate M, an improved apparatus for correcting imbalances between channels of such quadrature phase detector, comprising:

a. means for periodically impressing a test signal having a frequency component f.sub.D on the quadrature phase detector, the frequency f.sub.D being an integral submultiple of M, such phase detector producing an output signal in response thereto; and

b. a compensator responsive to the set of complex digital words and the output signal for deriving correction coefficients.

3. The apparatus as in claim 2 wherein the compensator includes a fast Fourier transformer.

4. The apparatus as in claim 3 wherein the number of points in the fast Fourier transformer is equal to the ratio of the sampling rate M to the frequency f.sub.D.

Other info:

Inventors: Churchill, Frederick E. (Carlisle, MA, US)
Ogar, George W. (Wakefield, MA, US)
Thompson, Bernard J. (Concord, MA, US)

Application Number: 511552
Filing Date: 1974-10-03
Publication_date: 1976-04-13
Assignee: Raytheon Company (Lexington, MA)
Primary Class(es): 342/174 342/194, 342/196
Other Classes:
US Patent Ref:

3794998	Feb, 1974	Pearso, Jr. et al.	343/17.
3883870	May, 1975	Kunz	343/17.

Other Refs:
Primary Examiner: Tubbesing, T. H.
Assistant Examiner:
Attorney: Sharkansky; Richard M., McFarland; Philip J., Pannone; Joseph D.