US3950750A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Radar system having quadrature phase detector compensator
Assignee: Raytheon Co
•
Filing: 1974-10-03
•
Granted: 1976-04-13
•
Expires: 1994-10-03
Abstract
Abstract Method and apparatus are disclosed for correcting amplitude and phase imbalances between the "in phase" and "quadrature" channels of a digital signal processor by determining a correction coefficient from a test signal periodically introduced into the quadrature phase detector of a radar system. The frequency spectrum of the signal at the output of the phase detector in response to each such test signal is utilized to produce a correction coefficient for application to radar return signals passing through the phase detector during normal radar operation, thereby providing true quadrature radar return signals for digital processing.
Inventors
- 👤 Frederick E. Churchill
- 👤 George W. Ogar
- 👤 Bernard J. Thompson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 03:29
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/02; G01S7/40; G01S13/00; G01S13/02; G01S13/50; G01S13/52; G01S13/522; G01S13/524; G01S13/53
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
153 words
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 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 D and N is equal to the ratio of the rate M to the frequency component f 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.
Claim 2
Independent Claim
153 words
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 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 D and N is equal to the ratio of the rate M to the frequency component f 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.
Claim 3
Dependent Claim
112 words
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 D on the quadrature phase detector, the frequency f 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.
Claim 4
Dependent Claim
112 words
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 D on the quadrature phase detector, the frequency f 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.
Claim 5
Dependent Claim
14 words
The apparatus as in claim 2 wherein the compensator includes a fast Fourier transformer.
Claim 6
Dependent Claim
32 words
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 D .
References Cited (Backward Citations)
US3794998A
Cited
US3883870A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-04-13 | 1979-10-13 | 1980-04-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-04-13 | 1983-10-13 | 1984-04-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-04-13 | 1987-10-13 | 1988-04-13 | $7700.00 | Window Closed / Lapsed |