US4011561A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Simplified digital conversion for coherent-on-receive pulsed radar system
Assignee: Motorola Solutions Inc
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Filing: 1975-07-07
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Granted: 1977-03-08
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Expires: 1995-07-07
Abstract
Abstract An improvement in a pulsed radar system providing coherent-on-receive signals utilizing digital techniques. The phase of the transmitted signal is compared to the phase of a stable local oscillator and the phase relationship is converted to a complex digial number which is then stored in a suitable short term memory. The received signals are also converted to complex digital numbers containing both the phase relationship to the stable local oscillator and the amplitude of the return video signal. A common signal channel is used for conversion of both the transmitter pulse and the received signals. The digitized received signals are then digitally phase corrected to provide coherence using the stored complex digital numbers for the correction.
Inventors
- 👤 Eric Alexander Dounce
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 12:29
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/02; G01S7/28; G01S7/285; G01S7/288
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
143 words
In a pulsed radar system wherein coherence is achieved in the receiver of the radar system by applying a stored complex digital number, representing the phase relationship between each transmitted pulse and a stable reference oscillator signal, as a correction factor to a series of complex digital numbers, representing the phase relationships between subsequent samples of the received signal and the stable reference oscillator signal, the improvement comprising: means for digitizing the phase relationship of each transmitted pulse with respect to the reference oscillator signal and for digitizing the phase relationships between the received signals and the reference signal; and means for digitally multiplying said digitized phase relationships by the factor e - j2 .sup.πft, where f is equal to one half the video bandwidth of the radar system, to provide real and imaginary parts of digital complex numbers representing said phase relationships.
Claim 2
Dependent Claim
143 words
In a pulsed radar system wherein coherence is achieved in the receiver of the radar system by applying a stored complex digital number, representing the phase relationship between each transmitted pulse and a stable reference oscillator signal, as a correction factor to a series of complex digital numbers, representing the phase relationships between subsequent samples of the received signal and the stable reference oscillator signal, the improvement comprising: means for digitizing the phase relationship of each transmitted pulse with respect to the reference oscillator signal and for digitizing the phase relationships between the received signals and the reference signal; and means for digitally multiplying said digitized phase relationships by the factor e - j2 .sup.πft, where f is equal to one half the video bandwidth of the radar system, to provide real and imaginary parts of digital complex numbers representing said phase relationships.
Claim 3
Dependent Claim
17 words
The improvement according to claim 1 wherein said digitizing means comprises a single analog to digitial converter.
Claim 4
Dependent Claim
29 words
The improvement according to claim 1 wherein said multiplying means comprises a low pass digital filter for eliminating high frequency spectral components due to aliasing in said multiplying means.
Claim 5
Dependent Claim
44 words
The improvement according to claim 1 wherein said digitizing means produces two sequential digital outputs for each sample input, said first digital output representing a real part of the phase relationship and said second digital output representing an imaginary part of the phase relationship.
Claim 6
Dependent Claim
93 words
In a coherent-on-receive radar system, an improved method of converting the phase relationship between each transmitted pulse and a stable reference oscillator signal and between subsequentially sampled received signals and the stable reference oscillator signal to complex digital number form, comprising the steps of: digitizing the phase relationships of the signals sequentially in a single analog to digital converter; and multiplying the digitized signals by the factor e - j2 .sup.πft, where f is equal to one-half the video bandwidth of the radar system, to provide a real and an imaginary complex number.
Claim 7
Dependent Claim
93 words
In a coherent-on-receive radar system, an improved method of converting the phase relationship between each transmitted pulse and a stable reference oscillator signal and between subsequentially sampled received signals and the stable reference oscillator signal to complex digital number form, comprising the steps of: digitizing the phase relationships of the signals sequentially in a single analog to digital converter; and multiplying the digitized signals by the factor e - j2 .sup.πft, where f is equal to one-half the video bandwidth of the radar system, to provide a real and an imaginary complex number.
Claim 8
Dependent Claim
19 words
The improved method according to claim 5 wherein the digitizing step is accomplished two times for each input sample.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-03-07 | 1980-09-06 | 1981-03-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-03-07 | 1984-09-06 | 1985-03-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-03-07 | 1988-09-06 | 1989-03-08 | $7700.00 | Window Closed / Lapsed |