US3896436A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Doppler radar receiver
Assignee: MINI OF AVIAT IN HER MAJESTY S
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Filing: 1962-11-20
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Granted: 1975-07-22
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Expires: 1982-11-20
Abstract
Abstract 1. A Doppler radar system, wherein a phase-sensitive detector demodulates a Doppler signal derived from an incoming signal from a moving target, the detector using a reference signal of the same frequency as the Doppler signal, comprising A TRANSMITTER, A PHASE SENSITIVE DETECTOR FOR DEMODULATING A Doppler signal, TWO COHERENT INCOMING SIGNAL DETECTORS EACH FED WITH REFERENCE SIGNAL FROM THE TRANSMITTER AND VIA DIVIDED PATHS WITH THE SAME REFLECTED INCOMING SIGNALS FROM A TARGET, TWO Doppler signal feed paths, one feeding a Doppler signal from one coherent detector to the signal input of the phase sensitive detector and the other feeding a Doppler signal from the other coherent detector to the reference input of the phase sensitive detector, PHASE SHIFT MEANS CONNECTED IN THE INCOMING SIGNAL PATH TO ONE OF THE COHERENT DETECTORS FOR INTRODUCING A QUADRATURE PHASE SHIFT BETWEEN THE TWO INCOMING SIGNALS APPLIED TO THE COHERENT DETECTORS AND, FURTHER PHASE SHIFT MEANS CONNECTED IN ONE OF THE FEEDPATHS TO THE PHASE SENSITIVE DETECTOR FOR INTRODUCING A FURTHER QUADRATURE PHASE SHIFT BETWEEN THE Doppler signals fed to the phase sensitive detector, whereby UNWANTED Doppler frequency double sideband signals in the outputs of the coherent detectors due to noise modulated transmitter signals mixed with the incoming signals result in opposing signals in the output of the phase sensitive detector.
Inventors
- 👤 Gerald Frederic Johnson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 00:03
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/06; G01S13/42; G01S13/44; G01S13/449; G01S13/50; G01S13/58; G01S13/585; G01S13/586; G01S13/66; G01S13/68; G01S13/685
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
218 words
A Doppler radar system, wherein a phase-sensitive detector demodulates a Doppler signal derived from an incoming signal from a moving target, the detector using a reference signal of the same frequency as the Doppler signal, comprising a transmitter, a phase sensitive detector for demodulating a Doppler signal, two coherent incoming signal detectors each fed with reference signal from the transmitter and via divided paths with the same reflected incoming signals from a target, two Doppler signal feed paths, one feeding a Doppler signal from one coherent detector to the signal input of the phase sensitive detector and the other feeding a Doppler signal from the other coherent detector to the reference input of the phase sensitive detector, phase shift means connected in the incoming signal path to one of the coherent detectors for introducing a quadrature phase shift between the two incoming signals applied to the coherent detectors and, further phase shift means connected in one of the feedpaths to the phase sensitive detector for introducing a further quadrature phase shift between the Doppler signals fed to the phase sensitive detector, whereby unwanted Doppler frequency double sideband signals in the outputs of the coherent detectors due to noise modulated transmitter signals mixed with the incoming signals result in opposing signals in the output of the phase sensitive detector.
Claim 2
Dependent Claim
218 words
A Doppler radar system, wherein a phase-sensitive detector demodulates a Doppler signal derived from an incoming signal from a moving target, the detector using a reference signal of the same frequency as the Doppler signal, comprising a transmitter, a phase sensitive detector for demodulating a Doppler signal, two coherent incoming signal detectors each fed with reference signal from the transmitter and via divided paths with the same reflected incoming signals from a target, two Doppler signal feed paths, one feeding a Doppler signal from one coherent detector to the signal input of the phase sensitive detector and the other feeding a Doppler signal from the other coherent detector to the reference input of the phase sensitive detector, phase shift means connected in the incoming signal path to one of the coherent detectors for introducing a quadrature phase shift between the two incoming signals applied to the coherent detectors and, further phase shift means connected in one of the feedpaths to the phase sensitive detector for introducing a further quadrature phase shift between the Doppler signals fed to the phase sensitive detector, whereby unwanted Doppler frequency double sideband signals in the outputs of the coherent detectors due to noise modulated transmitter signals mixed with the incoming signals result in opposing signals in the output of the phase sensitive detector.
Claim 3
Dependent Claim
27 words
A Doppler radar system as claimed in claim 1, wherein switching means are provided for switching the first-mentioned phase shift means into a chosen incoming signal path.
Claim 4
Dependent Claim
25 words
A Doppler radar system as claimed in claim 1, wherein switching means are provided for switching the further phase shift means into a chosen feedpath.
Claim 5
Dependent Claim
54 words
A Doppler radar system as claimed in claim 1, wherein speedgate means are provided between the coherent detectors and the phase sensitive detector in which speedgate mixers having a common speedgate oscillator change the frequency of the Doppler signals and narrow band fixed-frequency speedgate amplifiers pass the resulting signals to the phase sensitive detector.
Claim 6
Dependent Claim
46 words
A Doppler radar system as claimed in claim 4, wherein automatic gain control means in that one of the speedgate amplifiers connected to the signal input of the phase sensitive detector is controlled by a signal fed back from the output of the phase sensitive detector.
Claim 7
Dependent Claim
66 words
A Doppler radar system as claimed in claim 4, wherein two auxiliary mixers receive outputs from the speedgate amplifiers, the mixers having a common oscillator operating at speedgate amplifier frequency, and low pass filters feed the outputs of the auxiliary mixers to signal and reference inputs of an auxiliary phase sensitive detector, a differentiator circuit being connected in one of the inputs of the auxiliary detector.
Claim 8
Dependent Claim
30 words
A Doppler radar system as claimed in claim 6, wherein a control path connects the output of the auxiliary phase sensitive detector to control the frequency of the speedgate oscillator.
Claim 9
Dependent Claim
54 words
A Doppler radar system as claimed in claim 1 wherein a radar receiver comprises a multi-horn aerial recEiver having a sum and a difference channel, the sum channel constituting the incoming signal path to the aforesaid other coherent detector and the difference channel constituting the incoming signal path to the aforesaid one coherent detector.
Claim 10
Dependent Claim
74 words
A Doppler radar system as claimed in claim 8, wherein a second difference channel is provided, a third coherent detector is fed from the second difference channel, and a second phase sensitive detector having the same reference signal source as the first phase sensitive detector is connected at its signal input to the output of the third coherent detector, the phase of the second difference channel being the same as that of the first.
Claim 11
Dependent Claim
22 words
A Doppler radar system as claimed in claim 8, wherein a limiter is connected in the phase sensitive detector reference signal source.
Claim 12
Dependent Claim
16 words
A Doppler radar system as claimed in claim 10, wherein the limiter is a regenerative limiter.
Claim 13
Dependent Claim
38 words
A Doppler radar system as claimed in claim 1, wherein the coherent detectors operate at intermediate frequency and the first mentioned phase shift means is, or are, located on the input side of the I.F. amplifier, or amplifiers.
Claim 14
Dependent Claim
37 words
A Doppler radar system as claimed in claim 1, wherein the coherent detectors operate at intermediate frequency and the first-mentioned quadrature phase shift means comprises predetermined lengths of connecting cable at the inputs of the coherent detectors.
Claim 15
Dependent Claim
126 words
A Doppler radar system of the kind in which a phase sensitive detector demodulates a Doppler signal using a reference signal at the same frequency as the Doppler signal, comprising two matched coherent detectors, means for feeding the said two matched coherent detectors with incoming signals from a moving target, means for feeding the said two matched coherent detectors with the radar system transmitter signal as a reference signal, a phase sensitive detector, means for feeding the phase sensitive detector with the separate outputs of the said two coherent detectors, quadrature phase shift means connected between the signal input channel and one of the two coherent detectors, and further quadrature phase shift means connected between one of the two coherent detectors and the phase sensitive detector.
Claim 16
Dependent Claim
126 words
A Doppler radar system of the kind in which a phase sensitive detector demodulates a Doppler signal using a reference signal at the same frequency as the Doppler signal, comprising two matched coherent detectors, means for feeding the said two matched coherent detectors with incoming signals from a moving target, means for feeding the said two matched coherent detectors with the radar system transmitter signal as a reference signal, a phase sensitive detector, means for feeding the phase sensitive detector with the separate outputs of the said two coherent detectors, quadrature phase shift means connected between the signal input channel and one of the two coherent detectors, and further quadrature phase shift means connected between one of the two coherent detectors and the phase sensitive detector.
Claim 17
Dependent Claim
129 words
A Doppler radar system of the kind which comprises a first coherent detector connected to detect a Doppler signal from an incoming signal reflected by a moving target, the said first coherent detector deriving its reference signal from the radar transmitter, and a phase sensitive detector demodulates the Doppler signal, its reference signal being of the same frequency as the Doppler signal and being obtained from the incoming signal by a second coherent detector having the same reference signal as the said first coherent detector; and further comprising a first quadrature phase shift means connected between the input signal channel and one of the two said coherent detectors and a second quadrature phase shift means connected between one of the said coherent detectors and the said phase sensitive detector.
Claim 18
Dependent Claim
129 words
A Doppler radar system of the kind which comprises a first coherent detector connected to detect a Doppler signal from an incoming signal reflected by a moving target, the said first coherent detector deriving its reference signal from the radar transmitter, and a phase sensitive detector demodulates the Doppler signal, its reference signal being of the same frequency as the Doppler signal and being obtained from the incoming signal by a second coherent detector having the same reference signal as the said first coherent detector; and further comprising a first quadrature phase shift means connected between the input signal channel and one of the two said coherent detectors and a second quadrature phase shift means connected between one of the said coherent detectors and the said phase sensitive detector.
References Cited (Backward Citations)
US3003147A
Cited
US3092832A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-07-21 | 1979-01-20 | 1979-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-21 | 1983-01-20 | 1983-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-21 | 1987-01-20 | 1987-07-22 | $7700.00 | Window Closed / Lapsed |