US3573825A
Expired / Lapsed
US
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Radar system
Assignee: Canadian Patents and Development Ltd
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Filing: 1969-06-11
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Granted: 1971-04-06
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Expires: 1989-06-11
Abstract
Abstract A high-accuracy radar altimeter which measures the average height above sloping ground by use of a circuit sensitive to the timing of the mean peak of each return pulse while eliminating the effect of signals reflected from vegetation. Verification of the receipt of a return pulse is achieved by use of Miller circuits which are triggered on by a return pulse and off by a delayed sample of the corresponding transmitted pulse.
Inventors
- 👤 Ray L Westby
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:55
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/02; G01S7/28; G01S7/285; G01S7/292; G01S7/2921
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
209 words
A radar altimeter for accurate determination of mean height above sloping ground, comprising: a. a radar transmitter including an antenna for directing outgoing pulses downwardly from an aircraft to said ground; b. receiving means for detecting return pulses less sharp that the outgoing pulses, the timing of the mean peak of each of which return pulses represents said mean height; c. means connected to said receiving means for detecting occurrence of a predetermined signal level on the leading edge of each return pulse and for generating a first timing signal upon detection of such level, said means connected to said receiving means also detecting the occurrence of the same predetermined signal level on the trailing edge of each return pulse and generating a second timing signal upon detection of such trailing edge level; d. means connected to said transmitter for sampling each outgoing pulse and generating a sync pulse having a predetermined temporal relationship to the leading edge of such outgoing pulse; and e. timing circuit means for generating a mean output signal proportional to the time interval between occurrence of said sync pulse and the mean of the times of occurrence of said first and second timing signals, said mean output signal being representative of said mean height.
Claim 2
Dependent Claim
209 words
A radar altimeter for accurate determination of mean height above sloping ground, comprising: a. a radar transmitter including an antenna for directing outgoing pulses downwardly from an aircraft to said ground; b. receiving means for detecting return pulses less sharp that the outgoing pulses, the timing of the mean peak of each of which return pulses represents said mean height; c. means connected to said receiving means for detecting occurrence of a predetermined signal level on the leading edge of each return pulse and for generating a first timing signal upon detection of such level, said means connected to said receiving means also detecting the occurrence of the same predetermined signal level on the trailing edge of each return pulse and generating a second timing signal upon detection of such trailing edge level; d. means connected to said transmitter for sampling each outgoing pulse and generating a sync pulse having a predetermined temporal relationship to the leading edge of such outgoing pulse; and e. timing circuit means for generating a mean output signal proportional to the time interval between occurrence of said sync pulse and the mean of the times of occurrence of said first and second timing signals, said mean output signal being representative of said mean height.
Claim 3
Dependent Claim
48 words
A radar altimeter according to claim 1, wherein said predetermined signal level is located near the top of each return pulse whereby to minimize the effect of energy reflected by vegetation on the ground and thus to obtain a determination of the mean height above the ground proper.
Claim 4
Dependent Claim
72 words
A radar altimeter according to claim 1, wherein said means for generating a sync pulse includes delay means for ensuring occurrence of said sync pulse later than said first and second timing signals whereby said timing circuit means is triggered on by first and second timing signals consequent upon receipt of a return pulse, and is triggered off by said sync pulse, said time interval thus varying inversely with said mean height.
Claim 5
Dependent Claim
137 words
A radar altimeter according to claim 1, wherein said timing circuit means comprises: i. a first timing circuit connected to be triggered on by said first timing signal; ii. a second timing circuit connected to be triggered on by said second timing signal; iii. said means for generating a sync pulse including delay means for ensuring occurrence of said sync pulse later than said first and second timing signals; iv. means connecting both said timing circuits to be triggered off by said sync pulse; v. said timing circuits generating first and second outputs respectively proportional to the time interval between the first timing signal and the sync pulse and the time interval between the second timing signal and the sync pulse; and vi. means for averaging said first and second outputs to generate said mean output signal.
Claim 6
Dependent Claim
30 words
A radar altimeter according to claim 4, including means for subtracting said mean output signal from a constant to generate a final output signal directly proportional to said mean height.
Claim 7
Dependent Claim
123 words
A radar system corresponding: a. a radar transmitter including an antenna for directing outgoing pulses; b. receiving means connected to said antenna for detecting return pulses and generating at least one timing signal upon detection of each such return pulse; c. means connected to said transmitter for sampling each outgoing pulse and generating a delayed sync pulse having a predetermined temporal relationship to the leading edge of said outgoing pulse, the delay being such as to ensure occurrence of said sync pulse later than said timing signal; and d. timing circuit means connected to be triggered on by said timing signal and subsequently to be triggered off by said sync pulse for generating an output proportional to the time interval between said signals.
Claim 8
Dependent Claim
123 words
A radar system corresponding: a. a radar transmitter including an antenna for directing outgoing pulses; b. receiving means connected to said antenna for detecting return pulses and generating at least one timing signal upon detection of each such return pulse; c. means connected to said transmitter for sampling each outgoing pulse and generating a delayed sync pulse having a predetermined temporal relationship to the leading edge of said outgoing pulse, the delay being such as to ensure occurrence of said sync pulse later than said timing signal; and d. timing circuit means connected to be triggered on by said timing signal and subsequently to be triggered off by said sync pulse for generating an output proportional to the time interval between said signals.
Claim 9
Dependent Claim
121 words
A radar system according to claim 6: e. wherein said receiving means includes means for generating two said timing signals in response to detection of predetermined signal levels on the leading and trailing edges respectively of a said return pulse; f. said timing circuit means comprising first and second timing circuits connected to be triggered on by respective said timing signals and both to be triggered off by said sync pulse; g. said timing circuits generating first and second outputs respectively proportional to the time interval between the first timing signal and the sync pulse and between the second timing signal and the sync pulse; and h. means for averaging said first and second outputs to generate a mean output signal.
Claim 10
Dependent Claim
39 words
A radar system according to claim 7, including means for subtracting said mean output signal from a constant to generate a final output signal directly proportional to the distance of the object reflecting the return pulses to the system.
References Cited (Backward Citations)
US3097355A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-04-05 | 1974-10-05 | 1975-04-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-04-05 | 1978-10-05 | 1979-04-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-04-05 | 1982-10-05 | 1983-04-06 | $7700.00 | Window Closed / Lapsed |