Patent CA1102054A successfully refreshed from Google Patents.
Patent US3895382A successfully refreshed from Google Patents.
US3895382A
Expired / Lapsed
US
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Method and apparatus for measuring passively range and bearing
Assignee: Litchstreet Co
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Filing: 1974-01-31
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Granted: 1975-07-15
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Expires: 1994-01-31
Abstract
Abstract In an aircraft collision avoidance system, a method and apparatus for determining passively the slant range and bearing angle to another transponder equipped aircraft within a selectable proximity to an aircraft (own aircraft) equipped with the collision avoidance system in which the azimuthal lines of position from interrogating standard secondary surveillance radar ground stations to both aircraft and the times of arrival at the own aircraft of the transponder replies of the other aircraft are determined. From such data, the bearing angles to the actual and imaginary locations of the transponder equipped aircraft are calculated and then supplied to a truth table which identifies the bearing angle to the actual location of the transponder equipped aircraft. The slant range to the transponder equipped aircraft is then computed in accordance with a predetermined relationship between the time of arrival of one of the transponder replies and the bearing angle.
Inventors
- 👤 George B Litchford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:55
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/88; G01S13/93; G01S13/933; G01S13/74; G01S13/76; G01S13/78; G01S13/781; G01S11/00; G01S11/02; G01S5/00; G01S5/02; G01S5/0273
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
181 words
In a system for collision avoidance and/or proximity warning indication at an own location utilizing the signals transmitted by scanning beam secondary surveillance radar (SSR) stations and reply messages transmitted by a nearby transponder replying to said SSR signals, apparatus for passively determining the bearing angle from said own location to said transponder comprising: a. means responsive to said SSR ground station signals for generating signals representative of the azimuthal lines of position from selected radar stations to the own location and to the location of said transponder; b. means responsive to selected reply messages transmitted by said transponder and responsive to the SSR ground station signals for providing signals representative of the time of arrival of each of said selected reply messages at said own location; and c. means responsive to signals representative of selected azimuthal lines of position and to the corresponding signals representative of selected times of arrival for providing a signal indicative of the bearing angle from the own location measured from said lines of position to the location in space from which the transponder replies originate.
Claim 2
Dependent Claim
181 words
In a system for collision avoidance and/or proximity warning indication at an own location utilizing the signals transmitted by scanning beam secondary surveillance radar (SSR) stations and reply messages transmitted by a nearby transponder replying to said SSR signals, apparatus for passively determining the bearing angle from said own location to said transponder comprising: a. means responsive to said SSR ground station signals for generating signals representative of the azimuthal lines of position from selected radar stations to the own location and to the location of said transponder; b. means responsive to selected reply messages transmitted by said transponder and responsive to the SSR ground station signals for providing signals representative of the time of arrival of each of said selected reply messages at said own location; and c. means responsive to signals representative of selected azimuthal lines of position and to the corresponding signals representative of selected times of arrival for providing a signal indicative of the bearing angle from the own location measured from said lines of position to the location in space from which the transponder replies originate.
Claim 3
Dependent Claim
53 words
Apparatus according to claim 1 for passively determining the range to said transponder from said own location comprising: d. means responsive to one of said selected times of arrival representative signals and the signal indicative of the bearing angle for providing a signal representing the distance separating said transponder from said own location.
Claim 4
Dependent Claim
103 words
Apparatus according to claim 2 wherein the own location is an aircraft and said transponder is located on another aircraft, further comprising: e. means for decoding altitude reporting signals forming a part of the transponder replies from the other aircraft; f. means for producing similar own aircraft altitude signals; g. means for comparing said altitude reporting signals and said similar own aircraft altitude signals to produce common altitude stratum signals; and h. means responsive to the presence of said common altitude stratum signals for controlling the means for providing the bearing angle indicative signals and the means for providing the distance indicative signals.
Claim 5
Dependent Claim
57 words
Apparatus according to claim 3 further comprising: i. means for decodIng the identity reporting signals in the transponder replies of the other aircraft; j. means for determining correspondence between said identity reporting signals; and k. means for controlling the means for providing the bearing angle indicative signals in accordance with the correspondence between said identity reporting signals.
Claim 6
Dependent Claim
61 words
Apparatus according to claim 2 further comprising: l. first indicator means responsive to said range representative signal for displaying the distance separating the own location from said transponder; and m. second indicator means responsive to said range representative signal for providing signals indicative of the rate of change of said range representative signal and inclusing means for displaying said range rate.
Claim 7
Dependent Claim
24 words
Apparatus according to claim 2 comprising: n. third indicator means responsive to the bearing angle representative signal for displaying the bearing of said transponder.
Claim 8
Dependent Claim
75 words
Apparatus according to claim 2 wherein the means for providing a bearing angle indicative signal comprises means responsive to the signals representative of selected azimuthal lines of position and to the corresponding signals representative of selected times of arrival for providing signals indicative of the bearing angles from the own location measured from said lines of position to the locations in space from which transponder replies actually originate and from which transponder replies apparently originate.
Claim 9
Dependent Claim
76 words
Apparatus according to claim 7 wherein the means for providing a bearing angle indicative signal comprises means responsive to signals representative of selected azimuthal lines of position originating from geographically separated SSR stations for providing signals representative of the angular differences between said selected azimuthal lines of position and means responsive to said angular difference signals and to signals representative of the corresponding times of arrival for generating said actual and apparent bearing angle indicative signals.
Claim 10
Dependent Claim
90 words
Apparatus according to claim 7 further comprising: o. truth table means responsive to preselected relationships between said bearing angle indicative signals, said truth table means comprising means for identifying said signals as indicative of either the true bearing angle to the locations in space from which the transponder replies actually originate or the false bearing angles to the locations in space from which the transponder replies apparently originate and means for transmitting the signal representative of the actual bearing angle and blocking the signals representative of the apparent bearing angles.
Claim 11
Dependent Claim
127 words
Apparatus according to claim 9 wherein two secondary surveillance radar stations interrogate said own location and said transponder and wherein the truth table means comprises means for assigning said actual and apparent bearing angle representative signals selected polarities in accordance with their angular magnitudes, lead/lag logic means responsive to the reply messages transmitted by said transponder for developing signals with selected polarities in accordance with the azimuthal positioning of said transponder relative to the own location''s azimuth from the secondary surveillance radars, means for comparing said assigned polarities and the signals developed by said lead/lag logic means to determine the true bearing by polarity, and means controlled by said comparator means for transmitting the actual bearing angle representative signal and eliminating the apparent bearing angle representative signals.
Claim 12
Dependent Claim
89 words
Apparatus according to claim 9 wherein at least three secondary surveillance radar stations interrogate said own location and said transponder and wherein said means for providing a bearing angle indicative signal comprises means responsive to selected azimuthal lines of position and to corresponding signals representative of selected times of arrival for developing signals indicative of at least four bearing angles as measureD from the azimuthal lines of position from one of said secondary surveillance radar stations to the locations in space from which transponder replies actually and apparently originate.
Claim 13
Dependent Claim
71 words
Apparatus according to claim 11 wherein the truth table means comprises compartor means responsive to said bearing angle indicative signals for determining the coincidence in magnitude between two of said bearing signals, such two signals being essentially equal and consequently representative of the actual bearing angle, and further comprising means controlled by said comparator means for transmitting the actual bearing angle representative signal and eliminating the apparent bearing angle representative signals.
Claim 14
Independent Claim
138 words
A method for passively determining the bearing of a transponder within a selectable proximity to one''s own position from the interrogation replies of the transponder in the coverage of a secondary radar system, comprising the steps of: a. developing signals representative of the lines of position to said own position and to said transponder position from selected radar stations interrogating the transponder and said own position; b. developing signals representative of the times of arrival at said own station of each of said interrogation replies from the transponder to the selected secondary surveillance radars; c. establishing a preselected relationship between said lines of position and said times of arrival signals; and d. developing a signal representing the bearing angle to the transponder in accordance with the preselected relationship between said lines of position and times of arrival signals.
Claim 15
Independent Claim
138 words
A method for passively determining the bearing of a transponder within a selectable proximity to one''s own position from the interrogation replies of the transponder in the coverage of a secondary radar system, comprising the steps of: a. developing signals representative of the lines of position to said own position and to said transponder position from selected radar stations interrogating the transponder and said own position; b. developing signals representative of the times of arrival at said own station of each of said interrogation replies from the transponder to the selected secondary surveillance radars; c. establishing a preselected relationship between said lines of position and said times of arrival signals; and d. developing a signal representing the bearing angle to the transponder in accordance with the preselected relationship between said lines of position and times of arrival signals.
Claim 16
Dependent Claim
47 words
The passive method according to claim 13 comprising the further step of: e. developing a signal representing the range from said own position to the transponder in accordance with a preselected relationship between said bearing angle signal and at least one of said time of arrival signals.
Claim 17
Dependent Claim
75 words
The passive method according to claim 14 wherein the transponder is carried by an aircraft and comprising the further steps of: f. decoding the altitude reporting signals contained in said transponder replies; g. comparing the decoded altitude of said transponder with the altitude of said own position; and h. controlling the development of the bearing angle signal in accordance with the difference between the altitude of said own position and the altitude of said transponder.
Claim 18
Dependent Claim
60 words
The passive method according to claim 14 wherein the transponder is carried by an aircraft and comprising the further steps of: i. decoding the identity reporting signals in said transponder replies; j. comparing the decoded identities of the transponder; and k. controlling the development of the bearing angle signal in accordance with the coincidence between the identities of the transponder.
Claim 19
Dependent Claim
40 words
The passive method according to claim 14 comprising the further steps of: l. displaying the distance separating the own position from the transponder; and m. displaying the rate of change in the distance separating the own position from the transponder.
Claim 20
Dependent Claim
20 words
The passive method according to claim 14 comprising the further step of: n. displaying the bearing angle to the transponder.
Claim 21
Dependent Claim
80 words
The passive method according to claim 14 comprising the further steps of: o. developing signals indicating the rate of change in the range between said own position and said transponder; p. developing command signals corresponding to the time separation between said own position and said transponder; and q. combining the range, range rate and bearing angle signals to control the development of the command signal in accordance with the movement by the transponder toward or away from said own position.
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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) | 1978-07-14 | 1979-01-13 | 1979-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-14 | 1983-01-13 | 1983-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-14 | 1987-01-13 | 1987-07-15 | $7700.00 | Window Closed / Lapsed |