US3757324A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Proximity indication with range and bearing measurements
Assignee: Litchstreet Co
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Filing: 1971-09-15
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Granted: 1973-09-04
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Expires: 1991-09-15
Abstract
Abstract Proximity indication and evaluation for aircraft, using only the signals emitted by secondary surveillance radar and cooperating transponders, to detect intrusion in a monitored proximity volume and determine slant range and relative bearing to the intruder.
Inventors
- 👤 G Litchford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:20
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/74; G01S13/76; G01S13/78; G01S13/781
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
303 words
The method of determining the relative bearing from one''s own location of a first transponder to the location of another transponder within the service area of a selected secondary surveillance radar that omniazimuthally transmits a reference signal as the main radar beam sweeps through a standardized reference direction, such as magnetic North, said method comprising the steps of: a. receiving said reference signals, b. receiving interrogation signals from said radar as the main beam sweeps by one''s own location, c. measuring the time interval between successive reception of one of said reference and said interrogation signals and producing a quantitative first representation of the main beam rotation interval, d. measuring and producing a quantitative second representation of the time interval between reception of a reference signal and reception of the next subsequently received interrogation signal, e. producing a quantitative representation phi of the quotient of the value said second representation divided by the value of said first representation, f. encoding both transponders to transmit a range command signal in reply to received interrogations, g. receiving the other''s transponders replies at each transponder, h. triggering each transponder to trasmit a reply in response to a range command signal received from the other, j. measuring and producing a quantitative representation Y of the time interval between each transponder transmission and the reply received in response thereto, j. measuring and producing a quantitative representation Y + X of the time interval between one''s own reply To an interrogation from said SSR or a simulation thereof and reception of a corresponding reply from the other''s transponder, k. producing a quantitative representation X of the algebraic difference between Y + X and Y, l. producing a quantitative representation theta of the cos 1X/Y, and m. producing a quantitative representation of the algebraic sum of phi and theta .
Claim 2
Independent Claim
303 words
The method of determining the relative bearing from one''s own location of a first transponder to the location of another transponder within the service area of a selected secondary surveillance radar that omniazimuthally transmits a reference signal as the main radar beam sweeps through a standardized reference direction, such as magnetic North, said method comprising the steps of: a. receiving said reference signals, b. receiving interrogation signals from said radar as the main beam sweeps by one''s own location, c. measuring the time interval between successive reception of one of said reference and said interrogation signals and producing a quantitative first representation of the main beam rotation interval, d. measuring and producing a quantitative second representation of the time interval between reception of a reference signal and reception of the next subsequently received interrogation signal, e. producing a quantitative representation phi of the quotient of the value said second representation divided by the value of said first representation, f. encoding both transponders to transmit a range command signal in reply to received interrogations, g. receiving the other''s transponders replies at each transponder, h. triggering each transponder to trasmit a reply in response to a range command signal received from the other, j. measuring and producing a quantitative representation Y of the time interval between each transponder transmission and the reply received in response thereto, j. measuring and producing a quantitative representation Y + X of the time interval between one''s own reply To an interrogation from said SSR or a simulation thereof and reception of a corresponding reply from the other''s transponder, k. producing a quantitative representation X of the algebraic difference between Y + X and Y, l. producing a quantitative representation theta of the cos 1X/Y, and m. producing a quantitative representation of the algebraic sum of phi and theta .
Claim 3
Dependent Claim
39 words
The method set forth in claim 1, further including the steps of: n. producing a quantitative representation H of one''s own heading, and o. producing a quantitative representation B of the algebraic difference between phi + theta and H.
Claim 4
Dependent Claim
298 words
Apparatus for determining the slant range Y between an own transponder and another similarly equipped station, comprising: a. means for encoding the transponder to transmit a range command signal superimposed on its normal reply format, b. means for receiving another''s transponder transmissions, c. means for triggering the transponder to transmit a reply in response to a range command signal received from another transponder, d. means for measuring the time interval between an own transponder transmission and the other''s reply received in response thereto, e. means for producing a quantitative representation of said measured interval, f. means responsive to signals received by the own transponder from a selected secondary surveillance radar to produce a continuous train of synthetic pulses with a substantially constant pulse repetition period, each pulse having a predetermined time relation with respect to one of the own transponder reply pulses when the latter occur, g. means for measuring the time interval between a said synthetic pulse and the reception of a corresponding reply from another''s transponder to produce a quantitative representation Y + X thereof, h. algebraic subtractor means for producing a quantitative representation X of the difference between Y + X and Y, i. a divider device for producing a quantitative representation of the quotient X/Y, j. a function generator for producing a quantitative representation 0 of the function cos 1X/Y k. means for producing a quantitative representation phi of one''s own bearing from the selected secondary surveillance radar, l. an adding device for producing a quantitative representation phi + theta of the sum of said representations phi and theta , m. compass means for producing a quantitative representation H of one''s own heading, and n. a subtracting device for producing a quantitative representation B of the algebraic difference between phi + 0 and H.
Claim 5
Dependent Claim
298 words
Apparatus for determining the slant range Y between an own transponder and another similarly equipped station, comprising: a. means for encoding the transponder to transmit a range command signal superimposed on its normal reply format, b. means for receiving another''s transponder transmissions, c. means for triggering the transponder to transmit a reply in response to a range command signal received from another transponder, d. means for measuring the time interval between an own transponder transmission and the other''s reply received in response thereto, e. means for producing a quantitative representation of said measured interval, f. means responsive to signals received by the own transponder from a selected secondary surveillance radar to produce a continuous train of synthetic pulses with a substantially constant pulse repetition period, each pulse having a predetermined time relation with respect to one of the own transponder reply pulses when the latter occur, g. means for measuring the time interval between a said synthetic pulse and the reception of a corresponding reply from another''s transponder to produce a quantitative representation Y + X thereof, h. algebraic subtractor means for producing a quantitative representation X of the difference between Y + X and Y, i. a divider device for producing a quantitative representation of the quotient X/Y, j. a function generator for producing a quantitative representation 0 of the function cos 1X/Y k. means for producing a quantitative representation phi of one''s own bearing from the selected secondary surveillance radar, l. an adding device for producing a quantitative representation phi + theta of the sum of said representations phi and theta , m. compass means for producing a quantitative representation H of one''s own heading, and n. a subtracting device for producing a quantitative representation B of the algebraic difference between phi + 0 and H.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-03 | 1977-03-05 | 1977-09-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-03 | 1981-03-05 | 1981-09-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-03 | 1985-03-05 | 1985-09-04 | $7700.00 | Window Closed / Lapsed |