US3935574A
Expired / Lapsed
US
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Signal source position-determining process
Assignee: United States Department of the Navy
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Filing: 1974-04-15
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Granted: 1976-01-27
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Expires: 1994-04-15
Abstract
Abstract A signal source position is determined using an angle-measuring, interferometer system employing a longitudinal antenna array having a baseline length greater than the signal wavelength. The long, multi-lambda (n lambda ) baseline produces ambiguous phase measurement ( ). Thus, the true angular position or bearing could correspond either to phi , or phi +/-360 DEG , or phi +/-2.360 DEG , - phi +/-(n-1)360 DEG , or phi -n .360 DEG . Ambiguities are resolved by the longitudinal array angular motion relative to the signal source and by phase tracking the signal during the relative movement. To determine the true signal position, (2n) different software solutions for signal position are set up to process the 2n different angular data produced by each phase measurement ( phi ). The "Lobe Tracking" procedure (there are n-number of data lobes in a (n lambda ) array) which is achieved by phase tracking provides the means of matching the n-different angular data produced by the phase measurement ( phi ) to the n-different solutions set-up. From the n-different solutions set-up for signal position, only one will converge to the true signal position and the rest will diverge. The convergence or divergence depends on matching the vehicles position translation to the angular position change relative to the signal source. The solution elimination process is set up by certain solution conveyance criteria. Also the elimination process is enhanced by solution rejection based on unacceptability of angular data or lobe. Since lobe tracking matches the angular data produced by the measurement to the solution, unacceptability of data constitutes rejection of the solution.
Inventors
- 👤 Panajiotis S. Pentheroudakis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:17
CPC Classifications
G; G01; G01S; G01S3/00; G01S3/02; G01S3/14; G01S3/46; G01S3/48
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
209 words
A process of resolving the ambiguity inherent in the use of target-finding systems employing a target signal-receiving antenna array coupled to a phase meter, said array being a multi-lambda array characterized by the use of at least one pair of antennas having a baseline spacing substantially greater than the wave length of the target signal, the process comprising the steps of: establishing theoretically predetermined date relative to the rate at which the phase difference between the antennas of the multi-lambda array varies with a monotonic 360° azimuthal variation in the relative positions of said array and said target, said predetermination inherently provided a plurality of rate of exchange lobes each defining a variation in phase difference between 360° and 0° with each lobe demonstrating an abrupt 360° phase difference discontinuity transition to its next successive lobe, monotonically varying the angular attitude of said array baseline relative to said target, phase tracking said target-signal during a known incremental portion of said angular attitude variation to provide measured phase difference data as well as phase rate-of-change data and lobe discontinuity data, and matching said provided data with said predetermined data, the true bearing of the target signal being determined by degree of consistency between the provided data and the predetermined data.
Claim 2
Dependent Claim
209 words
A process of resolving the ambiguity inherent in the use of target-finding systems employing a target signal-receiving antenna array coupled to a phase meter, said array being a multi-lambda array characterized by the use of at least one pair of antennas having a baseline spacing substantially greater than the wave length of the target signal, the process comprising the steps of: establishing theoretically predetermined date relative to the rate at which the phase difference between the antennas of the multi-lambda array varies with a monotonic 360° azimuthal variation in the relative positions of said array and said target, said predetermination inherently provided a plurality of rate of exchange lobes each defining a variation in phase difference between 360° and 0° with each lobe demonstrating an abrupt 360° phase difference discontinuity transition to its next successive lobe, monotonically varying the angular attitude of said array baseline relative to said target, phase tracking said target-signal during a known incremental portion of said angular attitude variation to provide measured phase difference data as well as phase rate-of-change data and lobe discontinuity data, and matching said provided data with said predetermined data, the true bearing of the target signal being determined by degree of consistency between the provided data and the predetermined data.
Claim 3
Dependent Claim
37 words
The process of claim 1 wherein said phase tracking is applied to chronologically-successive increments of said attitude variations and said phase difference data provides measurements of the increase and decrease of the phase difference for each increment.
Claim 4
Dependent Claim
44 words
The process of claim 2 further including the steps of: computing all possible angular bearings of said target signal indicated by said provided data, said bearing computations including said lobe discontinuity data for the purpose of maintaining chronologically sequential consistency between said bearing computations.
Claim 5
Dependent Claim
99 words
The process of claim 3 wherein said means for computing said possible bearings employs a plurality of solutions each based upon the following equation: ##EQU25## where: A is a possible bearing angle of the target φ is a phase measurement k is an integer relating each phase measurement to the possible angular bearings of the target signal, said k having values of k o , ± 1, ±2, ±(n -1) n is the factor by which the baseline length of the array exceeds the wavelength of the received signal and a is an integer representing said lobe discontinuity data.
Claim 6
Dependent Claim
33 words
The process of claim 4 wherein said lobe discontinuity data (a) is an integer designating the number of lobe changes occuring during the incremental variation of the target signal and array relative positions.
Claim 7
Dependent Claim
29 words
The process of claim 5 wherein said phase tracking data is provided iteratively and with sufficient frequency to statistically substantiate the consistency between true bearing and the predetermined bearing.
Claim 8
Dependent Claim
47 words
The process of claim 1 wherein said monotonic variation is accomplished by a relative rotational movement between the array and the target signal, the azimuthal changes produced by said movement being iteratively measured for enabling a determination of the phase rate of change based upon measured data.
Claim 9
Dependent Claim
70 words
The process of claim 7 wherein said true bearing is resolved by a rotational movement of no less than 180° and by resolving the relationship -n≦a+k≦n-1 where: n is the factor by which the baseline array exceeds the wavelength of the received signal, a is an integer representing said lobe discontinuity data, and k is an integer relating each phase measurement to the possible angular bearings of the target signal.
Claim 10
Dependent Claim
36 words
The process of claim 7 wherein right-left aspects of the target are determined by the comparing of the direction of the rotational movement and the manner in which the phase measurements change during the rotational movement.
Claim 11
Dependent Claim
111 words
The process of claim 7 wherein the true bearing is resolved by a rotational movement less than 180° and by comparing the measured phase rate of change with the theoretical phase rate of change provided by the relationship; ##EQU26## where: A is a possible bearing angle of the target φ is a phase measurement, k is an integer relating each phase measurement to the possible angular bearings of the target signal, said k having values of k o , 1, 2, (n-1) n is the factor by which the baseline length of the array exceeds the wavelength of the received signal and a is an integer representing said lobe discontinuity data.
References Cited (Backward Citations)
US3120000A
Cited
US3500414A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1979-01-26 | 1979-07-28 | 1980-01-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-26 | 1983-07-28 | 1984-01-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-26 | 1987-07-28 | 1988-01-27 | $7700.00 | Window Closed / Lapsed |