US3829674A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Slow modulation distance measuring apparatus
Assignee: United States Department of the Navy
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Filing: 1973-01-26
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Granted: 1974-08-13
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Expires: 1993-01-26
Abstract
Abstract Apparatus for locating a source of slow modulation or intermittent, radiant energy. Transmitted signals are received by a pair of separated, remote receiver stations and at a local station. The signals received at the remote stations are relayed to the local station where each signal is recorded on a separate track after each is normalized to the same average amplitude. The recorded signals are played back on apparatus having a movable head which can be positioned relative to a stationary head while at the same time permitting both to follow high-speed paths at the same angular velocity except for the phase angle difference. The movable head plays back the signal from one of the remote stations and the stationary head plays back the signal from the local station. The instantaneous amplitudes of the two signals are superimposed on each other and multiplied together to form an autocorrelation function. The process is repeated with a different position of the movable head until the average product reaches a maximum value. The maximum value is compared with the square of one of the signal amplitudes averaged over the same time interval, and if the maximum and square are substantially equal the unique correlation is reached when the difference in head position measures the time delay. If a satisfactory match is not obtained, a new area of the recorded signal is searched.
Inventors
- 👤 H Joseph
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 18:20
CPC Classifications
G; G06; G06G; G06G7/00; G06G7/12; G06G7/19; G06G7/1914; G01; G01S; G01S5/00; G01S5/02; G01S5/06
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
385 words
A transmitter location system comprising: receiver apparatus for receiving signals S1, S2, and S3, transmitted by an unknown transmitter, and wherein S1 and S2 are relayed from known transmitters to the said receiver apparatus and wherein S3 is transmitted directly to said receiver apparatus from said unknown transmitter; first and second clock counter means connected to the output of said receiver means for measuring the relative elapsed times between receipt of S3 and S1, and S3 and S2, and for producing clock counts, t1 and t2, corresponding to said elapsed times, respectively; video recorder apparaus connected to the output of said receiver and said clock means and comprising four circular recorder heads mounted in a fixed, concentric manner with respect to each other for recording said received signals S1, S2, and S3, upon magnetic tape, tape movement means adapted to move said tape under said tape under said recorder heads, said recorder head being adapted to move over said tape in a circular and counterclockwise manner, four circular playback heads mounted on the same plane as said recorder heads and in a concentric manner with respect to each other and without said recorder heads, and further adapted to move over said tape in a circular and clockwise manner, two of said playback heads being independently rotatable with respect to the other two of said playback heads and being adapted to play back S1 and S2, respectively, ratchet mechanism means coupled to said tape movement means and connected to the output of said clock means to inhibit motion of said tape in response to said clock counts t1 and t2 signals produced by said clock means indicating that S1, S2, and S3, have been received; servo means connected to the outputs of said two movable playback heads and including means for multiplying each of the signals S1 and S2 recorded thereon with a reference signal to produce first and second control signals proportional to the corresponding maximum values of said multiplication, and, planetary gear means coupled to said two movable playback heads and being connected to the output of said servo means and being responsive to said first and second control signals to rotate said movable heads with respect to the other two playback heads an angular distance corresponding to said clock counts t1 and t2.
Claim 2
Dependent Claim
385 words
A transmitter location system comprising: receiver apparatus for receiving signals S1, S2, and S3, transmitted by an unknown transmitter, and wherein S1 and S2 are relayed from known transmitters to the said receiver apparatus and wherein S3 is transmitted directly to said receiver apparatus from said unknown transmitter; first and second clock counter means connected to the output of said receiver means for measuring the relative elapsed times between receipt of S3 and S1, and S3 and S2, and for producing clock counts, t1 and t2, corresponding to said elapsed times, respectively; video recorder apparaus connected to the output of said receiver and said clock means and comprising four circular recorder heads mounted in a fixed, concentric manner with respect to each other for recording said received signals S1, S2, and S3, upon magnetic tape, tape movement means adapted to move said tape under said tape under said recorder heads, said recorder head being adapted to move over said tape in a circular and counterclockwise manner, four circular playback heads mounted on the same plane as said recorder heads and in a concentric manner with respect to each other and without said recorder heads, and further adapted to move over said tape in a circular and clockwise manner, two of said playback heads being independently rotatable with respect to the other two of said playback heads and being adapted to play back S1 and S2, respectively, ratchet mechanism means coupled to said tape movement means and connected to the output of said clock means to inhibit motion of said tape in response to said clock counts t1 and t2 signals produced by said clock means indicating that S1, S2, and S3, have been received; servo means connected to the outputs of said two movable playback heads and including means for multiplying each of the signals S1 and S2 recorded thereon with a reference signal to produce first and second control signals proportional to the corresponding maximum values of said multiplication, and, planetary gear means coupled to said two movable playback heads and being connected to the output of said servo means and being responsive to said first and second control signals to rotate said movable heads with respect to the other two playback heads an angular distance corresponding to said clock counts t1 and t2.
Claim 3
Dependent Claim
21 words
The system of claim 1 wherein said servo means further includes integrator means connected to the output of said multiplier means.
Claim 4
Dependent Claim
21 words
The system of claim 1 wherein said recorder apparatus further includes means for measuring said angular rotation of said rotatable heads.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-12 | 1978-02-11 | 1978-08-13 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-12 | 1982-02-11 | 1982-08-13 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-12 | 1986-02-11 | 1986-08-13 | $7700.00 | Window Closed / Lapsed |