US4486862A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Determination of system response
Assignee: Department of Industry, Science and Resources
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Filing: 1982-08-19
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Granted: 1984-12-04
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Expires: 2002-08-19
Abstract
Abstract Determination of the impulse response of a system such as a hydrophone is determined by generating a broad band reproducible test signal which after propagation is received and a replica of the broad band test signal is produced; either the received signal is compensated for fluctuations in propagation time of the test signal through the system and cross correlation of the compensated signal with the non-compensated signal is effected to derive the system response. A secondary signal may be used with the broad band test signal whereby the Doppler shift of the secondary signal can be utilized to determine the required compensation. Feed-back shift registers are disclosed for generating pseudo random noise for the test signal and the replica thereof. The invention permits calibration of a hydrophone in circumstances in which noise is present and variation in path length of the propagated test signal occurs.
Inventors
- 👤 Ronald J. Wyber
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 09:36
CPC Classifications
G; G01; G01V; G01V13/00; G01H; G01H3/00; G01H3/005
Claims Analysis
Total Claims: 26
Claim 1
Independent Claim
125 words
A method of determining the system response for a system where there is noise present and the propagation time of a signal used to test the system response is subject to variation, the method comprising the steps of: (a) generating a broad band reproducible test signal and applying it to the system for propagation therethrough; (b) detecting the signal after it has been passed by the system; (c) producing a replica of the test signal; (d) applying compensation to either the detected signal or the replica signal to compensate for fluctuations in propagation time of the test signal through the system, and (e) cross correlating the compensated signal with the noncompensated one of the detected and replica signals in order to derive the system response.
Claim 2
Independent Claim
125 words
A method of determining the system response for a system where there is noise present and the propagation time of a signal used to test the system response is subject to variation, the method comprising the steps of: (a) generating a broad band reproducible test signal and applying it to the system for propagation therethrough; (b) detecting the signal after it has been passed by the system; (c) producing a replica of the test signal; (d) applying compensation to either the detected signal or the replica signal to compensate for fluctuations in propagation time of the test signal through the system, and (e) cross correlating the compensated signal with the noncompensated one of the detected and replica signals in order to derive the system response.
Claim 3
Dependent Claim
18 words
A method according to claim 1, wherein the compensation is applied to the replica of the test signal.
Claim 4
Dependent Claim
27 words
A method according to claim 1, wherein the function produced by cross correlating is recorded and subsequently a Fourier transform is made to analyse the system response.
Claim 5
Dependent Claim
38 words
A method according to claim 1 and wherein in addition to said broad band test signal, a secondary signal is generated and detected and the Doppler shift of said secondary signal is utilised for determining the required compensation.
Claim 6
Dependent Claim
16 words
A method as defined in claim 4, wherein said secondary signal is a single tone signal.
Claim 7
Dependent Claim
57 words
A method as defined in claim 1 wherein the broad band test signal is produced in the form of pseudo random noise by a feedback shift register and said replica of the test signal is produced by a similar feedback shift register, and the method including generating a synchronising pulse to sychronise sequences of said feedback registers.
Claim 8
Dependent Claim
36 words
A method as claimed in claim 1 and further comprising recording signals from said cross correalation step and applying a gating window technique to gate-out the signal components due to secondary reflected signals in the system.
Claim 9
Dependent Claim
110 words
Apparatus for use in testing the system response of a system in which the propagation time of a broad band test signal applied to the system for this purpose is subject to variation, the apparatus comprising means for receiving the propagated broad band test signal, means to replicate the applied broad band signal, means for determining the required compensation for fluctuations in the propagation time of the test signal through the system, means for compensating the replica signal to compensate for fluctuations in propagation time of the test signal, and output means for providing signals for cross-correlation, the signals being the compensated replicated signal and the broad band test signal.
Claim 10
Dependent Claim
110 words
Apparatus for use in testing the system response of a system in which the propagation time of a broad band test signal applied to the system for this purpose is subject to variation, the apparatus comprising means for receiving the propagated broad band test signal, means to replicate the applied broad band signal, means for determining the required compensation for fluctuations in the propagation time of the test signal through the system, means for compensating the replica signal to compensate for fluctuations in propagation time of the test signal, and output means for providing signals for cross-correlation, the signals being the compensated replicated signal and the broad band test signal.
Claim 11
Dependent Claim
30 words
An apparatus as claimed in claim 8 and including means for cross-correlating said output signals thereby providing a cross-correlation function which is capable of analysis by a Fourier transform technique.
Claim 12
Dependent Claim
17 words
Apparatus as claimed in claim 8 in combination with means for generating said broad band test signal.
Claim 13
Dependent Claim
33 words
An apparatus as claimed in claim 10, wherein said generating means comprises a feedback shift register for generating pseudo random white noise, an identical feedback shift register being provided for said replicating means.
Claim 14
Dependent Claim
34 words
An apparatus as claimed in claim 11, and wherein said compensation means comprises means for modifying a clock drive of the feedback shift register to be associated with the receiving portion of the system.
Claim 15
Dependent Claim
54 words
An apparatus as claimed in claim 12, wherein said means for modifying includes means for transmitting a second test signal simultaneously with said broad band test signal, and means for detecting second test signal changes in propagation time, the second signal being a single tone signal whereby the propagation time introduces a Doppler shift.
Claim 16
Dependent Claim
20 words
An apparatus as claimed in claim 11 and including means for generating a synchronising pulse for the feedback shift registers.
Claim 17
Dependent Claim
27 words
An apparatus as claimed in claim 8 in combination with a signal processor arranged for effecting cross correlation of the signals and storing the cross correlation function.
Claim 18
Dependent Claim
113 words
Apparatus for use in testing the system response of a system in which the propagation time of a broad band test signal applied to the system for this purpose is subject to variation, the apparatus comprising means for receiving the propagated broad band test signal, means to replicate the applied broad band signal, means for determining the required compensation for fluctuations in the propagation time of the test signal through the system, means for compensating the received broad band test signal to compensate for fluctuations in propagation time of the test signal, and output means for providing signals for cross-correlation, the signals being the replicated signal and compensated received broad band test signal.
Claim 19
Dependent Claim
113 words
Apparatus for use in testing the system response of a system in which the propagation time of a broad band test signal applied to the system for this purpose is subject to variation, the apparatus comprising means for receiving the propagated broad band test signal, means to replicate the applied broad band signal, means for determining the required compensation for fluctuations in the propagation time of the test signal through the system, means for compensating the received broad band test signal to compensate for fluctuations in propagation time of the test signal, and output means for providing signals for cross-correlation, the signals being the replicated signal and compensated received broad band test signal.
Claim 20
Dependent Claim
30 words
An apparatus as claimed in claim 16 and including means for cross-correlating said output signals thereby providing a cross-correlation function which is capable of analysis by a Fourier transform technique.
Claim 21
Dependent Claim
17 words
Apparatus as claimed in claim 16 in combination with means for generating said broad band test signal.
Claim 22
Dependent Claim
33 words
An apparatus as claimed in claim 18, wherein said generating means comprises a feedback shift register for generating pseudo random white noise, an identical feedback shift register being provided for said replicating means.
Claim 23
Dependent Claim
34 words
An apparatus as claimed in claim 19, and wherein said compensation means comprises means for modifying a clock drive of the feedback shift register to be associated with the receiving portion of the system.
Claim 24
Dependent Claim
54 words
An apparatus as claimed in claim 20, wherein said means for modifying includes means for transmitting a second test signal simultaneously with said broad band test signal, and means for detecting second test signal changes in propagation time, the second signal being a single tone signal whereby the propagation time introduces a Doppler shift.
Claim 25
Dependent Claim
20 words
An apparatus as claimed in claim 19 and including means for generating a synchronising pulse for the feedback shift registers.
Claim 26
Dependent Claim
27 words
An apparatus as claimed in claim 16 in combination with a signal processor arranged for effecting cross correlation of the signals and storing the cross correlation function.
References Cited (Backward Citations)
US3912880A
Cited
US3942150A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-12-04 | 1988-06-04 | 1988-12-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-04 | 1992-06-04 | 1992-12-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-04 | 1996-06-04 | 1996-12-04 | $7700.00 | Window Closed / Lapsed |