US5594452A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and system for locating an unknown transmitter using calibrated oscillator phases
Assignee: TRANSMITTER LOCATING SYSTEMS LLC
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Filing: 1994-12-01
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Granted: 1997-01-14
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Expires: 2014-12-01
Abstract
Abstract In a method and system for locating an unknown transmitter which emits an interfering signal, multiple signals, including a phase-calibrating signal and the interfering signal, are simultaneously observed within a passband. These signals are then simultaneously cross-correlated. The phase-calibrating signal is then isolated from the cross-correlated signals and processed to determine an amount of offset to compensate for frequency fluctuations between local oscillators in satellites, which receive and retransmit the phase-calibrating signal and the interfering signal.
Inventors
- 👤 John C. Webber
- 👤 Curtis A. Knight
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:45
CPC Classifications
H; H04; H04B; H04B7/00; H04B7/14; H04B7/15; H04B7/204; H04B7/208; G; G01; G01S; G01S1/00; G01S1/02; G01S1/022; G01S1/026; G01S5/00; G01S5/02; G01S5/06; G01S5/12
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
115 words
A method of phase calibrating oscillators located on at least two satellites, comprising the steps of: retransmitting from the at least two satellites an interfering signal and a phase-calibrating signal; observing a band of frequencies encompassing a frequency of the interfering signal and a frequency of the phase-calibrating signal; receiving signals within the band of frequencies; simultaneously cross-correlating the received signals; isolating a portion of the cross-correlated signals corresponding to the phase-calibrating signal; determining from the isolated portion a phase function representative of at least one of phase and frequency discrepancies between oscillators located on the at least two satellites; and phase calibrating remaining portions of the cross-correlated signals in accordance with the phase function.
Claim 2
Independent Claim
115 words
A method of phase calibrating oscillators located on at least two satellites, comprising the steps of: retransmitting from the at least two satellites an interfering signal and a phase-calibrating signal; observing a band of frequencies encompassing a frequency of the interfering signal and a frequency of the phase-calibrating signal; receiving signals within the band of frequencies; simultaneously cross-correlating the received signals; isolating a portion of the cross-correlated signals corresponding to the phase-calibrating signal; determining from the isolated portion a phase function representative of at least one of phase and frequency discrepancies between oscillators located on the at least two satellites; and phase calibrating remaining portions of the cross-correlated signals in accordance with the phase function.
Claim 3
Dependent Claim
33 words
The method according to claim 1, wherein the step of phase calibrating remaining portions includes the step of subtracting the phase function from remaining portions of the cross-correlated signals on a point-by-point basis.
Claim 4
Dependent Claim
21 words
The method according to claim 1, wherein the step of isolating includes frequency filtering the cross-correlated signals in a frequency-domain function.
Claim 5
Dependent Claim
20 words
The method according to claim 1, wherein the band of frequencies are observed at two antennas located near each other.
Claim 6
Dependent Claim
25 words
The method according to claim 1, wherein the frequency of the interfering signal and the frequency of the phase-calibrating signal are different from each other.
Claim 7
Dependent Claim
21 words
The method according to claim 1, wherein the band of frequencies are observed at two antennas located remotely from each other.
Claim 8
Dependent Claim
21 words
The method according to claim 6, wherein received signals received at one antenna site are transmitted to the other antenna site.
Claim 9
Independent Claim
123 words
A method of locating an unknown transmitter emitting an interfering signal, comprising the steps of: retransmitting from at least two satellites an interfering signal and a phase-calibrating signal; observing a band of frequencies encompassing a frequency of the interfering signal and a frequency of the phase-calibrating signal; receiving signals within the band of frequencies; simultaneously cross-correlating the received signals; isolating a portion of the cross-correlated signals corresponding to the phase-calibrating signal; determining from the isolated portion a phase function representative of at least one of phase and frequency discrepancies between oscillators located on the at least two satellites; phase calibrating remaining portions of the cross-correlated signals in accordance with the phase function; and locating the unknown transmitter in accordance with the phase-calibrated portions.
Claim 10
Independent Claim
123 words
A method of locating an unknown transmitter emitting an interfering signal, comprising the steps of: retransmitting from at least two satellites an interfering signal and a phase-calibrating signal; observing a band of frequencies encompassing a frequency of the interfering signal and a frequency of the phase-calibrating signal; receiving signals within the band of frequencies; simultaneously cross-correlating the received signals; isolating a portion of the cross-correlated signals corresponding to the phase-calibrating signal; determining from the isolated portion a phase function representative of at least one of phase and frequency discrepancies between oscillators located on the at least two satellites; phase calibrating remaining portions of the cross-correlated signals in accordance with the phase function; and locating the unknown transmitter in accordance with the phase-calibrated portions.
Claim 11
Dependent Claim
73 words
The method according to claim 8, wherein the step of locating the unknown transmitter includes the steps of: isolating a portion of the phase-calibrated portions corresponding to the interfering signal; determining time difference of arrival data and frequency difference of arrival data from the isolated portion corresponding to the interfering signal; and determining a location of the unknown transmitter based upon the time difference of arrival data and frequency difference of arrival data.
Claim 12
Dependent Claim
25 words
The method according to claim 8, wherein the frequency of the interfering signal and the frequency of the phase-calibrating signal are different from each other.
Claim 13
Independent Claim
158 words
A method of phase calibrating signals to locate an unknown signal position, comprising the steps of: receiving and retransmitting, from at least two satellites, an interfering signal, a phase-calibrating signal, and at least one position-calibrating signal; observing a band of frequencies encompassing a frequency of the interfering signal, a frequency of the phase-calibrating signal, and frequencies of the at least one position-calibrating signal; receiving signals within the band of frequencies; simultaneously cross-correlating the received signals; isolating a portion of the cross-correlated signals corresponding to the phase-calibrating signal; determining from the isolated portion a phase function representative of at least one of a phase discrepancy and a frequency discrepancy between oscillators located on the at least two satellites; phase calibrating remaining portions of the cross-correlated signals for the unknown and position-calibrating signals in accordance with the phase function; and determining the unknown signal position in accordance with the phase-calibrated portion of the cross-correlated signal corresponding to the unknown signal.
Claim 14
Independent Claim
158 words
A method of phase calibrating signals to locate an unknown signal position, comprising the steps of: receiving and retransmitting, from at least two satellites, an interfering signal, a phase-calibrating signal, and at least one position-calibrating signal; observing a band of frequencies encompassing a frequency of the interfering signal, a frequency of the phase-calibrating signal, and frequencies of the at least one position-calibrating signal; receiving signals within the band of frequencies; simultaneously cross-correlating the received signals; isolating a portion of the cross-correlated signals corresponding to the phase-calibrating signal; determining from the isolated portion a phase function representative of at least one of a phase discrepancy and a frequency discrepancy between oscillators located on the at least two satellites; phase calibrating remaining portions of the cross-correlated signals for the unknown and position-calibrating signals in accordance with the phase function; and determining the unknown signal position in accordance with the phase-calibrated portion of the cross-correlated signal corresponding to the unknown signal.
Claim 15
Dependent Claim
34 words
The method according to claim 11, wherein, in the phase-calibrating step, the phase function is applied in a like manner to the portions of the cross-correlated signals corresponding to the unknown and position-calibrating signals.
Claim 16
Dependent Claim
34 words
The method according to claim 11, further comprising the step of determining positions of the at least two satellites in accordance with the phase-calibrated portion of the cross-correlated signal corresponding to the position-calibrating signal.
Claim 17
Independent Claim
87 words
A system for phase calibrating signals to locate an unknown transmitter, comprising: at least two satellites receiving and retransmitting an interfering signal and a phase-calibrating signal; at least two antennas, each antenna simultaneously receiving a band of signals from a respective satellite, the band of signals including the interfering signal and the phase-calibrating signal; means for phase calibrating the received signals; and means for locating the unknown transmitter in accordance with the phase-calibrated signals, wherein the phase-calibrating means includes means for simultaneously cross-correlating the band of signals.
Claim 18
Independent Claim
87 words
A system for phase calibrating signals to locate an unknown transmitter, comprising: at least two satellites receiving and retransmitting an interfering signal and a phase-calibrating signal; at least two antennas, each antenna simultaneously receiving a band of signals from a respective satellite, the band of signals including the interfering signal and the phase-calibrating signal; means for phase calibrating the received signals; and means for locating the unknown transmitter in accordance with the phase-calibrated signals, wherein the phase-calibrating means includes means for simultaneously cross-correlating the band of signals.
Claim 19
Dependent Claim
17 words
The system according to claim 14, wherein the at least two antennas are located near each other.
Claim 20
Dependent Claim
37 words
The system according to claim 14, wherein the at least two antennas are located remotely from each other, and further including means for transmitting the received band of signals from one antenna site to another antenna site.
Claim 21
Dependent Claim
25 words
The system according to claim 14, wherein the frequency of the interfering signal and the frequency of the phase-calibrating signal are different from each other.
Claim 22
Independent Claim
172 words
A system for phase calibrating signals to locate an unknown signal position, comprising: at least two satellites receiving and retransmitting an interfering signal, a phase-calibrating signal, and at least one position-calibrating signal; at least two antennas, each antenna simultaneously observing a band of frequencies encompassing a frequency of the interfering signal, a frequency of the phase-calibrating signal, and frequencies of the at least one position-calibrating signal, and receiving signals having frequencies within the band; means for simultaneously cross-correlating the received signals; means for isolating a portion of the cross-correlated signals corresponding to the phase-calibrating signal; means for determining from the isolated portion a phase function representative of at least one of a phase discrepancy and a frequency discrepancy between oscillators located on the at least two satellites; means for phase calibrating remaining portions of the cross-correlated signals for the unknown and position-calibrating signals in accordance with the phase function; and means for determining the unknown signal position in accordance with the phase-calibrated portion of the cross-correlated signal corresponding to the unknown signal.
Claim 23
Independent Claim
172 words
A system for phase calibrating signals to locate an unknown signal position, comprising: at least two satellites receiving and retransmitting an interfering signal, a phase-calibrating signal, and at least one position-calibrating signal; at least two antennas, each antenna simultaneously observing a band of frequencies encompassing a frequency of the interfering signal, a frequency of the phase-calibrating signal, and frequencies of the at least one position-calibrating signal, and receiving signals having frequencies within the band; means for simultaneously cross-correlating the received signals; means for isolating a portion of the cross-correlated signals corresponding to the phase-calibrating signal; means for determining from the isolated portion a phase function representative of at least one of a phase discrepancy and a frequency discrepancy between oscillators located on the at least two satellites; means for phase calibrating remaining portions of the cross-correlated signals for the unknown and position-calibrating signals in accordance with the phase function; and means for determining the unknown signal position in accordance with the phase-calibrated portion of the cross-correlated signal corresponding to the unknown signal.
Claim 24
Dependent Claim
32 words
The method according to claim 18, wherein the phase-calibrating means applies the phase function in a like manner to the portions of the cross-correlated signals corresonding to the unknown and position-calibrating signals.
Claim 25
Dependent Claim
33 words
The method according to claim 18, further comprising means for determining positions of the at least two satellites in accordance with the phase-calibrated portion of the cross-correlated signal corresponding to the position-calibrating signal.
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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) | 2000-01-14 | 2000-07-15 | 2001-01-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-01-14 | 2004-07-15 | 2005-01-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-01-14 | 2008-07-15 | 2009-01-14 | $7700.00 | Window Closed / Lapsed |