EP0303371B1
Expired / Lapsed
EP
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Navigation and tracking system
Assignee: Cambridge Positioning Systems Ltd
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Filing: 1988-07-28
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Granted: 1993-03-10
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Expires: 2008-07-28
Abstract
No abstract record available.
Inventors
- 👤 Peter James DUFFET-SMITH
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 05:29
CPC Classifications
G; G01; G01S; G01S5/00; G01S5/02; G01S5/14; G01S5/0009; G01S5/10; G01S5/145
Claims Analysis
Total Claims: 19
Claim 1
Independent Claim
203 words
A navigation and tracking system, for receiving the signals transmitted by a number of transmission sources (A,B,C) equal at least to the number of dimensions in which the movement of a roving object is to be monitored, the system comprising a pair of receiving stations (D,E), in use the first of the receiving stations (D) being at a known position and the second (E) being located on the roving object; means (F) for passing a link signal from one of the receiving stations to the other receiving station, the link signal containing information about the transmitted signals received at the one receiving station from which the phase difference or time delay between the respective signals received from the transmission sources at the receiving stations may be determined; means (R,S,T,U) at the other receiving station for comparing the information received from the one receiving station with information about the respective signals received directly from the respective transmission sources and for determining the phase difference or time delay between the respective transmitted signals received at both receiving stations and hence the change in phase difference or time delay of the signals, in order to determine the change in position or position of the roving object.
Claim 2
Dependent Claim
28 words
A system according to claim 1, further including a number of transmission sources equal at least to the number of dimensions in which movement is to be monitored.
Claim 3
Dependent Claim
30 words
A system according to claim 2, further including a number of transmission sources equal at least to the number of dimensions in which movement is to be monitored plus one.
Claim 4
Dependent Claim
21 words
A system according to claim 2 or claim 3, wherein the transmission signals are modulated and the phase difference is determined.
Claim 5
Dependent Claim
25 words
A system according to claim 2 or claim 3, wherein the transmission signals are continuous wave, unmodulated transmission signals and the phase difference is determined.
Claim 6
Dependent Claim
21 words
A system according to claim 2 or claim 3, wherein the transmission signals are modulated and the timing delays are determined.
Claim 7
Dependent Claim
18 words
A system according to claim 2 or claim 3, wherein both phase difference and timing delays are determined.
Claim 8
Dependent Claim
52 words
A system according to claim 4 or claim 5, wherein the receiving stations convert the signals received to baseband signals by the use of local oscillators which are phase-locked to local frequency standards or reference oscillators (K,L) and the baseband signal from one of the receiving stations is transmitted to the other.
Claim 9
Dependent Claim
26 words
A system according to claim 8, further including an additional transmission source (C) for measuring the drift of the reference oscillators or frequency standards (K, L).
Claim 10
Dependent Claim
24 words
A system according to claim 8, wherein the reference oscillators (K,L) are locked to one another using the transmission link between the receiving stations.
Claim 11
Independent Claim
29 words
A system according to any of the preceding claims, wherein a non-roving receiving station called a base station is located at the same location as one of the transmitters.
Claim 12
Dependent Claim
22 words
A system according to claim 11, wherein the link is provided in the direction from the base station to the roving object.
Claim 13
Dependent Claim
29 words
A system according to claim 12, wherein the base station has an omni-directional radiation pattern, whereby any number of separate roving objects can navigate using the same link signals.
Claim 14
Dependent Claim
34 words
A system according to claim 2 or any claim when dependent thereon, wherein the transmission signals from at least one of the transmission sources are used to provide the link between the receiving stations.
Claim 15
Dependent Claim
21 words
A system according to claim 11, wherein the same reference oscillator is used for the transmitter source and co-located receiving station.
Claim 16
Dependent Claim
43 words
A system according to claim 6, wherein the means for comparing the signals received by the plural receiving stations includes means (a,b,b') for digitizing the converted signals and means (X) for correlating the digitized signals to produce point estimates of the cross-correlation function.
Claim 17
Dependent Claim
28 words
A system according to claim 16, wherein an interpolation function is fitted to the point estimates of the cross-correlation function to determine the time delay between the signals.
Claim 18
Independent Claim
30 words
A system according to any of claims 1 to 17, wherein the signals received by each receiving station are mixed by multiplication with a signal from a respective local oscillator.
Claim 19
Dependent Claim
83 words
A system according to claim 1, wherein each receiving station (D,E) has a reference oscillator, and which includes means for deriving from the reference oscillator a local reference signal; and means for generating a signal representative of the difference in frequency and hence the difference in phase between the local reference signal and the signal received from each of the transmission sources, said representative signal generated within one of the receiving stations being passed as the link signal to the other receiving station.
References Cited (Backward Citations)
No citation records indexed.
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