EP0444738A2
Expired / Lapsed
EP
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Vehicle location system
Assignee: Philips Electronics UK Ltd
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Filing: 1991-02-20
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Granted: —
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Expires: 2011-02-20
Abstract
Abstract Signals from a number of NAVSTAR global positioning system (GPS) satellites (11,12,13,14) are received by a receiver (16) in a vehicle (15) and a segment of the signals is stored in a memory (18) prior to retransmission by a transmitter (19). A base station (35) receives these transmissions from the mobile unit using a first receiver (36) as well as receiving signals directly from the NAVSTAR GPS satellites (11,12,13,14) using a second receiver (38). A control and calculating means (37) within the base station (35) can determine the ephemeris (course) information for the satellites and measure the transmission times or propagation delays of signals between the satellites and the vehicle and with this information the control and calculating means (37) can calculate the position of the vehicle unit.
Inventors
- 👤 Michael Edwin Barnard
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 03:13
CPC Classifications
G; G01; G01S; G01S5/00; G01S5/0009; G01S5/0018; G01S5/0036; G01S19/00; G01S19/01; G01S19/03; G01S19/09; G01S19/38; G01S19/39; G01S19/40; G01S19/41
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
127 words
A vehicle location system for use in a global positioning system (GPS), comprising at least one vehicle mounted equipment including means for receiving signals directly from the GPS, a fixedly sited base station including first means for receiving signals directly from the GPS, characterised in that the or each vehicle mounted equipment includes means for recording the received GPS signals and means for retransmitting the recorded GPS signals to the base station, and in that the fixedly sited base station includes second means for receiving the recorded GPS signals retransmitted by the vehicle mounted equipment, and position determining means coupled to the first and second means, for determining the position of the or each vehicle at the time when the vehicle mounted equipment received the GPS signals.
Claim 2
Dependent Claim
31 words
A vehicle location system as claimed in Claim 1, characterised in that the vehicle mounted equipment transmits a time of arrival (TOA) signal in addition to retransmitting the recorded GPS signals.
Claim 3
Dependent Claim
37 words
A vehicle location system as claimed in Claim 1 or Claim 2, characterised in that the rate at which the vehicle mounted equipment retransmits the GPS signals is lower than that at which the signals were recorded.
Claim 4
Dependent Claim
49 words
A vehicle location system as claimed in Claim 1, Claim 2 or Claim 3, characterised in that the vehicle mounted equipment further comprises control means coupled to the recording means, and in that signals from the control means cause the recording means to record GPS signals at preset intervals.
Claim 5
Dependent Claim
45 words
A vehicle location system as claimed in any one of the Claims 1 to 4, characterised in that the GPS is the satellite-based NAVSTAR GPS, and in that the or each base station has means for obtaining the GPS ephemeris for the satellites in use.
Claim 6
Dependent Claim
42 words
A vehicle location system as claimed in Claim 5, characterised in that the means for obtaining the GPS ephemeris in the or each base station has means for despreading the NAVSTAR GPS signals without using any locally generated pseudo random noise codes.
Claim 7
Dependent Claim
48 words
A vehicle mounted equipment for use with the system as claimed in any one of the Claims 1 to 6, including means for receiving GPS signals, characterised in that the equipment also includes means for recording the received GPS signals and means for retransmitting the recorded GPS signals.
Claim 8
Dependent Claim
53 words
A vehicle mounted equipment for use with the system as claimed in Claim 2 or any Claim dependent thereon, including means for receiving GPS signals, characterised in that the equipment includes means for recording the received GPS signals and means for retransmitting the recorded GPS signals and a time of arrival (TOA) signal.
Claim 9
Dependent Claim
81 words
A fixedly sited base station for use with the system as claimed in any one of the Claims 1 to 6, including first means for receiving GPS signals directly from the GPS, characterised in that the base station also includes second means for receiving a retransmission of GPS signals from a vehicle mounted equipment and means coupled to said first and second means for determining the position of the vehicle mounted equipment at the time that the GPS signals were received.
Claim 10
Dependent Claim
48 words
A fixedly sited base station as claimed in Claim 9, characterised in that the means for determining the position of the vehicle mounted equipment calculates the position of the base station using the GPS and then calculates the position of the vehicle mounted equipment using a differential technique.
References Cited (Backward Citations)
No citation records indexed.
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