Vehicle location system
First Claim
1. 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 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 receiving means for determining the position of the vehicle at the time when the vehicle mounted equipment received the GPS signals.
6 Assignments
0 Petitions
Accused Products
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). The base station also receives signals directly from the NAVSTAR GPS satellites using a second receiver (38). A control and calculating apparatus (37) within the base station can determine the ephemeris (course) information for the satellites and can measure the transmission times or propagation delays of signals between the satellites and the vehicle and with this information the control and calculating apparatus can calculate the position of the vehicle unit.
331 Citations
15 Claims
- 1. 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 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 receiving means for determining the position of the vehicle at the time when the vehicle mounted equipment received the GPS signals.
Specification