Communications: directive radio wave systems and devices (e.g. – Directive – Position indicating
Patent
1998-03-17
2000-07-25
Blum, Theodore M.
Communications: directive radio wave systems and devices (e.g.,
Directive
Position indicating
342464, 342457, 342375, H04B 7185, G01S 502
Patent
active
060941685
DESCRIPTION:
BRIEF SUMMARY
This invention relates to a position determining system using radio or other broadcast transmissions. More particularly, it relates to a system using the Global System for Mobile Communications (GSM) or other digital transmission systems.
In our European Patent EP-B-0 303 371 we describe a radio navigation and tracking system, now known as `CURSOR`, which uses the spatial coherence of the signals from several radio transmitters to determine the position of a roving receiver. Its principles are explained in the above patent specification where it is shown how the signals received directly by the roving receiver (rover) are compared with those received by a fixed base station whose location is known (base) to determine their phase difference, and hence the difference in range of the base and rover from each transmitter. Three such measurements made on independent transmitters are needed for navigation and tracking in two dimensions to fix the position of the rover relative to the base station and network of transmitters. The unknown quantities calculated for each new position are the spatial x and y co-ordinates of the rover together with the phase offset between the local oscillators in the equipment of the two receivers. A further patent specification, WO 94/28432, shows how the same principles may be applied in tunnels and other shielded spaces such as underground car parks. Duffett-Smith and Woan (Journal of Navigation, 45, 157, 1992) describe a particular implementation of the phase-measuring system in which the signals from three or more medium-wave AM public broadcast stations are used to track the position of a vehicle in and around Cambridge, UK, at speeds up to 110 km h.sup.-1, with a precision of about 5 m. One of the advantages of such a system lies in the fact that no additional costly infrastructure of coherent radio transmitters needs to be set up for CURSOR operation. On the contrary, CURSOR is able to use the signals from any independent radio transmitters set up for any purpose.
EP-B-0 303 371 also explains how the wider bandwidth signals of modulated transmissions may be used to measure the time difference between the signals received from each transmitter at the base station and the rover. In this case, the position of the peak in the cross correlation can be used as an estimator of the time difference between the two received signals, and hence the difference in distance from the transmitter of the base and rover. As with the phase-measuring system, three such measurements made on three widely-spaced transmitters suffice to calculate the spatial x and y co-ordinates of the rover together with the time offset between the oscillators in the two receiving stations.
Mobile telephones are increasingly using GSM and other digital techniques, and it would be an advantage to add time-measuring CURSOR positioning technology to provide additional services for users. However, signals radiated by digital telephone transmitters are complex and therefore there are problems to be overcome in attempting to combine the technologies.
According to the present invention there is provided a position determining system, for receiving broad band signals transmitted by a number of transmission sources equal at least to the number of dimensions in which the movement of a roving object is to be monitored, the system comprising being at a known position and the second being located on the roving object; position determining processor, the link signal containing information about the signals received at the receiving station from the transmission sources; from the respective transmission sources substantially simultaneously, and the position determining processor is arranged to compare the information received from the one receiving station about the signals received at the one receiving station from the transmission sources with the information received from the other receiving station about the signals received at the other receiving station from the transmission sources, and to determine the time delay between t
REFERENCES:
patent: 5045861 (1991-09-01), Duffett-Smith et al.
patent: 5208756 (1993-05-01), Song
patent: 5293642 (1994-03-01), Lo
patent: 5293645 (1994-03-01), Sood
patent: 5327144 (1994-07-01), Stilp et al.
patent: 5365450 (1994-11-01), Schuchman et al.
patent: 5422813 (1995-06-01), Schuchman et al.
patent: 5512909 (1996-04-01), Kronhamn
patent: 5519618 (1996-05-01), Kastner et al.
patent: 5568153 (1996-10-01), Beliveau
patent: 5600706 (1997-02-01), Dunn
patent: 5604765 (1997-02-01), Bruno et al.
patent: 5612729 (1997-03-01), Ellis et al.
patent: 5613205 (1997-03-01), Dufour
patent: 5701328 (1997-12-01), Schuchman et al.
patent: 5729694 (1998-03-01), Holzrichter et al.
patent: 5838279 (1998-11-01), Duffett-Smith et al.
P.J. Duffett-Smith and G. Woan, "The Cursor Radio Navigation and Tracking System", Journal of Navigation, vol. 45, No. 2, pp. 157-165 (1992).
Duffett-Smith Peter James
Grainge Keith James Bruno
Blum Theodore M.
Cambridge Positioning Systems Ltd.
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