APPARATUS AND METHOD FOR DERIVING POSITION INFORMATION

• US 20090239548A1
• Filed: 11/07/2005
• Published: 09/24/2009
• Est. Priority Date: 11/18/2004
• Status: Active Grant

• Current Assignee: STMicroelectronics International N.V. (STMicroelectronics NV)
• Original Assignee: ST-Ericcson SA (Telefonaktiebolaget LM Ericsson)
• Inventors: Moridi, Said, Spencer, Adrian G.
• Granted Patent: US 8,489,123 B2
• Time in Patent Office: Days
• US Class Current: 455/456.100
• CPC Class Codes: G01S 19/21 Interference related issues ; Issues related to cross-correlation, spoofing or other methods of denial of service
• CPC Class Codes: G01S 5/0218 Multipath in signal reception

Abstract

A wireless receiver for receiving signals from a satellite positioning system, and receiving signals from a communications system uses a common path in the receiver, and derives position information (60, 230) from the received signals by correlation (50, 210, 220) with a code. In a first mode the deriving is carried out from the received signals excluding selected signals received in time slots used for communications signals. A second mode includes such signals. This enables control of the trade off between accuracy and the latency of the positioning processor to improve the performance over a range of conditions. The mode input can be changed dynamically according to signal strength, or according to the needs of an application.

Claims

1. Apparatus for use in a wireless receiver for receiving signals from a positioning system, and receiving signals from a communications system using a common path in the receiver, the apparatus comprising a position processor arranged to derive position information from the received signals, the position processor having a first mode in which the deriving is carried out from the received signals excluding selected signals received in time slots being used for communications signals, and a second mode including such signals, the mode being controlled according to a mode input.

2. The apparatus of claim 1 having a means for deriving the mode input according to a characteristic of the received signals of the positioning system.

3. The apparatus of claim 2, the means for deriving the mode input comprising a comparator for comparing the signal characteristic to a threshold.

4. The apparatus of claim 1, having an input from a higher level application which uses the position information, and means for deriving the mode input according to this application input.

5. The apparatus of claim 4, the means for deriving the mode input being arranged to alter the mode input dynamically.

6. The apparatus of claim 1, the position processor comprising a correlator for correlating the received signal with a predetermined sequence to determine a transmission delay of the received signals.

7. The apparatus of claim 6 when dependent on claim 2 or 3, the position processor comprising a means for determining the signal characteristic from an output of the correlator.

8. The apparatus of claim 6, arranged to change the mode by controlling the correlator according to the mode input.

9. The apparatus of claim 6, the positioning processor being arranged to determine an average of more than one correlation output, from signals received in non-consecutive time slots, and to determine a distance value from the average.

10. The apparatus of claim 1, the communications system comprising a time division multiplex system, the means for deriving the mode input being synchronised to time slots of the communications system.

11. The apparatus of claim 1, the positioning system being satellite based.

12. The apparatus of claim 1, the position processor being arranged to store received signals for post processing.

13. The apparatus of claim 1 being implemented as one or more integrated circuits.

14. A wireless transceiver comprising an antenna, a shared RF path and the apparatus of claim 1.

15. The transceiver of claim 14 having a second antenna, separate RF paths for the communications signals and for the position system signals and a combiner for combining them onto the shared path.

16. A mobile battery powered device having the wireless transceiver of claim 14.

17. A method of using a wireless receiver to receive signals from a positioning system, and to receive signals from a communications system, comprising deriving position information from the received signals, using a first mode in which the deriving is carried out from the received signals excluding selected signals received in time slots being used for communications signals, and using a second mode including such signals, the mode being controlled according to a mode input.