Positioning method and apparatus

• US 20070184783A1
• Filed: 11/26/2004
• Published: 08/09/2007
• Est. Priority Date: 11/29/2003
• Status: Active Grant

• Current Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Original Assignee: Koninklijke Philips Electronics N.V. (Koninklijke Philips N.V.)
• Inventors: Rosenfeld, Josi
• Granted Patent: US 8,626,183 B2
• Time in Patent Office: Days
• US Class Current: 455/67.110
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: G01S 5/0244 Accuracy or reliability of position solution or of measurements contributing thereto
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

In a GPS or GSM system using DSSS signals, accurate and robust time-of-flight signal processing is achieved by selection of leading-edge or correlation techniques based on a variety of tests and environmental conditions.

Claims

1. Positioning method for a radio system, the method comprising:

receiving signals at a unit of the system;

applying at least one test on the received signals to select a processing operation on the signals, the operation being one of the following;

a correlation processing operation (Step 9, 12), a leading edge processing operation (Step 10); and

then effecting the operation selected.

2. The method of claim 1 wherein the test applied comprises determining whether the signal level of the received signal is above a threshold value (Step 4).

3. The method of claim 2 wherein, if the level of the received signal is below the threshold value, the correlation processing operation is selected (Step 12).

4. The method of claim 2 comprising, if the level of received signal is above the threshold value, testing if the leading edge gradient is above a gradient threshold value (Step 6).

5. The method of claim 3 wherein, if the leading edge gradient is below the gradient threshold value, the leading edge processing operation is selected (Step 10).

6. The method of claim 4 wherein, if the leading edge gradient is above the gradient threshold value, the correlation processing operation is selected (Step 9).

7. The method of claim 1, comprising repeating the test application and operation steps at predetermined intervals.

8. The method of claim 1 comprising coherently superposing received pulses before the test application step.

9. The method of claim 1 comprising convolution of a pulse with a bump function.

10. The method of claim 1, if the signal level is below the signal level threshold, extending the receiving time period for the signal before the next/successive test application(s).

11. The method of claim 1 comprising, before testing whether the leading edge gradient is above a threshold value, reducing the next transmit period (Step 13).

12. The method according to claim 1 comprising reducing the time period for the leading edge test for operation in a power-saving mode.

13. The method according to claim 1 comprising effecting the leading edge processing operation after selection with no intermediate testing or processing.

14. The method according to claim 1 comprising measuring the gradient using the formula:

$i=\frac{\mathrm{Cdv}}{\mathrm{Dt}}$

Where V=voltage of the signal waveform,

C=capacitance,

i=current.

15. The method according to claim 1 wherein the leading edge processing operation comprises differentiating the received signal voltage or peak and locating the zero-crossing (point of inflexion).

16. A computer program product directly loadable into the internal memory of a digital computer, comprising software code portions for performing the method of claim 1 when said product is run on a computer.

17. A computer program directly loadable into the internal memory of a digital computer, comprising software code portions for performing the method of claim 1 when said program is run on a computer.

18. A carrier, which may comprise electronic signals, for a computer program of claim 17.

19. Electronic distribution of a computer program product of claim 16.

20. Positioning apparatus for a radio system, the apparatus comprising:

means to receive signals at a unit of the system;

means (20, 21, 22) to apply at least one test on the received signals to select a processing operation on the signals which is one of the following;

a correlation processing operation, a leading edge processing operation; and

means to effect the operation selected.

21. Apparatus of claim 20 comprising means (26) to determine whether the signal level of the received signal is above a threshold value.

22. Apparatus of claim 21 comprising means (26) to select the correlation processing operation if the level of the received signal is below the threshold value.

23. Apparatus of claim 22 comprising means (26) to test whether the leading edge gradient is above a gradient threshold value, if the level of the received signal is above the threshold value.

24. Apparatus of claim 22 comprising means (27) to select the leading edge processing operation, if the leading edge gradient is below the gradient threshold value.

25. Apparatus of claim 23 comprising means (27) to select the correlation processing operation, if the leading edge gradient is above the gradient threshold value.

26. Apparatus of any of claim 20, comprising means to repeat the test application and operation steps at predetermined intervals.