Method of, and apparatus for, determining position

• US 20050140547A1
• Filed: 02/07/2003
• Published: 06/30/2005
• Est. Priority Date: 03/22/2002
• Status: Abandoned Application

• 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
• Application Number:
  US10/508,285
• Publication Number:
  US 20050140547A1
• Time in Patent Office: Days
• US Class Current: 342/417
• CPC Class Codes: G01S 11/08 using synchronised clocks
• CPC Class Codes: G01S 5/0218 Multipath in signal reception
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

A method of, and apparatus for, determining position, comprises a receiver (14) receiving a signal from a remote transmitter (22) whose position has to be determined. The Fourier transform of a power spectrum density of the received signal is determined and a check is made to see if a line-of-sight (LOS) signal is present. If so, a multipath mitigation technique is implemented to identify the LOS signal and once identified the position of the remote transmitter is determined by deriving the propagation time of the LOS signal. Current can be saved by inhibiting the multipath mitigation technique in the absence of detecting a LOS signal. In one embodiment the presence or absence of the LOS signal is determined by dividing the magnitude of the peak at zero frequency by the maximum magnitude of all the other peaks and if the answer is less than unity, LOS is not present.

Claims

1. A method of determining position, comprising receiving a signal from a remote transmitter, determining if a line-of-sight (LOS) signal is present and determining the position of the remote transmitter using the LOS signal.

2. A method as claimed in claim 1, characterised by deriving the Fourier transform of a power spectrum density of the received signal, checking for the presence of a DC value at zero frequency, if so, implementing a multipath mitigation technique to identify the LOS signal.

3. A method as claimed in claim 2, characterised by responding to is the absence of the LOS signal by inhibiting the multipath mitigation technique.

4. A method as claimed in claim 1, characterised by deriving the Fourier transform of a power spectrum density of the received signal and by determining the presence or absence of the LOS signal by dividing the magnitude of the peak at zero frequency by the maximum magnitude of all the other peaks and if the answer is less than unity, LOS is not present.

5. A method as claimed in claim 1, characterised by deriving the Fourier transform of a power spectrum density of the received signal and by determining the presence or absence of the LOS signal by determining the lower bounds of a ratio

6. A method as claimed in claim 1, characterised by deriving the Fourier transform of the power spectrum density of the received signal, noting the amplitudes of all the reflection peaks, calculating a DC component and determining if the calculated value corresponds to a value associated with LOS being present.

7. A position determining apparatus comprising receiving means for receiving a positioning signal from a remote transmitter, means for determining if a line-of-sight (LOS) signal is present and means using the LOS signal for determining the position of the remote transmitter.

8. A position determining apparatus as claimed in claim 7, characterised by means for deriving the Fourier transform of a power spectrum density of the received signal, means for determining if a peak is present in the power spectrum density at zero frequency, and means for implementing multipath mitigation to identify a line-of-sight (LOS)

9. An apparatus as claimed in claim 8, characterised by means responsive to a LOS signal being absent for inhibiting the multipath mitigation means.

10. An apparatus as claimed in claim 7, characterised in that the means for determining if a peak is present at zero frequency comprises means for deriving the Fourier transform of a power spectrum density of the received signal, means for determining the quotient of the magnitude of a peak at zero frequency divided by the maximum magnitude of all the other peaks and means for determining if the answer is less than unity, thereby indicating that LOS is not present.

11. An apparatus as claimed in claim 7, characterised in that the means for determining if a peak is present at zero frequency comprises means for deriving the Fourier transform of a power spectrum density of the received signal, means for determining the lower bounds of a ratio

12. An apparatus as claimed in claim 7, characterised by means for deriving the Fourier transform of the power spectrum density of the received signal, means for noting the amplitude of all the reflection peaks, excluding the beat frequency peaks, and means for calculating a DC component and for determining if the calculated value corresponds to a value associated with LOS being present.