US 6,327,473 B1 · Method and apparatus for increasing the sensitivity of a global positioning satellite receiver

Abstract

Method and apparatus providing enhanced sensitivity for GPS receivers by allowing coherent integration of a correlation over several code periods of a GPS signal in one embodiment, and by performing a time to frequency domain conversion to the output from a correlation processor in a second embodiment. In the case in which coherent integration is performed over several code periods, advantage is taken of the fact that CDMA cellular telephone base stations transmit information that allows the receiver to determine GPS time before beginning a GPS signal acquisition process. The integration can be expanded to include code periods from more than one bit period, if the GPS receiver takes advantage of the fact that known bit patterns are transmitted at particular times within the transmission from a GPS satellite. If no base station is within range, then the output from a correlator that integrates a correlation over one code period is used to generate values that are input to in a discrete time domain to frequency domain transform. The output from the transform will indicate the presence of a signal from a particular satellite and the offset between locally generated signal and the received GPS signal.

Claims18

Dependent claims

A method for improving the sensitivity of a Global Positioning System (GPS) receiver, the method including the steps of:

a) receiving a GPS signal from a GPS satellite;
b) determining whether the receiver has a source for synchronization to GPS time other than the GPS satellite itself;
and
c) if there is a source for synchronization to GPS time other than the GPS satellite itself, then:
1) determining, from the synchronization source, the boundaries of a plurality of code periods in the received GPS signl;
2) determining the amount of power in the received GPS signal by applying a particular code associated with a particular satellite to the received GPS signal during each of the plurality of code periods;
3) summing the power received during each code period to determine a total integrated power over the sum of the plurality of code periods;
and
4) processing the received GPS signal using information about the particular satellite if the total integrated power is greater than a threshold value.

6 more elements

Apparatus for improving the sensitivity of a Global Positioning System (GPS) receiver, the apparatus including:

a) means for receiving a GPS signal from a GPS satellite;
b) means for determining whether the receiver has a source for synchronization to GPS time other than the GPS satellite itself;
c) means, responsive to a determination that there is a source for synchronization to GPS time other than the GPS satellite itself, for:
1) determining, from the synchronization source, the boundaries of a plurality of code periods in the received GPS signal;
2) determining the amount of power in the received GPS signal by applying a particular code associated with a particular satellite to the received GPS signal during each of the plurality of code periods;
3) summing the power received during each code period to determine a total integrated power over the sum of the plurality of code periods;
and
4) processing the received GPS signal using information about the particular satellite if the total integrated power is greater than a threshold value.

5 more elements

Dependencies are inferred from the claim text.

Method and apparatus for increasing the sensitivity of a global positioning satellite receiver

Life of this patent

Method and apparatus for increasing the sensitivity of a global positioning satellite receiver

Life of this patent

Abstract

Claims18