GPS signal acquisition system and method

• US 7,949,035 B2
• Filed: 12/15/2006
• Issued: 05/24/2011
• Est. Priority Date: 06/16/2006
• Status: Active Grant

• Current Assignee: VIA Technologies Incorporated (VIA Technologies)
• Original Assignee: VIA Technologies Incorporated (VIA Technologies)
• Inventors: Su, Fei
• Primary Examiner(s): Liu; Shuwang
• Assistant Examiner(s): Singh; Hirdepal
• Application Number:
  US11/611,162
• Publication Number:
  US 20070291824A1
• Time in Patent Office: 1,621 Days
• Field of Search: 375135-136, 375145-147, 375/150, 375/290, 375/292, 375/295, 375/297, 375/306, 375/316, 375342-343, 375242-244, 375/148, 375/299, 375/137, 375/259, 375/345, 375/346, 375/348, 375/350
• US Class Current: 375/147
• CPC Class Codes: G01S 19/24 Acquisition or tracking or demodulation of signals transmitted by the system synchronisation aspects of direct sequence spread spectrum modulation H04B1/7073
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: H04B 1/7075 with code phase acquisition
• CPC Class Codes: H04B 1/7083 Cell search, e.g. using a three-step approach
• CPC Class Codes: H04B 2201/70715 with application-specific features

Abstract

A Global Position System signal acquiring system and method is provided in this invention. Pluralities of counters are set, each corresponding to a code bin and a frequency bin of the signal. Subsequently, the signal corresponding to the counters is repeatedly received in a unit of time and the counters are accordingly updated for a pre-determined iteration. At last, a maximum value among the counters is found to acquire the signal corresponding to the counter having the maximum value.

Claims

1. A method for locating a target cell among a plurality of cells corresponding to a GPS (Global Position System) signal, with the plurality of cells forming a two-dimensional array, wherein each row of the two-dimensional array corresponds to a code bin of the GPS signal and each column of the two-dimensional array corresponds to a frequency bin of the GPS signal, the method comprising:

(1) providing a plurality of counters, each corresponding to one of the plurality of cells;

(2) receiving the GPS signal in a unit of time in a detecting frequency bin;

(3) decoding the received GPS signal with each of the corresponding code bins with respect to first cells corresponding to the detecting frequency bin to generate a corresponding decoding result in a decoding vector;

(4) comparing each of the decoding results in the decoding vector with a threshold to update a corresponding counter with respect to one of the first cells in a two-dimensional counter vector;

(5) repeatedly performing the steps (2)-(4) for a predetermined iteration if any of the corresponding counters exceeds a limit value;

(6) determining whether the steps (2)-(4) have been performed for all of the plurality of cells;

(7) filtering the plurality of counters to generate filtered results;

(8) finding a most likely cell having a maximum value among the filtered results; and

(9) setting the most likely cell to be the target cell for acquisition of the GPS signal.

2. The method as claimed in claim 1, wherein the step (4) further comprises:

increasing one of the corresponding counters by one if the corresponding decoding result exceeds or equals to the threshold; and

decreasing the one of the corresponding counters by one if the corresponding decoding result is less than the threshold.

3. The method as claimed in claim 1, wherein the unit of time is about 1 ms.

4. The method as claimed in claim 1, wherein the predetermined iteration is adjustable based on parameters of an environment.

5. The method as claimed in claim 1, wherein the filtering further comprises utilizing a FIR (finite impulse response) filter.

6. The method as claimed in claim 1, wherein the threshold is adjustable based on parameters of an environment.

7. The method as claimed in claim 1, wherein the decoding comprises a FFT (fast Fourier transformation) operation.

8. A GPS receiver for searching a target cell among a plurality of cells corresponding to a GPS signal, the plurality of cells forming a two-dimensional array, wherein each row of the two-dimensional array corresponds to a code bin of the GPS signal and each column of the two-dimensional array corresponds to a frequency bin of the GPS signal, a plurality of counters corresponding to the cells, the GPS receiver comprising:

an antenna module for receiving an emitted signal of a GPS satellite;

a signal decoding and processing module for decoding a received signal in a unit of time in a detecting frequency bin with corresponding code bins with respect to first cells corresponding to the detecting frequency bin to generate a corresponding decoding result of each of the corresponding code bins in a decoding vector;

a detector for comparing each of the decoding results in the decoding vector with a threshold to update a corresponding counter with respect to each of the first cells in a two-dimensional counter vector; and

a filter for filtering the plurality of counters to find a most likely cell having a maximum value among the plurality of counters and set the most likely cell as the target cell;

wherein, if one of the corresponding counters exceeds a limit value, the signal decoding and processing module and the detector repeatedly decode, compare and update the corresponding counter for a predetermined iteration.

9. The GPS receiver as claimed in claim 8, wherein the detector comprises at least one comparator for comparing each of the decoding results with the threshold.

10. The GPS receiver as claimed in claim 8, wherein the detector increases a corresponding counter by one when the corresponding decoding result exceeds or equals to the threshold, and decreases a corresponding counter by one when the corresponding decoding result is less than the threshold.

11. The GPS receiver as claimed in claim 8, wherein the filter is a FIR filter.

12. The GPS receiver as claimed in claim 8, wherein the signal decoding and processing module comprises a module for performing FFT operation.