GPS SIGNAL ACQUISITION SYSTEM AND METHOD

• US 20070291824A1
• Filed: 12/15/2006
• Published: 12/20/2007
• 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
• Granted Patent: US 7,949,035 B2
• Time in Patent Office: Days
• 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 signal in a unit of time in a detecting frequency bin;

(3) decoding the received signal with one corresponding code bin with respect to a first cell of the cells to generate at least one decoding result;

(4) comparing the decoding result with a threshold to update a corresponding counter with respect to the first cell;

(5) repeatedly performing the steps (2)-(4) for a predetermined iteration if the corresponding counter 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 the corresponding counter by one if the decoding result exceeds or equals to the threshold; and

decreasing the corresponding counter by one if the 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 the parameters of the 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 the parameters of the 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 the 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 a corresponding code bin with respect to a first cell of the plurality of cells to generate a decoding result;

a detector for comparing the decoding result with a threshold to update a corresponding counter with respect to the first cell; and

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

wherein, if the corresponding counter 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 the decoding result with the threshold.

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

13. A method for acquisition of a GPS signal, comprising:

setting a plurality of counters, each corresponding to a code bin and a frequency bin of the GPS signal;

repeatedly receiving the signal corresponding to searched counters in a unit of time and updating the searched counters for a pre-determined iteration; and

finding a maximum value among the searched counters to acquire the signal using the code bin and the frequency bin corresponding to the counter having the maximum value.

14. The method as claimed in claim 13, wherein repeatedly receiving and updating further comprises:

decoding received signal with corresponding code bins with respect to the searched counters to generate decoding results; and

comparing the decoding results with a threshold to update the searched counters;

15. The method as claimed in claim 14, wherein receiving and updating is repeated when one of the searched counters exceeds a limit value.

16. The method as claimed in claim 14, further comprising:

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

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

17. The method as claimed in claim 13, wherein the predetermined iteration is adjustable based on the parameters of the environment.

18. The method as claimed in claim 13, further comprising:

filtering the searched counters to locate the maximum value among the searched counters.

19. The method as claimed in claim 18, wherein filtering is performed by a FIR filter.

20. The method as claimed in claim 14, wherein decoding comprises a FFT operation.