Signal acquisition using data bit information

• US 6,933,886 B1
• Filed: 12/11/2002
• Issued: 08/23/2005
• Est. Priority Date: 06/22/2001
• Status: Expired due to Term

• Current Assignee: CSR Technology Holdings Inc. (Qualcomm, Inc.)
• Original Assignee: SIRF Technology Incorporated (Qualcomm, Inc.)
• Inventors: Chou, Andrew, Roy, Benjamin Van, Mann, Wallace, Sahai, Anant
• Primary Examiner(s): PHAN, DAO LINDA
• Application Number:
  US10/316,992
• Time in Patent Office: 986 Days
• Field of Search: 342/357.05, 342/357.06, 342/357.12, 342/357.15, 701/213, 701/215
• US Class Current: 342/357.63
• CPC Class Codes: G01S 19/06 employing an initial estimate of the location of the receiver as aiding data or in generating aiding data
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver
• 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 19/30 code related G01S19/246 takes precedence

Abstract

Techniques are provided for aiding in acquiring a signal using the data bit information that is associated with each signal source. One aspect of the invention is to use the data bit information that is associated with each signal source when calculating the In Phase and Quadrature correlation integrals by using the sampled data associated with the received signal. By using the data bit information that is associated with each signal source, coherent correlation may be performed by breaking the signal into data blocks and performing calculations on a block-by-block basis. Coherent correlation is the calculation of In Phase and Quadrature correlation integrals for sampled data that is associated with the received signal.

Claims

1. A method for searching a received signal for a modulated signal comprising:

sampling said received signal to obtain sampled data of said received signal;

obtaining data bit information that indicates which portions of said modulated signal have a sign change;

processing said sampled data of said received signal, to yield processed data;

dividing said processed data into a plurality of data blocks; and

for one or more of said data blocks, computing I and Q correlation integrals between said sampled data and said modulated signal based on said data bit information.

2. The method of claim 1, wherein said processing said sampled data comprises mixing said sampled data.

3. The method of claim 1, further comprising the step of summing said I and Q correlation integrals over said plurality of data blocks, to yield summed I and Q correlation integrals.

4. The method of claim 3, further comprising the steps of calculating correlation magnitudes from said summed I and Q correlation integrals and comparing said correlation magnitudes to a threshold.

5. The method of claim 3, further comprising the steps of calculating correlation magnitudes from said summed I and Q correlation integrals and determining that said modulated signal is acquired if a highest peak of said correlation magnitudes is higher than a threshold.

6. The method of claim 1, wherein said computing I and Q correlation integrals comprises making a code-phase adjustment.

7. The method of claim 1, wherein said computing I and Q correlation integrals comprises calculating a fast fourier transform of one or more of said data blocks.

8. The method of claim 7, further comprising making integer code phase adjustments and performing a block summing before said fast fourier transform.

9. The method of claim 8, wherein said I and Q correlation integrals are calculated for a range of hypothesized delay values based on an approximate receipt time of said received signal and an approximate distance between a receiver receiving said received signal and a source transmitting said modulated signal.

10. The method of claim 9 wherein said processing said sampled data comprises mixing said sampled data.

11. The method of claim 7, further comprising performing a block summing before said fast fourier transform.

12. The method of claim 11, wherein said I and Q correlation integrals are calculated for a range of hypothesized delay values based on an approximate receipt time of said received signal and an approximate distance between a receiver receiving said received signal and a source transmitting said modulated signal.

13. The method of claim 12, wherein said processing said sampled data comprises mixing said sampled data.

14. The method of claim 1, wherein said I and Q correlation integrals are calculated for a range of hypothesized delay values based on an approximate receipt time of said received signal and an approximate distance between a receiver receiving said received signal and a source transmitting said modulated signal.

15. The method of claim 14, wherein said processing said sampled data comprises mixing said sampled data.

16. The method of claim 5, wherein said I and Q correlation integrals are calculated for a range of hypothesized delay values based on an approximate receipt time of said received signal and an approximate distance between a receiver receiving said received signal and a source transmitting said modulated signal.

17. The method of claim 16, wherein said processing said sampled data comprises mixing said sampled data.

18. The method of claim 5, wherein said computing I and Q correlation integrals comprises performing a block summing and calculating a fast fourier transform of one or more of said data blocks.

19. The method of claim 18, wherein said I and Q correlation integrals are calculated for a range of hypothesized delay values based on an approximate receipt time of said received signal and an approximate distance between a receiver receiving said received signal and a source transmitting said modulated signal.

20. The method of claim 19, wherein said processing said sampled data comprises mixing said sampled data.

21. The method of claim 5, wherein said computing I and Q correlation integrals comprises making integer code-phase adjustments, performing a block summing and calculating a fast fourier transform of one or more of said data blocks.

22. The method of claim 21, wherein said I and Q correlation integrals are calculated for a range of hypothesized delay values based on an approximate receipt time of said received signal and an approximate distance between a receiver receiving said received signal and a source transmitting said modulated signal.

23. The method of claim 22, wherein said processing said sampled data comprises mixing said sampled data.

24. A medium storing instructions to be executed by a processor for searching a received signal for a modulated signal comprising:

instructions for sampling said received signal, to obtain sampled data of said received signal;

instructions for obtaining data bit information that indicates which portions of said modulated signal have a sign change;

instructions for processing said sampled data of said received signal, to yield processed data;

instructions for dividing said processed data into a plurality of data blocks; and

instructions for computing I and Q correlation integrals between said sampled data and said modulated signal based on said data bit information, for one or more of said data blocks.

25. A device for searching a received signal for a modulated signal comprising:

means for sampling said received signal, to obtain sampled data of said received signal;

means for obtaining data bit information that indicates which portions of said modulated signal have a sign change;

means for processing said sampled data of said received signal, to generate processed data;

means for dividing said processed data into a plurality of data blocks; and

means for computing I and Q correlation integrals between said sampled data and said modulated signal based on said data bit information, for one or more of said data blocks.