SYSTEMS AND METHODS FOR DETECTING SATELLITE SIGNALS

• US 20130229305A1
• Filed: 03/05/2012
• Published: 09/05/2013
• Est. Priority Date: 03/05/2012
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: Nayyar, Jasbir Singh, Tangudu, Jawaharlal, Ganesan, Aravind
• Granted Patent: US 9,612,339 B2
• Time in Patent Office: Days
• US Class Current: 342/357.63
• CPC Class Codes: G01S 19/29 carrier including Doppler, related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence

Abstract

A GNSS receiver configured to detect a presence of at least one GNSS satellite signal in a received signal is provided. The GNSS receiver includes a buffer loaded with sample sets corresponding to the received signal and a Doppler derotation block configured to perform a Doppler derotation corresponding to at least one Doppler frequency on a sample set received from the buffer. The GNSS receiver further includes an accumulator block configured to perform a coherent accumulation of a plurality of sample sets upon or subsequent to the Doppler derotation corresponding to a Doppler frequency, and, a first memory configured to store the results of the coherent accumulation. A register array is configured to be loaded with the results stored in the first memory and a correlator engine is configured to generate correlation results by correlating the results in the register array with a plurality of code phases of GNSS satellites.

Claims

1. A global navigation satellite system (GNSS) receiver comprising:

a buffer configured to be loaded with sample sets corresponding to a received signal;

a Doppler derotation block configured to receive a sample set from among the sample sets loaded in the buffer and perform a Doppler derotation corresponding to at least one Doppler frequency on the sample set;

an accumulator block configured to perform coherent accumulation of a plurality of sample sets upon or subsequent to a Doppler derotation corresponding to a Doppler frequency from among the at least one Doppler frequency, wherein the coherent accumulation is performed based on a pre-determined coherent accumulation period;

a first memory configured to store results of the coherent accumulation;

a register array configured to be loaded with the results stored in the first memory; and

a correlator engine configured to facilitate a search of GNSS satellite signals in the received signal by correlating the results loaded in the register array with a plurality of code phases of GNSS satellites.

2. The GNSS receiver of claim 1, further comprises:

a control sequencing block configured to schedule a sequence of searches for the GNSS satellite signals by scheduling an order of Doppler frequencies configured to perform Doppler derotation and an order of a plurality of code phases of the GNSS satellites for performing correlation.

3. The GNSS receiver of claim 2, wherein scheduling the sequence of searches comprises:

allocating a start timing reference for each search for a GNSS satellite signal.

4. The GNSS receiver of claim 3, wherein the start timing reference is allocated based on a load status associated with a number of searches for GNSS satellite signals in the received signal.

5. The GNSS receiver of claim 4, wherein the start timing reference is allocated based on a least load status associated with the number of searches for GNSS satellite signals in the received signal.

6. The GNSS receiver of claim 3, further comprising:

performing each search for GNSS satellite signals in the received signal based on the allocated start timing reference and the pre-determined coherent accumulation period.

7. The GNSS receiver of claim 1, further comprising:

a processor block configured to perform non-coherent accumulation of correlation results obtained by correlating the results loaded in the register array with the plurality of code phases of the GNSS satellites.

8. The GNSS receiver of claim 7, further comprising:

a second memory configured to store the non-coherent accumulation of the correlation results.

9. The GNSS receiver of claim 8, wherein the processor block is further configured to detect a presence of at least one GNSS satellite signal based on the non-coherent accumulation of the correlation results.

10. The GNSS receiver of claim 1, wherein the sample sets are cyclically loaded into the buffer.

11. The GNSS receiver of claim 1, wherein the pre-determined coherent accumulation period corresponds to one of a 1 millisecond (ms) time period, 5 ms time period, 9 ms time period, 11 ms time period and 19 ms time period.

12. A global navigation satellite system (GNSS) receiver comprising:

a buffer configured to be loaded with sample sets corresponding to a received signal;

a Doppler derotation block configured to receive a sample set from among the sample sets loaded in the buffer and perform a Doppler derotation corresponding to at least one Doppler frequency on the sample set;

a register array configured to be loaded with the sample set upon Doppler derotation corresponding to a Doppler frequency from among the at least one Doppler frequency;

a correlator engine configured to facilitate a search of GNSS satellite signals in the received signal by generating correlation results for the sample set by correlating the sample set loaded in the register array with a plurality of code phases of a GNSS satellite;

an accumulator block configured to perform a coherent accumulation of correlation results corresponding to a plurality of sample sets and the plurality of code phases of the GNSS satellite, wherein the coherent accumulation is performed based on a pre-determined coherent accumulation period; and

a first memory configured to store results of the coherent accumulation.

13. The GNSS receiver of claim 12, further comprising:

a processor block configured to perform non-coherent accumulation of the correlation results corresponding to the plurality of the sample sets.

14. The GNSS receiver of claim 13, further comprising:

a second memory configured to store the non-coherent accumulation of the correlation results.

15. The GNSS receiver of claim 14, wherein the processor block is further configured to detect a presence of at least one GNSS satellite signal based on at least one of the coherent accumulation and the non-coherent accumulation of the correlation results.

16. The GNSS receiver of claim 12, wherein the pre-determined coherent accumulation period corresponds to one of a 1 millisecond (ms) time period, 5 ms time period, 9 ms time period, 11 ms time period and 19 ms time period.

17. A method comprising:

performing a Doppler derotation corresponding to a Doppler frequency on a plurality of sample sets corresponding to a received signal;

performing a coherent accumulation of the plurality of sample sets upon or subsequent to the Doppler derotation corresponding to the Doppler frequency, wherein the coherent accumulation is performed based on a pre-determined coherent accumulation period; and

facilitating a search of GNSS satellite signals in the received signal by correlating the results of the coherent accumulation of a plurality of sample sets with plurality of code phases of GNSS satellites.

18. The method of claim 17, further comprising:

allocating a start timing reference for each search for a GNSS satellite signal based on a load status associated with a number of searches for GNSS satellite signals in the received signal.

19. The method of claim 18, further comprising:

performing each search for GNSS satellite signals in the received signal based on the allocated start timing reference and the pre-determined coherent accumulation period.

20. The method of claim 19, further comprising:

performing non-coherent accumulation of correlation results obtained by correlating the results of coherent accumulation of the plurality of sample sets with the plurality of code phases of the GNSS satellites; and

detecting a presence of at least one GNSS satellite signal based on the non-coherent accumulation of the correlation results.