Method and system for data detection in a global positioning system satellite receiver

• US 6,714,158 B1
• Filed: 04/18/2000
• Issued: 03/30/2004
• Est. Priority Date: 04/18/2000
• Status: Expired due to Term

• Current Assignee: CSR Technology Incorporated (Qualcomm, Inc.)
• Original Assignee: SIRF Technology Incorporated (Qualcomm, Inc.)
• Inventors: Gronemeyer, Steven A., Underbrink, Paul A.
• Primary Examiner(s): Tarcza, Thomas H.
• Assistant Examiner(s): MULL, FRED H
• Application Number:
  US09/552,759
• Time in Patent Office: 1,442 Days
• Field of Search: 342/357.12, 342/357.15, 342/357.06, 375/152, 375/153, 375/143, 375/343, 708/314
• US Class Current: 342/357.63
• 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 19/243 Demodulation of navigation message
• CPC Class Codes: G01S 19/30 code related G01S19/246 takes precedence
• CPC Class Codes: G01S 19/37 Hardware or software details of the signal processing chain
• CPC Class Codes: H04B 1/707 using direct sequence modulation

Abstract

A data detection circuit within a global positioning system (GPS) satellite receiver operates to detect and decode data sent in a spread spectrum signal. The data detection circuit receives input from a radio receiver, the information containing data from a plurality of satellites. The data is supplied to a circular memory device, which determines which data corresponds to which satellite. The memory device sends the received signal to a matched filter, which decodes the signal received from each satellite. This signal is analyzed to determine whether a phase inversion due to data modulation on the received signal is present. The phase inversion can occur at boundaries, known as data epochs, in the received signal, and corresponds to data in the received signal. This data contains information relating to the position of each satellite and is collected by the data detection circuit for use by the GPS receiver.

Claims

1. A method for processing global positioning system (GPS) signals, comprising:

receiving serial GPS data on a first data bus, wherein the GPS data includes data bits from at least one satellite;

switching the GPS data from the first data bus to a plurality of memory elements via a first plurality of corresponding switches, wherein the GPS data from one or more of the at least one satellites is stored in a same word in the plurality of memory elements; and

extracting the GPS data for processing from words stored in the memory elements such that GPS data from a particular one of the at least one satellites is assembled for processing.

2. The method of claim 1, further comprising switching the GPS data from the plurality of memory elements to a second data bus via a second plurality of corresponding switches.

3. The method of claim 2, wherein switching comprises generating a memory address for controlling one of the first and second pluralities of corresponding switches, wherein a memory address corresponds to a word.

4. The method of claim 3, further comprising:

storing the GPS data in the plurality of memory elements in a continuous, circular addressing mode; and

reading the GPS data out of the plurality of memory elements in a continuous, circular addressing mode.

5. The method of claim 3, wherein extracting data further comprises:

transmitting the GPS data from the second data bus in serial; and

extracting GPS data for one or more of the at least one satellites from a word, such that GPS data from one satellite is assembled for processing.

6. The method of claim 5, further comprising:

providing Doppler information specific to the one satellite; and

mixing the assembled GPS data with the Doppler information to produce a shifted spectrum of the one satellite.

7. The method of claim 6, further comprising correlating the shifted spectrum with a reference signal that is a replica of GPS signal for the one satellite.

8. The method of claim 7, further comprising repeating the providing, mixing and correlating for a plurality of shifted spectra of the one satellite over a code period.

9. The method of claim 2, further comprising coordinating switching from the first bus and switching from the memory elements.

10. The method of claim 1, wherein the GPS data is stored in the plurality of memory elements as one-ms code periods.

11. The method of claim 1, wherein the GPS data is stored in the plurality of memory elements as twenty-ms data periods.

12. An apparatus for processing global positioning system (GPS) signals, comprising:

a memory device configured to receive serial GPS data on a first data bus, wherein the GPS data includes data bits from at least one satellite;

at least one first switching device coupled to memory device and to the first data bus and configured to switch the GPS data from the first data bus to a plurality of memory elements in the memory device, wherein the GPS data from one or more of the at least one satellites is stored in a same word in the plurality of memory elements; and

a data extraction element coupled to the memory device and configured to extract the GPS data for processing from words stored in the memory elements such that GPS data from a particular one of the at least one satellites is assembled for processing.

13. The apparatus of claim 12, further comprising at least one second switching device coupled the memory device and to a second data bus and configured to switch the GPS data from the plurality of memory elements to the second data bus.

14. The apparatus of claim 13, further comprising at least one address generator coupled to the first data bus and the second data bus and configured to generate a memory address for controlling one of the at least one first and at least one second switching devices, wherein a memory address corresponds to a word.

15. The apparatus of claim 14, wherein the memory device is configured to store the GPS data in the memory device in a continuous, circular addressing mode, and further configured to allow the GPS data to be read out of the memory device in a continuous, circular addressing mode.

16. The apparatus of claim 14, wherein the data extraction element is configured to receive the GPS data from the second data bus in serial and extract GPS data for one or more of the at least one satellites from a word, such that GPS data from one satellite is assembled for processing.

17. The apparatus of claim 16, further comprising:

a Doppler generator configured to generate Doppler information specific to the one satellite, wherein; and

a mixer coupled to the Doppler generator to receive the Doppler information and the assembled GPS data, and to produce a shifted spectrum of the one satellite.

18. The apparatus of claim 17, further comprising a matched filter coupled to the data extraction element and configured to correlate the shifted spectrum with a reference signal that is a replica of GPS signal for the one satellite.

19. The apparatus of claim 13, further comprising at least one state machine coupled to the at least one address generator for coordinating switching from the first bus and switching from the memory device.

20. The apparatus of claim 12, wherein the GPS data is stored in the plurality of memory elements as one-ms code periods.

21. The apparatus of claim 12, wherein the GPS data is stored in the plurality of memory elements as twenty-ms data periods.

22. An apparatus for global positioning system (GPS) signal processing, comprising:

a memory that receives serial GPS data from multiple GPS satellites and stores the GPS data in data words, wherein a data word includes GPS data from more than one satellite; and

an address generator coupled to the memory device, wherein the address generator is configured to receive and instruction regarding a particular GPS satellite signal to be processed, and generate an address corresponding to a data epoch for a data period of the particular GS satellite.