Modernized global navigation satellite system (GNSS) receivers and commercially viable consumer grade GNSS receivers
GNSS receivers and systems within such receivers use improvements to reduce memory usage while providing sufficient processing resources to receive and acquire and track E5 band GNSS signals directly (without attempting in one embodiment to receive L1 GNSS signals). Other aspects are also described.
1. A method for processing GNSS signals, the method comprising:
receiving, by a GNSS receiver, GNSS signals;
digitizing the received GNSS signals and providing an output, from an analog to digital converter (ADC) in the GNSS receiver, of GNSS sample data which includes one or more of (1) GNSS sideband A sample data from the received GNSS signals or (2) GNSS sideband B sample data from the received GNSS signals;
computing a first set of discrete Fourier transforms (DFTs) of the GNSS sample data to provide a first set of results;
computing a second set of DFTs of a first GNSS primary PRN code data which is adjusted for code Doppler and carrier Doppler prior to the second set of DFTs, the second set of DFTs providing a second set of results;
computing a first set of correlations of the received GNSS signals and the first GNSS primary PRN code based on the first set of results and the second set of results to provide a third set of results;
integrating the third set of results with at least one prior sum, wherein the integrating includes storing at least one new sum for the correlation of the first GNSS primary PRN code with the received GNSS signals.
2. The method as in claim 1 , wherein the GNSS receiver receives and processes only GNSS signals in an L5 radio frequency (RF) band and does not use GNSS signals in an L1 RF band.
3. The method as in claim 1 , wherein the second set of results provide a code spectrum for use in correlations of the first GNSS primary code data with the GNSS sample data.
4. The method as in claim 1 , wherein the first GNSS primary PRN code data is either stored in the GNSS receiver or generated in the GNSS receiver during an acquisition phase in the GNSS receiver.
5. The method as in claim 3 , wherein the GNSS receiver also receives and processes GNSS signals in an L1 RF band.
6. The method as in claim 3 , wherein the GNSS sample data includes the GNSS sideband A sample data from the received GNSS signals, and the GNSS sideband A sample data includes one or more components.
7. The method as in claim 6 , wherein the one or more components of the GNSS sideband A sample data include an E5AI component which includes a second GNSS primary PRN code data and an E5AQ component which includes the first GNSS primary PRN code data, and wherein the method further comprises:
computing a third set of DFTs of the second GNSS primary PRN code data which is adjusted for code Doppler and carrier Doppler prior to the third set of DFTs, the third set of DFTs providing a fourth set of results;
computing a second set of correlations of the received GNSS signals and the second GNSS primary PRN code based on the first set of results and the fourth set of results to provide a fifth set of results;
integrating the fifth set of results with at least one prior sum, wherein the integrating of the fifth set of results includes storing at least one new sum for the correlation of the second GNSS primary PRN code data with the received GNSS signals.
8. The method as in claim 7 , wherein the GNSS sample data includes the GNSS sideband B sample data from the received GNSS signals, and the GNSS sideband B sample data includes one or more components which include an E5BI component which includes a third GNSS primary PRN code data and an E5BQ component which includes a fourth GNSS primary PRN code data, and wherein the method further comprises:
computing a fourth set of DFTs of the GNSS sideband B sample data to provide a sixth set of results;
computing a fifth set of DFTs of the third GNSS primary PRN code data which is adjusted for code Doppler and carrier Doppler prior to the fifth set of DFTs, the fifth set of DFTs providing a seventh set of results;
computing a third set of correlations of the received GNSS signals and the third GNSS primary PRN code based on the sixth set of results and the seventh set of results to provide an eighth set of results;
integrating the eighth set of results with at least one prior sum, wherein the integrating of the eighth set of results includes storing at least one new sum for the correlation of the third GNSS primary PRN code data with the received GNSS signals;
computing a sixth set of DFTs of the fourth GNSS primary PRN code data which is adjusted for code Doppler and carrier Doppler prior to the sixth set of DFTs, the sixth set of DFTs providing a ninth set of results;
computing a fourth set of correlations of the received GNSS signals and the fourth GNSS primary PRN code based on the sixth set of results and the ninth set of results to provide a tenth set of results;
integrating the tenth set of results with at least one prior sum, wherein the integrating of the tenth set of results includes storing at least one new sum for the correlation of the fourth GNSS primary PRN code data with the received GNSS signals.
9. The method as in claim 3 , wherein the GNSS sample data includes the GNSS sideband B sample data from the received GNSS signals, and the GNSS sideband B sample data includes an E5BI component which includes a second GNSS primary PRN code data and an E5BQ component which includes the first GNSS primary PRN code data, and wherein the method further comprises:
computing a third set of DFTs of the second GNSS primary PRN code data which is adjusted for code Doppler and carrier Doppler prior to the third set of DFTs, the third set of DFTs providing a fourth set of results;
computing a second set of correlations of the received GNSS signals and the second GNSS primary PRN code based on the first set of results and the fourth set of results to provide a fifth set of results;
integrating the fifth set of results with at least one prior sum, wherein the integrating of the fifth set of results includes storing at least one new sum for the correlation of the second GNSS primary PRN code data with the received GNSS signals.
10. The method as in claim 7 , wherein the GNSS receiver includes time domain correlators, and the time domain correlators are used in a tracking mode after GNSS signals have been acquired by processing logic that computes DFTs.
11. The method as in claim 10 , wherein the GNSS receiver includes a GNSS processing system that includes an acquisition engine and a tracking engine, and the acquisition engine includes the processing logic to receive an array of GNSS sample data, arranged, according to time of receipt, in either row order or column order and stored in one or more circular buffers.
12. The method as in claim 11 , wherein a code spectrum data for each of the first GNSS primary PRN code data and the second GNSS primary PRN code data are generated repeatedly during a time period while acquiring GNSS signal components that include the first GNSS primary PRN code data and the second GNSS primary PRN code data and wherein the code spectrum data is generated in place in the acquisition engine.
13. The method as in claim 12 , wherein the GNSS sample data is processed to separate the GNSS sideband A sample data from the GNSS sideband B sample data by: (1) for the GNSS sideband A, shifting samples centered at a first frequency up by a first offset frequency and performing a low pass filter to capture a first bandwidth of data and decimating the output of the low pass filter to a lower sample rate; and (2) for the GNSS sideband B, shifting samples centered at the first frequency down by the first offset frequency and performing a low pass filter to capture a second bandwidth of data and decimating the output of the low pass filter to a lower sample rate.
14. The method as in claim 7 , wherein the computing operations require no separate operations to transpose or rearrange the sample data or the generated code spectrum data.
15. The method as in claim 7 , wherein a code generator generates at least one of (1) the GNSS sideband A primary PRN code data every millisecond while GNSS signals are being acquired and tracked and the GNSS sideband A primary PRN code date is not stored after Fourier transformations are completed, and (2) the GNSS sideband B primary PRN code data every millisecond while the GNSS signals are being acquired and tracked and the GNSS sideband B primary PRN code data is not stored after Fourier transformations are completed.
16. The method as in claim 15 , wherein the integrating is non-coherent during at least a portion of an acquisition phase while the GNSS signals are received.
17. A GNSS receiver comprising:
a radiofrequency analog to digital converter (ADC) to generate a digital representation of received GNSS signals;
a sample memory to store the digital representation of the received GNSS signals as digitized GNSS sample data, the sample memory configured to store the digitized GNSS sample data;
a GNSS processing system coupled to the sample memory, the GNSS processing system configured to process the GNSS sample data which includes one or more of (1) GNSS sideband A sample data from the received GNSS signals or (2) GNSS sideband B sample data from the received GNSS signals; and the GNSS processing system is configured to:
compute a first set of discrete Fourier transforms (DFTs) of the GNSS sample data to provide a first set of results;
compute a second set of DFTs of a first GNSS primary PRN code data which is adjusted for code Doppler and carrier Doppler prior to the second set of DFTs, the second set of DFTs providing a second set of results;
compute a first set of correlations of the received GNSS signals and the first GNSS primary PRN code based on the first set of results and the second set of results to provide a third set of results;
integrate the third set of results with at least one prior sum, wherein the integrating of the third set of results includes storing at least one new sum for the correlation of the first GNSS primary PRN code data with the received GNSS signals.
18. The GNSS receiver as in claim 17 , wherein the GNSS receiver receives and processes only GNSS signals in an L5 radio frequency (RF) band and does not use GNSS signals in an L1 RF band, and wherein the second set of results provide a code spectrum for use in correlations of the first GNSS primary code data with the GNSS sample data, and wherein the first GNSS primary PRN code data is either stored in the GNSS receiver or generated in the GNSS receiver during an acquisition phase in the GNSS receiver.
19. The GNSS receiver as in claim 17 , wherein the GNSS receiver also receives and processes GNSS signals in an L1 RF band.
20. The GNSS receiver as in claim 17 , wherein the GNSS sample data includes the GNSS sideband A sample data from the received GNSS signals, and the GNSS sideband A sample data includes an E5AI component which includes a second GNSS primary PRN code data and an E5AQ component which includes the first GNSS primary PRN code data, and wherein the GNSS processing system is configured to:
compute a third set of DFTs of the second GNSS primary PRN code data which is adjusted for code Doppler and carrier Doppler prior to the third set of DFTs, the third set of DFTs providing a fourth set of results;
compute a second set of correlations of the received GNSS signals and the second GNSS primary PRN code based on the first set of results and the fourth set of results to provide a fifth set of results;
integrate the fifth set of results with at least one prior sum, wherein the integrating of the fifth set of results includes storing at least one new sum for the correlation of the second GNSS primary PRN code data with the received GNSS signals.
21. The GNSS receiver as in claim 17 , wherein the GNSS sample data includes the GNSS sideband B sample data from the received GNSS signals, and the GNSS sideband B sample data includes an E5BI component which includes a second GNSS primary PRN code data and an E5BQ component which includes the first GNSS primary PRN code data, and wherein the GNSS processing system is configured to:
compute a third set of DFTs of the second GNSS primary PRN code data which is adjusted for code Doppler and carrier Doppler prior to the third set of DFTs, the third set of DFTs providing a fourth set of results;
compute a second set of correlations of the received GNSS signals and the second GNSS primary PRN code based on the first set of results and the fourth set of results to provide a fifth set of results;
integrate the fifth set of results with at least one prior sum, wherein the integrating of the fifth set of results includes storing at least one new sum for the correlation of the second GNSS primary PRN code data with the received GNSS signals.
22. The GNSS receiver as in claim 17 , wherein the GNSS receiver includes time domain correlators, and the time domain correlators are used in a tracking mode after GNSS signals have been acquired by processing logic that computes DFTs.
23. The GNSS receiver as in claim 17 , wherein a code spectrum data for each of the first GNSS primary PRN code data and the second GNSS primary PRN code data are generated repeatedly during a time period while acquiring GNSS signal components that include the first GNSS primary PRN code data and the second GNSS primary PRN code data.
24. The GNSS receiver as in claim 23 , wherein a code generator in the GNSS receiver generates at least one of (1) the GNSS sideband A primary PRN code data every millisecond while GNSS signals are being acquired and the GNSS sideband A primary PRN code date is not stored after Fourier transformations are completed, and (2) the GNSS sideband B primary PRN code data every millisecond while the GNSS signals are being acquired and the GNSS sideband B primary PRN code data is not stored after Fourier transformations are completed.
25. The GNSS receiver as in claim 23 , wherein the code spectrum data is generated in place in an acquisition engine.
26. A method for processing GNSS signals, the method comprising:
receiving, by a GNSS receiver, GNSS signals;
digitizing the received GNSS signals and providing an output, from an analog to digital converter (ADC) in the GNSS receiver, of GNSS sample data which includes one or more of (1) GNSS sideband A sample data from the received GNSS signals or (2) GNSS sideband B sample data from the received GNSS signals;
computing a first set of discrete Fourier transforms (DFTs) of the GNSS sample data to provide a first set of results;
computing a second set of DFTs of a first GNSS primary PRN code, the second set of DFTs providing a second set of results;
computing a first set of correlations of the received GNSS signals and the first GNSS primary PRN code based on the first set of results and the second set of results to provide a third set of results;
integrating the third set of results with at least one prior sum, wherein the integrating of the third set of results includes storing at least one new sum for the correlation of the first GNSS primary PRN code with the received GNSS signals in a single hypothesis memory;
computing a third set of DFTs of a second GNSS primary PRN code data, the third set of DFTs providing a fourth set of results;
computing a second set of correlations of the received GNSS signals and the second GNSS primary PRN code based on the first set of results and the fourth set of results to provide a fifth set of results;
integrating the fifth set of results with at least one prior sum, wherein the integrating of the fifth set of results includes storing at least one new sum for the correlation of the second GNSS primary PRN code data with the received GNSS signals in the single hypothesis memory such that the single hypothesis memory contains the combined sums from the integrating of the fifth set of results and the third set of results.
27. The method as in claim 26 , wherein the first GNSS primary PRN code and the second GNSS primary PRN code are contained in the GNSS sideband A sample data from the received GNSS signals.
28. The method as in claim 26 , wherein the first GNSS primary PRN code and the second GNSS primary PRN code are contained in the GNSS sideband B sample data from the received GNSS signals.
29. The method as in claim 26 , wherein the integrating of the third set of results and the fifth set of results comprises non-coherent integration.
30. The method as in claim 26 , wherein the GNSS receiver receives and processes only GNSS signals in an L5 radio frequency (RF) band and does not use GNSS signals in an L1 RF band.
31. The method as in claim 26 , wherein a code spectrum data for each of the first GNSS primary PRN code and the second GNSS primary PRN code are generated repeatedly during a time period while acquiring GNSS signal components that include the first GNSS primary PRN code data and the second GNSS primary PRN code data, and wherein the time period is more than two milliseconds.