Using multiple detection algorithms in positioning signal processing
View Patent ↗A systematic method for acquiring positioning signals, such as global positioning system (GPS) signals, uses different signal detection algorithms at different stages of signal detection. For example, a method for detecting multiple positioning signals may include first detecting a first positioning signal using a robust but less sensitive signal detection method, such as non-coherent integration. Based on the signal parameter values that allow detection of the first positional signal, detecting a second positioning signal using a more sensitive method, such as coherent integration. In this manner, by capturing the strongest signal first using a robust method, signal detection parameter values common to positioning signals can be narrowed to allow subsequent signal acquisitions using a more sensitive—but computationally more intensive—method.
1. A method for detection of multiple positioning signals, comprising:
detecting a first positioning signal using non-coherent integration over blocks of a received signal of a predetermined size between 1 millisecond and 14 milliseconds;
based on the first positional signal, determining the values of one or more signal detection parameters;
using the values of the signal detection parameters, detecting a second positioning signal using coherent integration.
2. A method as in claim 1 , wherein determining the values of one or more signal detection parameters includes aligning the first positioning signal relative to a navigation message embedded in the first positioning signal.
3. A method as in claim 1 , wherein determining the values of one or more signal detection parameters includes determining an oscillator frequency.
4. A method as in claim 1 , wherein determining the values of one or more signal detection parameters include determining an oscillator phase acceleration.
5. A method as in claim 1 , wherein the non-coherent integration is performed by operating on correlation values computed based on the predetermined size blocks of a received signal.
6. A method as in claim 5 , further comprising combining the correlation values into a single value.
7. A method as in claim 1 , wherein determining the values of one or more signal detection parameters is carried out in the frequency domain.
8. A method as in claim 1 , further comprising, prior to the coherent integration, removing the effect of a navigation message.
9. A method as in claim 8 , wherein the removing comprising doubling an estimated phase angle.
10. A method as in claim 1 further comprising recovering a time stamp from the first positioning signal.