Processing a GNSS signal based on doppler estimates
Assigneeu-blox AG
InventorsZhenlan Cheng, Robert Lluis Garcia, Maxim Koehler
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Abstract
A method and apparatus are provided for processing a GNSS signal received at a receiver. The GNSS signal may be tracked in different ways in two or more respective operation modes. A first epoch is processed according to a first operation mode. In this mode, a carrier phase of a local carrier signal is controlled to track the carrier phase of the GNSS signal using a phase locked loop. A second epoch is processed according to a second operation mode. In this operation mode, the carrier phase is controlled based at least in part on at least one Doppler estimate. The at least one Doppler estimate depends on inertial measurements made at the receiver.
Claims15
A method of processing a Global Navigation Satellite System (GNSS) signal received at a receiver, comprising:
- for a first epoch:
- obtaining first samples of the GNSS signal;
- generating a local carrier signal;
- mixing the local carrier signal with the first samples to generate first carrier-free signal samples;
- generating a local spreading code;
- correlating the first carrier-free signal samples with the local spreading code to generate first complex-valued correlation results for the first epoch;
- and
- processing the first complex-valued correlation results to produce at least one of:
- a first indication of whether the GNSS signal is detected or not;
- and a first GNSS measurement for the first epoch,
- wherein, during the mixing for the first epoch, a carrier phase of the local carrier signal is controlled to track a carrier phase of the GNSS signal using a phase locked loop, and
- for a second epoch:
- obtaining second samples of the GNSS signal,
- obtaining at least one Doppler estimate for the GNSS signal, wherein the at least one Doppler estimate is based on inertial measurements made at the receiver,
- mixing the local carrier signal with the second samples to generate second carrier-free signal samples;
- correlating the second carrier-free signal samples with the local spreading code to generate second complex-valued correlation results for the second epoch;
- and
- processing the second complex-valued correlation results to produce at least one of:
- a second indication of whether the GNSS signal is detected or not;
- and a second GNSS measurement for the second epoch,
- wherein, during the mixing for the second epoch, the carrier phase of the local carrier signal is controlled based at least in part on the at least one Doppler estimate.
A non-transitory computer-readable medium comprising computer program code that, when executed by one or more computing devices, causes the one or more computing devices to perform operations comprising:
- for a first epoch:
- obtaining first samples of a Global Navigation Satellite System (GNSS) signal;
- generating a local carrier signal;
- mixing the local carrier signal with the first samples to generate first carrier-free signal samples;
- generating a local spreading code;
- correlating the first carrier-free signal samples with the local spreading code to generate first complex-valued correlation results for the first epoch;
- and
- processing the first complex-valued correlation results to produce at least one of:
- a first indication of whether the GNSS signal is detected or not;
- and a first GNSS measurement for the first epoch,
- wherein, during the mixing for the first epoch, a carrier phase of the local carrier signal is controlled to track a carrier phase of the GNSS signal using a phase locked loop, and
- for a second epoch:
- obtaining second samples of the GNSS signal,
- obtaining at least one Doppler estimate for the GNSS signal, wherein the at least one Doppler estimate is based on inertial measurements made at a receiver,
- mixing the local carrier signal with the second samples to generate second carrier-free signal samples;
- correlating the second carrier-free signal samples with the local spreading code to generate second complex-valued correlation results for the second epoch;
- and
- processing the second complex-valued correlation results to produce at least one of:
- a second indication of whether the GNSS signal is detected or not;
- and a second GNSS measurement for the second epoch,
- wherein, during the mixing for the second epoch, the carrier phase of the local carrier signal is controlled based at least in part on the at least one Doppler estimate.
A Global Navigation Satellite System (GNSS) receiver configured to process a GNSS signal, the GNSS receiver comprising at least one processor and memory comprising instructions that, when executed by the at least one processor, causes the GNSS receiver to perform operations comprising:
- for a first epoch:
- obtain first samples of the GNSS signal;
- generate a local carrier signal;
- mix the local carrier signal with the first samples to generate first carrier-free signal samples;
- generate a local spreading code;
- correlate the first carrier-free signal samples with the local spreading code to generate first complex-valued correlation results for the first epoch;
- and
- process the first complex-valued correlation results to produce at least one of:
- a first indication of whether the GNSS signal is detected or not;
- and a first GNSS measurement for the first epoch,
- wherein, during the mixing for the first epoch, a carrier phase of the local carrier signal is controlled to track a carrier phase of the GNSS signal using a phase locked loop, and
- for a second epoch:
- obtain second samples of the GNSS signal,
- obtain at least one Doppler estimate for the GNSS signal, wherein the at least one Doppler estimate is based on inertial measurements made at the receiver,
- mix the local carrier signal with the second samples to generate second carrier-free signal samples;
- correlate the second carrier-free signal samples with the local spreading code to generate second complex-valued correlation results for the second epoch;
- and
- process the second complex-valued correlation results to produce at least one of:
- a second indication of whether the GNSS signal is detected or not;
- and a second GNSS measurement for the second epoch,
- wherein, during the mixing for the second epoch, the carrier phase of the local carrier signal is controlled based at least in part on the at least one Doppler estimate.
Dependencies are inferred from the claim text.