Detecting Lack of Movement to Aid GNSS Receivers
AssigneeTexas Instruments Incorporated
InventorsDeric W. Waters, June Chul Roh, Sandeep Rao
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Abstract
Embodiments of the invention provide a method of detecting movement to aid GNSS receivers. By detecting when the user is stationary, the Doppler frequency estimation can be corrected or the SNR can be boosted more both of which lead to improved performance. The embodiments allow a GNSS receiver to process signals in when the signal level would otherwise be too low—for example indoors. The embodiments can improve performance when one or more satellites are temporarily blocked but one or more satellites are still being tracked.
Claims38
A method for estimating the clock drift, said method comprising:
- receiving a signal from a satellite;
- estimating a Doppler frequency of said satellite;
- receiving an assistance Doppler frequency from an aiding source that is given under the assumption that said user is stationary;
- comparing said estimated Doppler frequency to said assistance Doppler frequency when said user is stationary;
- and
- using the difference in the two Doppler frequencies to estimate clock drift.
An apparatus comprising:
- a processor for processing a signal;
- a clock drift estimator coupled to said processor, for computing an estimate of a clock drift;
- and
- an aiding source coupled to processor for providing Doppler information;
A method for reacquiring satellite signals quickly, said method comprising:
- estimating a pseudorange of at least one satellite;
- estimating a user position;
- and
- receiving a signal from at least one satellite.
A method of adjusting a bandwidth of a receiver, said method comprising:
- combining a plurality of correlator engine outputs;
- sensing a plurality of user dynamics;
- and
- adjusting said bandwidth.
A method of reducing a search space for a Doppler frequency of a satellite signal, said method comprising:
- a sensor module sensing a plurality of user dynamics using a plurality of low-cost sensors,
- searching over a plurality of time delays and Doppler frequency hypotheses around an initial estimate of each;
- and
- limit searching to a small number of Doppler frequency hypotheses around a given Doppler frequency.
Dependencies are inferred from the claim text.