Two-channel fast-sequencing high-dynamics GPS navigation receiver
First Claim
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1. A navigation satellite receiver comprising:
- a first receiver channel or set of channels connected to a radio antenna for demodulating a navigation-data modulation on any of a plurality of radio transmissions from a corresponding plurality of navigation transmitters and for acquiring signals from additional transmitters;
a second receiver channel or set of channels connected to a radio antenna for sequentially tracking a plurality of radio transmissions from a corresponding plurality of transmitters;
means for sequencing the second receiver channel or channels for collecting a period of measurements sequentially from each of said plurality of transmitters that coincides with the bit times of said navigation data in which said transmissions are coherent; and
a computing means for measuring the Doppler shift or frequency error.
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Abstract
A GPS navigation receiver channel tracks satellites'"'"' Doppler frequencies sequentially during the twenty milliseconds that the signal is coherent in each bit time of the navigation data modulation. It measures frequency by differencing the angles of signal-vector sums weighted by parabolic humps, exploiting the commutativity of linear processing operations to raise the signal-to-noise ratio before the nonlinear operation phase of detection.
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Citations
3 Claims
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1. A navigation satellite receiver comprising:
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a first receiver channel or set of channels connected to a radio antenna for demodulating a navigation-data modulation on any of a plurality of radio transmissions from a corresponding plurality of navigation transmitters and for acquiring signals from additional transmitters;
a second receiver channel or set of channels connected to a radio antenna for sequentially tracking a plurality of radio transmissions from a corresponding plurality of transmitters;
means for sequencing the second receiver channel or channels for collecting a period of measurements sequentially from each of said plurality of transmitters that coincides with the bit times of said navigation data in which said transmissions are coherent; and
a computing means for measuring the Doppler shift or frequency error. - View Dependent Claims (2, 3)
computing means for tracking the phase of the signal vector measurements, wherein the phase ambiguity caused by large accelerations is resolved by using the successive Doppler-shift measurements to estimate and remove the effect of the acceleration.
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3. The receiver of claim 1, wherein:
the sequencing means switches after each data-bit time to the transmission whose next data transition occurs soonest, so that the aggregate time wasted waiting for each complete data-bit time to begin on the next transmission can never exceed the duration of one data bit over the complete sequencing cycle.
Specification