Discriminator system for timing error detection in presence and absence of multipath conditions
First Claim
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1. An apparatus, comprising:
- a multipath discriminator configured to generate a first tracking error that estimates a phase difference between a received signal and a local reference signal, and that corresponds to the received signal (i) in the presence of multipath interference and/or (ii) at low signal level;
a line-of-sight (LOS) discriminator configured to generate a second tracking error that estimates the phase difference between the received signal and the local reference signal;
a multipath switch configured to;
detect (i) a presence of multipath interference in the received signal and/or (ii) a low signal level of the received signal as compared to a threshold, andindicate whether either (i) the first tracking error is to be utilized or (ii) the second tracking error is to be utilized;
a code tracking loop configured to utilize the first tracking error or the second tracking error, as indicated by the multipath switch, to adjust the synchronization between the local reference signal and the received signal in an attempt to reduce code phase error; and
a plurality of correlators configured to correlate the received signal with a plurality of delayed versions of the local reference signal, the plurality of correlators generating at least an early correlation signal and a prompt correlation signal.
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Abstract
In a code tracking loop, a multipath discriminator is configured to generate a first tracking error corresponding to a received signal in the presence of multipath interference and/or at low signal level. A line-of-sight (LOS) discriminator is configured to generate a second tracking error corresponding to the received signal. A multipath switch is configured to i) detect the presence of multipath interference in the received signal and/or a low signal level of the received signal compared to a threshold, and ii) indicate whether the first tracking error or the second tracking error is to be utilized.
22 Citations
18 Claims
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1. An apparatus, comprising:
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a multipath discriminator configured to generate a first tracking error that estimates a phase difference between a received signal and a local reference signal, and that corresponds to the received signal (i) in the presence of multipath interference and/or (ii) at low signal level; a line-of-sight (LOS) discriminator configured to generate a second tracking error that estimates the phase difference between the received signal and the local reference signal; a multipath switch configured to; detect (i) a presence of multipath interference in the received signal and/or (ii) a low signal level of the received signal as compared to a threshold, and indicate whether either (i) the first tracking error is to be utilized or (ii) the second tracking error is to be utilized; a code tracking loop configured to utilize the first tracking error or the second tracking error, as indicated by the multipath switch, to adjust the synchronization between the local reference signal and the received signal in an attempt to reduce code phase error; and a plurality of correlators configured to correlate the received signal with a plurality of delayed versions of the local reference signal, the plurality of correlators generating at least an early correlation signal and a prompt correlation signal. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method, comprising:
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detecting (i) whether multipath interference is present in a received signal and/or (ii) whether a signal level of the received signal is low as compared to a threshold; correlating the received signal with a plurality of delayed versions of a local reference signal to generate at least an early correlation signal and a prompt correlation signal; generating, with a multipath discriminator, a first tracking error that estimates a phase difference between the received signal and the local reference signal when (i) multipath interference in the received signal is detected and/or (ii) when the signal level of the received signal is low as compared to the threshold; generating, with a line-of-sight (LOS) discriminator, a second tracking error that estimates a phase difference between the received signal and the local reference signal when (i) multipath interference in the received signal is not detected and/or when (ii) the signal level of the received signal is high as compared to the threshold; and utilizing the first tracking error or the second tracking error to adjust synchronization between the local reference signal and the received signal in an attempt to reduce code phase error based on at least one of (i) whether multipath interference in the received signal is detected, and/or (ii) whether the signal level of the received signal is low as compared to the threshold. - View Dependent Claims (8, 9, 10, 11, 12)
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13. An apparatus, comprising:
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a multipath discriminator configured to generate a first timing error that estimates a phase difference between a received signal and a local reference signal, and that corresponds to the received signal (i) in the presence of multipath interference and/or (ii) at low signal level; a line-of-sight (LOS) discriminator configured to generate a second timing error that estimates the phase difference between the received signal and the local reference signal; a multipath switch configured to; detect (i) a presence of multipath interference in the received signal and/or (ii) a low signal level of the received signal as compared to a threshold, and indicate whether the first timing error or the second timing error is to be utilized; and a code tracking loop configured to utilize the first timing error or the second timing error, as indicated by the multipath switch, to adjust the synchronization between the local reference signal and the received signal in an attempt to reduce code phase error; and a plurality of correlators configured to correlate the received signal with a plurality of delayed versions of the local reference signal, the plurality of correlators generating at least an early correlation signal and a prompt correlation signal. - View Dependent Claims (14, 15, 16, 17, 18)
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Specification