Method and apparatus for fast acquisition and low SNR tracking in satellite positioning system receivers
First Claim
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1. An enhanced digital channel processor for a satellite positioning system (SATPS) receiver, comprising:
- a memory processor having a storage device, wherein, during a low SNR and/or fast acquisition mode, said memory processor accumulates samples of a down-converted SATPS signal that have sequential ordinal positions that are repeated within each of a plurality of pseudo-random noise (PRN) code repetition periods in an integration period, stores in said storage device a separate accumulated sum for each ordinal position of each code repetition period, and plays the sums back at a substantially accelerated rate.
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Abstract
A satellite positioning system (SATPS) receiver has a mix of standard and enhanced digital channel processors. The standard digital channel processors perform continuous tracking. During a low SNR and/or fast acquisition mode, the enhanced digital channel processor accumulates samples of a SATPS signal that are identically positioned within corresponding PRN code repetition periods, and plays back the stored accumulated values of the samples in an integration period to a correlation section for correlation with a locally generated PRN code.
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Citations
41 Claims
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1. An enhanced digital channel processor for a satellite positioning system (SATPS) receiver, comprising:
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a memory processor having a storage device, wherein, during a low SNR and/or fast acquisition mode, said memory processor accumulates samples of a down-converted SATPS signal that have sequential ordinal positions that are repeated within each of a plurality of pseudo-random noise (PRN) code repetition periods in an integration period, stores in said storage device a separate accumulated sum for each ordinal position of each code repetition period, and plays the sums back at a substantially accelerated rate. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A satellite positioning system (SATPS) receiver, comprising:
at least one enhanced digital channel processor processing input signal samples, each of said at least one enhanced digital channel processor having a memory processor which, during a low SNR and/or fast acquisition mode, accumulates samples of a down-converted SATPS signal that have sequential ordinal positions that are repeated within each of a plurality of pseudo-random noise (PRN) code repetition periods in an integration period, stores in said storage device a separate accumulated sum for each ordinal position of each code repetition period, and plays back at a substantially accelerated rate the accumulated sums for the respective sample positions of the PRN code repetition period. - View Dependent Claims (12, 13, 14, 15)
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16. A method for low SNR and/or fast acquisition and measurement for a satellite positioning system (SATPS) receiver, comprising the steps of:
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accumulating samples of a down-convened SATPS signal that have sequential ordinal positions that are repeated within each of a plurality of pseudo-random noise (PRN) code repetition periods in an integration period, stores in said storage device a separate accumulated sum for each ordinal position of each code repetition period; and
playing back at a substantially accelerated rate the accumulated sums for the respective sample positions of the PRN code repetition period. - View Dependent Claims (17, 18, 19, 20)
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21. In a system wherein an incoming signal is transmitted in successive pseudo-random noise (PRN) code repetition periods, an enhanced processor comprising:
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a memory for accumulating digital samples of said signal, wherein said samples have sequential ordinal positions that are repeated within each of a plurality of pseudo-random noise (PRN code repetition periods in an integration period, stores in said storage device a separate accumulated sum for each ordinal position of each code repetition period; and
playback apparatus for playing back the accumulated samples for each of said positions at a rate that is accelerated as compared to the rate at which said memory accumulates said samples. - View Dependent Claims (22, 23, 24)
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25. A method comprising the steps of:
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receiving an incoming signal that is transmitted in successive pseudo-random noise (PRN) code repetition periods;
accumulating digital samples of said signal, wherein said samples have sequential ordinal positions that are repented within each of a plurality of pseudo-random noise (PRN) code repetition periods in an integration period, stores in said storage device a separate accumulated sum for each ordinal position of each code repetition period; and
playing back the accumulated samples for each of said positions at a rate that is accelerated as compared to the rate of accumulating said samples.
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26. A signal receiver for receiving a signal that is spread by a repeating signal code having a plurality of code repetition periods in an integration period, comprising:
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a memory processor for accumulating symbol values of a frequency translated representation of said signal, wherein said symbol values have sequential ordinal signal time positions that are repeated within each of said code repetition periods for providing a separate accumulated sum for each ordinal position of each code repetition period; and
a correlation section for correlating said integration period accumulation values with a locally generated replica of said signal code for determining correlations for time relationships, respectively, between said signal code and said replica code. - View Dependent Claims (27, 28, 31, 32, 33)
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29. A signal receiver for receiving a signal that is spread by a repeating signal code having a code repetition period, comprising:
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a memory processor for accumulating symbol values of a frequency translated representation of said signal, said symbol values being accumulated for repeating signal time positions, respectively, within said code repetition period during a signal integration period of more than one said code repetition period for providing integration period accumulation values corresponding to said signal time positions, respectively; and
a correlation section for correlating said integration period accumulation values with a locally generated replica of said signal code for determining correlations for time relationships, respectively, between said signal code and said replica code;
whereinthe memory processor includes an adder processor for adding newly received ones of said symbol values with accumulated ones of said symbol values according to said signal time positions; and
a comparator for compressing said accumulated symbol values into compressed values and issuing said compressed values as said integration period accumulation values; and
wherein;
said accumulated symbol values include a first symbol accumulation bit and an accumulated magnitude value for symbol accumulation bits not including said first symbol accumulation bit; and
said compressed values respectively include a first bit corresponding to said first symbol accumulation bit, a second bit depending upon said accumulated magnitude value being greater or lesser than a first threshold; and
a third bit depending upon said accumulated magnitude value being greater or lesser than a second threshold. - View Dependent Claims (30)
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34. A method for receiving a signal that is spread by a repeating signal code having a plurality of code repetition periods in an integration period, comprising:
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accumulating symbol values of a frequency translated representation of said signal, wherein said symbol values have sequential ordinal signal time positions that are repeated within each of said code repetition periods for providing a separate accumulated sum for each ordinal position of each code repetition period; and
correlating said integration period accumulation values with a locally generated replica of said signal code for determining correlations for time relationships, respectively, between said signal code and said replica code. - View Dependent Claims (35, 36, 39, 40, 41)
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37. A method for receiving a signal that is spread by a repeating signal code having a code repetition period, comprising:
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accumulating symbol values of a frequency translated representation of said signal, said symbol values being accumulated for repeating signal time positions, respectively, within said code repetition period during a signal integration period of more than one said code repetition period for determining integration period accumulation values corresponding to said signal time positions, respectively; and
correlating said integration period accumulation values with a locally generated replica of said signal code for determining correlations for time relationships, respectively, between said signal code and said replica code, wherein;
the step of accumulating signal symbol values includes adding newly received ones of said symbol values with accumulated ones of said symbol values according to said signal time positions;
compressing said accumulated symbol values into compressed values; and
issuing said compressed values as said integration period accumulation values;
said accumulated symbol values include a first symbol accumulation bit and an accumulated magnitude value for symbol accumulation bits not including said first symbol accumulation bit; and
said compressed values respectively include a first bit corresponding to said first symbol accumulation bit, a second bit depending upon said accumulated magnitude value being greater or lesser than a first threshold, and a third bit depending upon said accumulated magnitude value being greater or lesser than a second threshold. - View Dependent Claims (38)
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Specification