System and method for despreading in a spread spectrum matched filter
First Claim
Patent Images
1. A system for despreading a spread spectrum signal using a pseudo-noise (“
- PN”
) code, wherein the spread spectrum signal comprises a plurality of signal samples, each signal sample having an in-phase portion and a quadrature-phase portion, and wherein the PN code comprises a plurality of PN code chips, the system comprising;
a switch for selecting one of the in-phase portion and the quadrature-phase portion of a first signal sample of the plurality of signal samples;
a first multiplier coupled to the switch for multiplying the selected portion of the first signal sample with a first PN code chip of the plurality of PN code chips to obtain a first product, where the selected portion of the signal sample is first provided to an odd-even switch and is either an even portion or an odd portion of the selected portion of the first signal sample;
a second multiplier coupled to a switch for multiplying a selected portion of a second signal sample of the plurality of signal samples with the first PN code chip to obtain a second product, wherein the second signal sample succeeds the first signal sample, where the selected portion of the second signal sample is first provided to the odd-even switch and is either an even portion or an odd portion of the selected portion of the second signal sample; and
a first adder coupled to the first multiplier and the second multiplier for adding the first product with the second product to obtain a first sum.
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Abstract
Implementation of an improved matched filter system for despreading a PN code from a spread spectrum signal utilizes a matched filter system that may be broadly conceptualized as a system that optimizes the number of multipliers and adders utilized by the system in despreading a PN code from a spread spectrum signal. This lowers the power consumption of the improved matched filter system and increases the speed at which the system despreads the PN code from the spread spectrum signal.
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Citations
14 Claims
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1. A system for despreading a spread spectrum signal using a pseudo-noise (“
- PN”
) code, wherein the spread spectrum signal comprises a plurality of signal samples, each signal sample having an in-phase portion and a quadrature-phase portion, and wherein the PN code comprises a plurality of PN code chips, the system comprising;a switch for selecting one of the in-phase portion and the quadrature-phase portion of a first signal sample of the plurality of signal samples; a first multiplier coupled to the switch for multiplying the selected portion of the first signal sample with a first PN code chip of the plurality of PN code chips to obtain a first product, where the selected portion of the signal sample is first provided to an odd-even switch and is either an even portion or an odd portion of the selected portion of the first signal sample; a second multiplier coupled to a switch for multiplying a selected portion of a second signal sample of the plurality of signal samples with the first PN code chip to obtain a second product, wherein the second signal sample succeeds the first signal sample, where the selected portion of the second signal sample is first provided to the odd-even switch and is either an even portion or an odd portion of the selected portion of the second signal sample; and a first adder coupled to the first multiplier and the second multiplier for adding the first product with the second product to obtain a first sum. - View Dependent Claims (2)
- PN”
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3. A method for despreading a spread spectrum signal using a PN code, wherein the spread spectrum signal comprises a plurality of signal samples, each signal sample having an in-phase portion and a quadrature-phase portion, and wherein the PN code comprises a plurality of PN code chips, the method comprising:
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selecting one of the in-phase portion and the quadrature-phase portion of a first signal sample of the plurality of signal samples; combining the selected portion of the first signal sample with a first PN code chip of the plurality of PN code chips to obtain a first product, where the selected portion is either an odd portion or an even portion of the selected portion of the first signal sample as selected by an odd-even switch; combining the selected portion of a second signal sample of the plurality of signal samples with the first PN code chip to obtain a second product, wherein the second signal sample succeeds the first signal sample, where the selected portion is either an odd portion or an even portion of the selected portion of the second signal sample as selected by the odd-even switch; and grouping the first product with the second product to obtain a first sum. - View Dependent Claims (4, 5)
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6. A computer-readable medium having software for despreading a spread spectrum signal using a PN code, wherein the spread spectrum signal comprises a plurality of signal samples, each signal sample having an in-phase portion and a quadrature-phase portion, and wherein the PN code comprises a plurality of PN code chips, the computer-readable medium comprising:
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means for selecting one of the in-phase portion and the quadrature-phase portion of a first signal sample of the plurality of signal samples; means for selecting one of an even PN code stage and an odd PN code stage from a first PN code chip of the plurality of PN code chips; means for multiplying the selected portion of the first signal sample with the selected PN code stage to obtain a first product; and means for multiplying the selected portion of a second signal sample of the plurality of signal samples with the first PN code chip to obtain a second product, wherein the second signal sample succeeds the first signal sample; and means for adding the first product with the second product to obtain a first sum. - View Dependent Claims (7, 8)
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9. A system for despreading a spread spectrum signal using a PN code, wherein the spread spectrum signal comprises a plurality of signal sample pairs, each signal sample pair comprising an even signal sample and an odd signal sample, each signal sample having an in-phase portion and a quadrature-phase portion, and wherein the PN code comprises a plurality of PN code chips, the system comprising:
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a first switch for selecting one of the in-phase portion and the quadrature-phase portion of a first signal sample pair of the plurality of signal sample pairs; a second switch coupled to the first switch for selecting one of the even sample and the odd sample of the selected portion of the first signal sample pair; and a first multiplier coupled to the second switch for multiplying the selected portion of the selected sample of the first signal sample with a first PN code chip of the plurality of PN code chips to obtain a first product. - View Dependent Claims (10)
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11. A method for despreading a spread spectrum signal using a PN code in a matched filter, wherein the spread spectrum signal comprises a plurality of signal sample pairs, each signal sample pair comprising an even signal sample and an odd signal sample, each signal sample having an in-phase portion and a quadrature-phase portion, and wherein the PN code comprises a plurality of PN code chips, the method comprising:
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selecting one of the in-phase portion and the quadrature-phase portion of a first signal sample pair of the plurality of signal sample pairs; selecting one of the even sample and the odd sample of the selected portion of the first signal sample pair using an odd-even switch; and combining the selected portion of the selected sample of the first signal sample pair with a first PN code chip of the plurality of PN code chips to obtain a first product. - View Dependent Claims (12)
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13. A computer-readable medium having software for despreading a spread spectrum signal using a PN code, wherein the spread spectrum signal comprises a plurality of signal sample pairs, each pair comprising an even signal sample and an odd signal sample, each signal sample having an in-phase portion and a quadrature-portion, and wherein the PN code comprises a plurality of PN code chips, the computer-readable medium comprising:
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means for selecting one of the in-phase portion and the quadrature-phase portion of a first signal sample pair of the plurality of signal sample pairs; means for selecting one of the even sample and the odd sample of the selected portion of the first signal sample pair; and means for multiplying the selected portion of the selected sample of the first signal sample pair with the first PN code chip to obtain a first product. - View Dependent Claims (14)
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Specification