Multi-clock matched filter for receiving signals with multipath
First Claim
1. An improvement, to a spread-spectrum receiver, for receiving, in a multipath environment, a spread-spectrum signal having data spread by a chip-sequence signal, with each chip of the chip-sequence signal having a chip duration, with the spread-spectrum signal arriving from a plurality of paths from the multipath environment, comprising:
- a clock-signal generator for generating a clock signal, with the clock signal, during a chip duration, having a plurality of phases, with a number of phases of the plurality of phases at least equal to a number of paths of the plurality of paths;
an analog-to-digital converter for sampling the spread-spectrum signal to generate, during the chip duration, a plurality of chip samples, with a number of chip samples in the plurality of chip samples at least equal to the number of phases in the plurality of phases, said analog-to-digital converter, responsive to each chip sample of the plurality of chip samples, for converting each chip sample to a digital-chip sample, thereby generating a plurality of digital-chip samples;
a plurality of signal registers, coupled to said analog-to-digital converter, for storing the plurality of digital-chip samples;
a plurality of gates, coupled between said plurality of signal registers, respectively, and said analog-to-digital converter, each of said plurality of gates responsive to a set of phase signals, respectively, from a multiplicity of sets of phase signals, for passing a respective number of the plurality of digital-chip samples into a respective signal register of the plurality of signal registers;
a signal-register multiplexer, coupled to each of the plurality of signal registers, said signal-register multiplexer responsive to a register-select signal, for selecting a respective signal register from the plurality of signal registers;
a matched filter, coupled to said signal-register multiplexer, and having an impulse response matched to the spread-spectrum signal, for detecting an early portion, a punctual portion and a late portion of each chip embedded in the spread-spectrum signal for each path of the plurality of paths, respectively;
a RAKE-timing generator for generating a plurality of path-select signals corresponding to the plurality of paths from the multipath environment;
a plurality of delay-locked-loop (DLL) path-tracking circuits, with each DLL path-tracking circuit responsive to a respective path-select signal of the plurality of path-select signals, for gating the early portion and the late portion, corresponding to a respective path, of a detected spread-spectrum signal, into the respective DLL path-tracking circuit, and for generating a DLL signal of a plurality of DLL signals; and
a plurality of DLL multiplexers coupled to said clock-signal generator, to said plurality of DLL path-tracking circuits, and to said plurality of gates, respectively, each DLL multiplexer of said plurality of DLL multiplexers, responsive to a respective DLL signal from a respective DLL path-tracking circuit, for passing a respective set of phases of the plurality of phases from said clock-signal generator to a respective gate of said plurality of gates, with said plurality of DLL multiplexers thereby generating a multiplicity of sets of phase signals, respectively.
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Accused Products
Abstract
A multi-clock matched filter for receiving signals with multipath. The signals may be modulated with a spread-spectrum spreading sequence, or other analog or digital signal. A number of signal registers store digital samples of the received signal. The gating of digital samples into each of the signal registers is controlled by a separate clock timing. The timing sequence may be derived from a common clock. A multiplexer sequentially selects each of the signal registers, and passes the respective content of each signal register to a matched filter. A number of delay-locked-loop circuits track each of the multipath signals, and generate the timing sequence for gating signal registers.
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Citations
12 Claims
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1. An improvement, to a spread-spectrum receiver, for receiving, in a multipath environment, a spread-spectrum signal having data spread by a chip-sequence signal, with each chip of the chip-sequence signal having a chip duration, with the spread-spectrum signal arriving from a plurality of paths from the multipath environment, comprising:
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a clock-signal generator for generating a clock signal, with the clock signal, during a chip duration, having a plurality of phases, with a number of phases of the plurality of phases at least equal to a number of paths of the plurality of paths; an analog-to-digital converter for sampling the spread-spectrum signal to generate, during the chip duration, a plurality of chip samples, with a number of chip samples in the plurality of chip samples at least equal to the number of phases in the plurality of phases, said analog-to-digital converter, responsive to each chip sample of the plurality of chip samples, for converting each chip sample to a digital-chip sample, thereby generating a plurality of digital-chip samples; a plurality of signal registers, coupled to said analog-to-digital converter, for storing the plurality of digital-chip samples; a plurality of gates, coupled between said plurality of signal registers, respectively, and said analog-to-digital converter, each of said plurality of gates responsive to a set of phase signals, respectively, from a multiplicity of sets of phase signals, for passing a respective number of the plurality of digital-chip samples into a respective signal register of the plurality of signal registers; a signal-register multiplexer, coupled to each of the plurality of signal registers, said signal-register multiplexer responsive to a register-select signal, for selecting a respective signal register from the plurality of signal registers; a matched filter, coupled to said signal-register multiplexer, and having an impulse response matched to the spread-spectrum signal, for detecting an early portion, a punctual portion and a late portion of each chip embedded in the spread-spectrum signal for each path of the plurality of paths, respectively; a RAKE-timing generator for generating a plurality of path-select signals corresponding to the plurality of paths from the multipath environment; a plurality of delay-locked-loop (DLL) path-tracking circuits, with each DLL path-tracking circuit responsive to a respective path-select signal of the plurality of path-select signals, for gating the early portion and the late portion, corresponding to a respective path, of a detected spread-spectrum signal, into the respective DLL path-tracking circuit, and for generating a DLL signal of a plurality of DLL signals; and a plurality of DLL multiplexers coupled to said clock-signal generator, to said plurality of DLL path-tracking circuits, and to said plurality of gates, respectively, each DLL multiplexer of said plurality of DLL multiplexers, responsive to a respective DLL signal from a respective DLL path-tracking circuit, for passing a respective set of phases of the plurality of phases from said clock-signal generator to a respective gate of said plurality of gates, with said plurality of DLL multiplexers thereby generating a multiplicity of sets of phase signals, respectively. - View Dependent Claims (2, 3, 4)
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5. An improvement, to a spread-spectrum receiver, for receiving, in a multipath environment, a spread-spectrum signal having data spread by a chip-sequence signal, with each chip of the chip-sequence signal having a chip duration, with the spread-spectrum signal arriving from a plurality of paths from the multipath environment, comprising:
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clock-signal means for generating a clock signal, with the clock signal, during a chip duration, having a plurality of phases, with a number of phases of the plurality of phases at least equal to a number of paths of the plurality of paths; converter means for sampling the spread-spectrum signal to generate, during the chip duration, a plurality of chip samples, with a number of chip samples in the plurality of chip samples at least equal to the number of phases in the plurality of phases, said converter means, responsive to each chip sample of the plurality of chip samples, for converting each chip sample to a digital-chip sample; register means for storing a plurality of digital-chip samples; gate means coupled between said register means and said converter means, said gate means responsive to a set of phase signals from a multiplicity of sets of phase signals, for passing a respective number of the plurality of digital-chip samples into a respective signal register of the register means; signal-multiplexer means coupled to said register means, said signal-multiplexer means responsive to a register-select signal, for selecting a respective signal register from said register means; matched-filter means, coupled to said signal-multiplexer means and having an impulse response matched to the spread-spectrum signal, for detecting an early portion, a punctual portion and a late portion of each chip embedded in the spread-spectrum signal for each path of the plurality of paths, respectively; RAKE generator means for generating a plurality of path-select signals corresponding to the plurality of paths from the multipath environment; delay-locked-loop (DLL) means, responsive to a respective path-select signal from the plurality of path-select signals, for gating the early portion and the late portion, corresponding to a respective path, of a detected spread-spectrum signal, into the DLL means, and for generating a DLL signal of a plurality of DLL signals; and DLL multiplexer means, coupled to said clock-signal means, to said DLL means, and to said gate means, and responsive to a respective DLL signal from said DLL means, for passing a respective set of phases of the plurality of sets of phases from said clock-signal means to said gate means, with said DLL multiplexer means thereby generating a multiplicity of sets of phase signals, respectively. - View Dependent Claims (6, 7, 8)
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9. A method for improving a spread-spectrum receiver for receiving, from a multipath environment, a spread-spectrum signal having data spread by a chip-sequence signal, with each chip of the chip-sequence signal having a chip duration, with the spread-spectrum signal arriving from a plurality of paths from the multipath environment, comprising the steps of:
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generating a clock signal, with the clock signal, during a chip duration, having a plurality of phases, with a number of phases of the plurality of phases at least equal to a number of paths of the plurality of paths; sampling the spread-spectrum signal to generate, during the chip duration, a plurality of chip samples, with a number of chip samples in the plurality of chip samples at least equal to the number of phases in the plurality of phases; converting, in response to each chip sample of the plurality of chip samples, each chip sample to a digital-chip sample; storing a plurality of digital-chip samples in a plurality of signal registers; passing, through a plurality of gates, a respective number of the plurality of digital-chip samples into a respective signal register of the plurality of signal registers; selecting a respective signal register from the plurality of signal registers; detecting an early portion, a punctual portion and a late portion of each chip embedded in the spread-spectrum signal for each path of the plurality of paths, respectively; generating a plurality of path-select signals corresponding to the plurality of paths from the multipath environment; gating the early portion and the late portion, corresponding to a respective path, of the detected spread-spectrum signal, for generating a DLL signal of a plurality of DLL signals; and passing, in response to a respective DLL signal, a respective set of phases of the plurality of phases to a respective gate of said plurality of gates. - View Dependent Claims (10, 11, 12)
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Specification