Communication signal symbol timing error detection and recovery
First Claim
1. An apparatus comprising:
- a band-edge filtering arrangement operable to receive as inputs samples of a received communication signal, and to provide a filtered output signal comprising band edges of the samples, the received communication signal comprising symbols and the samples comprising samples of the communication signal according to receive symbol timing;
a down converter operatively coupled to the band-edge filtering arrangement and operable to convert the filtered output signal to baseband by multiplying the filtered output signal by quadrature carrier waveforms; and
a symbol timing phase error calculator operatively coupled to the down converter and operable to calculate a phase error of the receive symbol timing based on the down converted baseband signal, the symbol timing phase error calculator determining a sign of a product of the filtered output signal and one of the quadrature carrier waveforms, and comprising a multiplier for multiplying the product of the filtered output signal and another of the quadrature carrier waveforms by the determined sign.
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Accused Products
Abstract
Communication signal symbol timing error detection and recovery apparatus and techniques are disclosed. A communication signal that includes symbols is sampled according to receive symbol timing. The samples are band-edge filtered to provide a filtered output signal including band edges of the samples. The filtered output signal is converted to baseband, and a phase error of the receive symbol timing is calculated based on the down converted baseband signal. The communication signal may include symbols associated with quadrature channels, in which case a respective filtered output signal that includes band edges of samples associated with each quadrature channel may be down converted. The down converted baseband signals may then be separated into upper and lower band-edge signals, which are used to calculate a phase error of the receive symbol timing. The upper and lower band-edge signals may also be used for other purposes, such as slope equalization and/or carrier synchronization.
20 Citations
20 Claims
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1. An apparatus comprising:
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a band-edge filtering arrangement operable to receive as inputs samples of a received communication signal, and to provide a filtered output signal comprising band edges of the samples, the received communication signal comprising symbols and the samples comprising samples of the communication signal according to receive symbol timing; a down converter operatively coupled to the band-edge filtering arrangement and operable to convert the filtered output signal to baseband by multiplying the filtered output signal by quadrature carrier waveforms; and a symbol timing phase error calculator operatively coupled to the down converter and operable to calculate a phase error of the receive symbol timing based on the down converted baseband signal, the symbol timing phase error calculator determining a sign of a product of the filtered output signal and one of the quadrature carrier waveforms, and comprising a multiplier for multiplying the product of the filtered output signal and another of the quadrature carrier waveforms by the determined sign. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method comprising:
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band-edge filtering samples of a received communication signal to provide a filtered output signal comprising band edges of the samples, the received communication signal comprising symbols and the samples comprising samples of the communication signal according to receive symbol timing; down converting the filtered output signal to baseband by multiplying the filtered output signal by quadrature carrier waveforms; and calculating a phase error of the receive symbol timing based on the down converted baseband signal by determining a sign of a product of the filtered output signal and one of the quadrature carrier waveforms, and multiplying the product of the filtered output signal and another of the quadrature carrier waveforms by the determined sign. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19)
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20. A non-transitory computer-readable medium storing instructions which when executed perform the method comprising:
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band-edge filtering samples of a received communication signal to provide a filtered output signal comprising band edges of the samples, the received communication signal comprising symbols and the samples comprising samples of the communication signal according to receive symbol timing; down converting the filtered output signal to baseband by multiplying the filtered output signal by quadrature carrier waveforms; and calculating a phase error of the receive symbol timing based on the down converted baseband signal by determining a sign of a product of the filtered output signal and one of the quadrature carrier waveforms, and multiplying the product of the filtered output signal and another of the quadrature carrier waveforms by the determined sign.
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Specification