Compensation for phase errors caused by clock jitter in a CDMA communication system
First Claim
1. A spread spectrum communication system, comprising:
- a data spreading circuit for spreading data by a PN sequence and filtering the spread data, a clock producing circuit for generating an internal clock signal based on a reference clock signal, and an interpolation circuit for performing interpolation of filtered spread data formed by the data spreading circuit to determine an adjusted spread data value that compensates for a phase error caused by jitter in the internal clock signal.
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Accused Products
Abstract
A CDMA reverse link has a system for providing compensation for phase errors caused by clock jitter in a CDMA reverse link. After filtering, data spread by a pilot PN sequence is supplied to a shift register that produces several data samples for sequential cycles of an internal clock. A memory stores compensation factors representing the clock jitter, pre-calculated for each of the internal clock cycles. A counter counts the internal clock cycles to provide the memory with an address signal indicating a memory location that stores the compensation factor for a current internal clock cycle. Based on the data samples and the compensation factor, an interpolator performs an interpolation algorithm to determine an adjusted spread data value that compensates for phase errors caused by jitter in the internal clock.
19 Citations
20 Claims
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1. A spread spectrum communication system, comprising:
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a data spreading circuit for spreading data by a PN sequence and filtering the spread data, a clock producing circuit for generating an internal clock signal based on a reference clock signal, and an interpolation circuit for performing interpolation of filtered spread data formed by the data spreading circuit to determine an adjusted spread data value that compensates for a phase error caused by jitter in the internal clock signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. In a CDMA reverse link having a clock generator for producing an internal clock signal based on a reference clock signal, a system for compensating for phase errors caused by jitter in the internal clock signal, comprising:
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a sampling circuit responsive to digital data spread by a PN sequence and filtered by a filter for producing spread data samples for sequential internal clock cycles, a memory for storing compensation factors representing the internal clock jitter, and an interpolator responsive to the spread data samples and the compensation factors for performing interpolation of filtered spread data to determine adjusted spread data values that compensate for the phase errors caused by the internal clock jitter. - View Dependent Claims (12, 13, 14, 15)
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16. In a spread spectrum system having an internal clock generator for producing an internal clock signal based on a reference signal, a method of compensating for phase errors caused by jitter in the internal clock signal, comprising the steps of:
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sampling digital data spread by a PN sequence and filtered by a filter to produce spread data samples for several sequential internal clock cycles, and interpolating the spread data samples using compensation factors to determine an adjusted spread data value that compensates for the phase errors caused by the clock jitter. - View Dependent Claims (17, 18, 19, 20)
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Specification