Symbol timing recovery based on complex sample magnitude
First Claim
1. In a digital communication receiver, a method of recovering symbol timing from an analog signal configured as a stream of symbols, said method comprising the steps of:
- generating a clock signal which defines symbol timing;
sampling said analog signal in response to said clock signal to generate less than two complex samples for each symbol;
separating magnitude attributes of said less than two complex samples for each symbol from phase attributes of said less than two complex samples for each symbol so that said magnitude attributes are substantially insensitive to phase changes; and
adjusting said symbol timing defined by said clock signal in response to at least a portion of said magnitude attributes.
5 Assignments
0 Petitions
Accused Products
Abstract
A digital communication receiver (10) takes one complex sample (20) of a baseband analog signal (12) per symbol. A rectangular to polar converter (26) separates phase attributes of the complex samples from magnitude attributes. A phase processor (28) identifies clock adjustment opportunities which occur when relatively large phase changes take place between consecutive symbols. A magnitude processor (32) influences symbol timing only during clock adjustment opportunities. The magnitude processor (32) advances symbol timing in a phase locked loop when decreasing magnitude changes are detected during clock adjustment opportunities and retards symbol timing when increasing magnitude changes are detected during clock adjustment opportunities. An interpolator (66) may be used to estimate magnitude values between samples so that magnitude change is determined between sampled magnitude values and estimated magnitude values.
36 Citations
24 Claims
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1. In a digital communication receiver, a method of recovering symbol timing from an analog signal configured as a stream of symbols, said method comprising the steps of:
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generating a clock signal which defines symbol timing; sampling said analog signal in response to said clock signal to generate less than two complex samples for each symbol; separating magnitude attributes of said less than two complex samples for each symbol from phase attributes of said less than two complex samples for each symbol so that said magnitude attributes are substantially insensitive to phase changes; and adjusting said symbol timing defined by said clock signal in response to at least a portion of said magnitude attributes. - View Dependent Claims (5)
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2. In a digital communication receiver, a method of recovering symbol timing from an analog signal configured as a stream of symbols, said method comprising the steps of:
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generating a clock signal which defines symbol timing; sampling said analog signal in response to said clock signal to generate a complex sample for each symbol; separating magnitude attributes of said complex samples from phase attributes of said complex samples so that said magnitude attributes are substantially insensitive to phase changes; identifying clock adjustment opportunities in response to said phase attributes of said complex samples; and enabling at least a portion of said magnitude attributes which are approximately coincident with said clock adjustment opportunities to adjust said symbol timing; and adjusting said symbol timing defined by said clock signal in response to said portion of said magnitude attributes. - View Dependent Claims (3, 4)
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6. In a digital communication receiver, a method of recovering symbol timing from an analog signal configured as a stream of symbols, said method comprising the steps of:
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generating a clock signal which defines symbol timing; sampling said analog signal in response to said clock signal to generate a complex sample for each symbol; identifying clock adjustment opportunities in response to phase relationships exhibited by said complex samples; and adjusting said symbol timing defined by said clock signal in response to magnitude relationships exhibited by said complex samples at approximately said identified clock adjustment opportunities. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A symbol synchronizer for recovering symbol timing in a digital communication receiver which receives an analog signal configured as a stream of symbols, said symbol synchronizer comprising:
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an oscillator for generating a clock signal which defines symbol timing; an analog-to-digital converter, coupled to said oscillator, for sampling said analog signal to generate a complex sample for each symbol; a phase processor, coupled to said converter, for identifying clock adjustment opportunities in response to phase relationships exhibited by said complex samples; and a magnitude processor, coupled to said converter, said phase processor, and said oscillator, for adjusting said symbol timing defined by said clock signal in response to magnitude relationships exhibited by said complex samples at approximately said identified clock adjustment opportunities. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification