Adaptive clock recovery with step-delay pre-compensation
First Claim
1. An adaptive clock recovery (ACR) system for a receiver, the ACR system comprising:
- an ACR subsystem that generates a reference phase signal from an input phase signal representing packet delay values corresponding to arrival times of packets at the receiver;
a step-delay detection and measurement (D/M) subsystem that compares the input phase signal to the reference phase signal to detect occurrence of a step-delay in the packet arrival times and determine direction and magnitude of the detected step-delay; and
a step-delay pre-compensation component that adjusts the input phase signal, upstream of the ACR subsystem, based on the determined direction and magnitude of the detected step-delay.
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Abstract
An adaptive clock recovery (ACR) subsystem processes an input phase signal indicative of jittery packet arrival times to generate a relatively smooth and bounded output phase signal that can be used to generate a relatively stable recovered clock signal. The input phase signal is also processed to detect and measure step-delays corresponding, for example, to path changes in the network routing of the packets. Step-delay pre-compensation is performed, in which the input phase signal is phase-adjusted, upstream of the ACR subsystem, based on the sign and magnitude of each detected step-delay. As a result, the ACR subsystem is substantially oblivious to the existence of such step-delays.
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Citations
19 Claims
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1. An adaptive clock recovery (ACR) system for a receiver, the ACR system comprising:
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an ACR subsystem that generates a reference phase signal from an input phase signal representing packet delay values corresponding to arrival times of packets at the receiver; a step-delay detection and measurement (D/M) subsystem that compares the input phase signal to the reference phase signal to detect occurrence of a step-delay in the packet arrival times and determine direction and magnitude of the detected step-delay; and a step-delay pre-compensation component that adjusts the input phase signal, upstream of the ACR subsystem, based on the determined direction and magnitude of the detected step-delay. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A receiver-implemented method for recovering a clock signal at a receiver in a packet system, the method comprising:
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generating a reference phase signal from an input phase signal representing packet delay values corresponding to arrival times of packets at the receiver; comparing the input phase signal to the reference phase signal to detect the occurrence of a step-delay in the packet arrival times and determine direction and magnitude of the detected step-delay; and adjusting the input phase signal, upstream of the generation of the reference phase signal, based on the determined direction and magnitude of the detected step-delay.
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Specification