Voice and data exchange over a packet based network with timing recovery
First Claim
1. A method for timing recovery of a signal having a data rate, the method comprising:
- sampling the signal at a sampling rate to produce a plurality of samples;
estimating a phase error between the data rate and the sampling rate;
estimating a frequency error between the data rate and the sampling rate, during an estimation phase;
combining the estimated phase error with the estimated frequency error; and
adjusting the sampling rate as a function of the combined phase and frequency error during an application phase, wherein the estimation phase and the application phase are non-overlapping in time.
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Accused Products
Abstract
A signal processing system which discriminates between voice signals and data signals modulated by a voiceband carrier. The signal processing system includes a voice exchange, a data exchange and a call discriminator. The voice exchange is capable of exchanging voice signals between a switched circuit network and a packet based network. The signal processing system also includes a data exchange capable of exchanging data signals modulated by a voiceband carrier on the switched circuit network with unmodulated data signal packets on the packet based network. The data exchange is performed by demodulating data signals from the switched circuit network for transmission on the packet based network, and modulating data signal packets from the packet based network for transmission on the switched circuit network. The call discriminator is used to selectively enable the voice exchange and data exchange.
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Citations
18 Claims
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1. A method for timing recovery of a signal having a data rate, the method comprising:
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sampling the signal at a sampling rate to produce a plurality of samples;
estimating a phase error between the data rate and the sampling rate;
estimating a frequency error between the data rate and the sampling rate, during an estimation phase;
combining the estimated phase error with the estimated frequency error; and
adjusting the sampling rate as a function of the combined phase and frequency error during an application phase, wherein the estimation phase and the application phase are non-overlapping in time. - View Dependent Claims (2, 3, 4, 5, 6, 12, 13)
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7. A system for timing recovery of a signal having a data rate, the method comprising:
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a sampler configured to sample the signal at a sampling rate to produce a plurality of samples;
a timing error estimator configured to estimate a phase error between the data rate and the sampling rate;
a frequency offset estimator configured to estimate a frequency error between the data rate and the sampling rate, during an estimation phase;
a combiner configured to combine the estimated phase error with the estimated frequency error; and
a clock adjuster which adjusts the sampling rate of the sampler as a function of the combined phase and frequency error, wherein the estimation phase and the application phase are non-overlapping in time. - View Dependent Claims (8, 9, 10, 11)
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14. A data transmission system, comprising:
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a telephony device for outputting a signal having a data rate; and
a data exchange coupled to the telephony device, the data exchange having, a sampler configured to sample the signal at a sampling rate to produce a plurality of samples, a timing error estimator configured to estimate a phase error between the data rate and the sampling rate, a frequency offset estimator configured to estimate a frequency error between the data rate and the sampling rate, during an estimation phase, a combiner configured to combine the estimated phase error with the estimated frequency error, and a clock adjuster which adjusts the sampling rate of the sampler as a function of the combined phase and frequency error, wherein the estimation phase and the application phase are non-overlapping in time. - View Dependent Claims (15, 16, 17, 18)
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Specification