Method and apparatus for uplink clock extraction in a communication system
OwnerChandra Mauli Singh, Mohammad Akhterinventors
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Abstract
A system and method of uplink clock extraction, particularly in a satellite communication system. Jitter and sideband suppression and compensation are employed to provide an all digital method and system. A simple implementation is available using only digital components and a corresponding timing recovery algorithm. This system can operate in the absence of a timing stamp which provide better bandwidth conservation.
Claims11
A method of extracting a reference clock signal from a received analog signal, the method comprising:
- digitising the received analog signal with a sampling rate determined by a sampling clock signal;
- recovering timing signals from the digitised signal to produce a sample skipping signal;
- gating the sample skipping signal with the sample clock signal;
- generating the reference clock signal through analog synthesis of the gated signals.
The method of step 4, wherein the step of digitally cleaning includes:
- determining an error signal representative of the digitally determined phase difference between a controlled clock signal and the generated reference clock signal;
- and
- adjusting an oscillator controlling the controlled clock signal to reduce the phase difference between the controlled clock signal and the received clock signal without introducing jitter in the controlled signal;
- and
- providing the controlled clock signal as the extracted reference clock signal.
The method of step 5, wherein the step of determining an error signal further includes:
- incrementing the position of a write pointer in a circular array with every tick of the generated reference clock signal;
- decrementing the position of a read pointer in a circular array with every tick of the controlled clock signal;
- and
- generating the error signal based on the difference in the read and write pointers.
A clock signal extractor, for receiving an analog signal from a remote station and generating a reference clock signal representative of the clock of the remote station, the extractor comprising:
- a sampling clock, for generating a sampling clock signal;
- a digitiser, for receiving the analog signal from the remote station and digitising it at a sampling rate determined by the sampling clock signal;
- a timing symbol recovery unit, for receiving the digitised signal and for generating a sample skipping signal based on the digitised signal;
- a gate for gating the sample skipping signal and the sampling clock signal;
- and
- an analog synthesis unit for generating the reference clock signal based on the gated signal.
Dependencies are inferred from the claim text.