Synchronization of asynchronous data signals
First Claim
1. A method of synchronizing an asynchronous signal to produce a synchronized signal by stuffing the asynchronous signal in dependence upon a stuff request signal produced from a comparison of phases of the asynchronous and synchronized signals, wherein the synchronized signal comprises time division multiplexed frames each including data bits, at least one stuffing opportunity bit, and at least one overhead bit, and a plurality of said frames constitute a superframe in which at least two frames comprise different numbers of data and/or overhead bits, comprising the step of modifying the production of the stuff request signal in dependence upon a waveform having a period equal to that of the superframe thereby to distribute stuffing among said frames in the superframes.
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Accused Products
Abstract
An asynchronous data signal is synchronized by stuffing in dependence upon phase differences between the asynchronous signal and a resultant synchronized signal. The synchronized signal comprises tdm frames each including data bits and a stuffing opportunity bit, and a plurality of frames constitute a superframe in which different frames have different numbers of data bits. To compensate for the biassed timing of stuff requests which would otherwise occur relative to the frame timing in the superframes, the threshold value with which the phase difference is compared to produce the stuff requests is modified with a stepped sawtooth waveform having a period equal to that of the superframe.
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Citations
15 Claims
- 1. A method of synchronizing an asynchronous signal to produce a synchronized signal by stuffing the asynchronous signal in dependence upon a stuff request signal produced from a comparison of phases of the asynchronous and synchronized signals, wherein the synchronized signal comprises time division multiplexed frames each including data bits, at least one stuffing opportunity bit, and at least one overhead bit, and a plurality of said frames constitute a superframe in which at least two frames comprise different numbers of data and/or overhead bits, comprising the step of modifying the production of the stuff request signal in dependence upon a waveform having a period equal to that of the superframe thereby to distribute stuffing among said frames in the superframes.
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9. Synchronizing apparatus comprising:
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means responsive to a stuff request signal for stuffing an asynchronous data signal to produce a synchronized data signal comprising time division multiplexed frames each including data bits, at least one stuffing opportunity bit, and at least one overhead bit, a plurality of said frames constituting a superframe in which at least two frames contain different numbers of data and/or overhead bits; means for producing the stuff request signal in dependence upon the relative phases of the asynchronous and synchronized data signals; and modifying means for modifying the production of the stuff request signal in dependence upon a waveform having a period equal to that of the superframe thereby to distribute stuffing among said frames in the superframes. - View Dependent Claims (10, 11)
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- 12. A memthod of synchronizing an asynchronous signal to produce a synchronized signal by stuffing the asynchronous signal in dependence upon a stuff request signal produced from a comparison of phases of the asynchronous and synchronized signals, wherein the synchronized signal comprises time division multiplexed frames each including data bits, at least one stuffing opportunity bit, and at least one overhead bit, and a plurality of said frames constitute a superframe in which at least two frames comprise different numbers of data and/or overhead bits, comprising the step of modifying the production of the stuff request signal thereby to distribute stuffing among said frames in the superframes.
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14. Synchronizing apparatus comprising:
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means responsive to s stuff rrequest signal for stuffing an asynchronous data signal to produce a synchronized data signal comprising time division multiplexed frames each including data bits, at least one stuffing opportunity bit, and at least one overhead bit, a plurality of said frames constituting a superframe in which at least two frames contain different numbers of data and/or overhead bits; means for producing the stuff request signal in dependence upon the relative phases of the asynchronous and synchronized data signals; and modifying means for modifying the production of the stuff request signal thereby to distribute stuffing among said frames in the superframes. - View Dependent Claims (15)
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Specification