Bit synchronization circuit and central terminal for PON systems
First Claim
1. A bit synchronization circuit for synchronizing, with an internal reference clock, burst data sets received in time series order, the circuit comprising:
- a multiphase data sampling unit for converting each of the received burst data sets to multiphase data trains having phases different from each other;
a phase determination unit for detecting, from among said multiphase data trains, an optimum phase data train having the highest phase margin over the reference clock and generating a control signal indicating the optimum phase data train;
an output data selector for selectively passing, of the multiphase data trains outputted from said data sampling portion, the optimum phase data train indicated by said control signal; and
a data synchronization unit for converting the data train passed through said output data selector to a data train in synchronization with said reference clock and outputting the resulting data train, wherein said phase determination unit repeatedly performs the operation of detecting said optimum phase data train during a period during which the same burst data set is received and, if an optimum phase varies, said output data selector dynamically switches the optimum phase data to be supplied to said data synchronization unit in response to the control signal outputted from said phase determination unit.
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Abstract
A bit synchronization circuit composed of a multiphase data sampling unit for converting each received burst data sets to multiphase data trains, a phase determination unit for generating a control signal indicating an optimum phase data train, an output data selector for selectively passing optimum phase data train indicated by the control signal, and a data synchronization unit for converting the optimum phase data train to a data train in synchronization with a reference clock. The phase determination unit repeatedly detecting the optimum phase data train during the same burst data set is received. When optimum phase varies, the output data selector dynamically switches the optimum phase data train to be supplied to the data synchronization unit.
24 Citations
10 Claims
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1. A bit synchronization circuit for synchronizing, with an internal reference clock, burst data sets received in time series order, the circuit comprising:
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a multiphase data sampling unit for converting each of the received burst data sets to multiphase data trains having phases different from each other;
a phase determination unit for detecting, from among said multiphase data trains, an optimum phase data train having the highest phase margin over the reference clock and generating a control signal indicating the optimum phase data train;
an output data selector for selectively passing, of the multiphase data trains outputted from said data sampling portion, the optimum phase data train indicated by said control signal; and
a data synchronization unit for converting the data train passed through said output data selector to a data train in synchronization with said reference clock and outputting the resulting data train, wherein said phase determination unit repeatedly performs the operation of detecting said optimum phase data train during a period during which the same burst data set is received and, if an optimum phase varies, said output data selector dynamically switches the optimum phase data to be supplied to said data synchronization unit in response to the control signal outputted from said phase determination unit. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A central terminal for an optical transmission system for communicating with a plurality of remoter terminals, said central terminal having at least one subscriber line interface connected to an optical fiber for receiving burst data sets in time series order transmitted from the remoter terminals in time division multiplex, said optical fiber accommodating the plurality of remote terminals via a plurality of tributary optical fibers branched from the optical fiber with an optical coupler,
said subscriber line interface including an optical/electric signal converter for converting an optical signal received from said optical fiber to an electric signal, and a bit synchronization circuit connected to said optical/electric signal converter for synchronizing, with an internal reference clock, burst data sets supplied in an electric signal outputted from said optical/electric signal converter in time series order, said bit synchronization circuit comprising: -
a multiphase data sampling unit for converting each of the received burst data sets to multiphase data trains having phases different from each other;
a phase determination unit for detecting, from among said multiphase data trains, an optimum phase data train having the highest phase margin over the reference clock and generating a control signal indicating the optimum phase data train;
an output data selector for selectively passing, of the multiphase data trains outputted from said data sampling portion, the optimum phase data train indicated by said control signal; and
a data synchronization unit for converting the data train passed through said output data selector to a data train in synchronization with said reference clock and outputting the resulting data train, wherein said phase determination unit repeatedly performs the operation of detecting said optimum phase data train during a period during which the same burst data set is received and, if an optimum phase varies, said output data selector dynamically switches the optimum phase data to be supplied to said data synchronization unit in response to the control signal outputted from said phase determination unit. - View Dependent Claims (10)
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Specification