CMI encoder circuit
AssigneeNEC Corporation Of America
InventorSteven S. Gorshe
Life of this patent
Estimating the term…
Abstract
A Coded Marked Inversion (CMI) encoding circuit having a completely synchronous and digital implementation for encoding a stream of digital data in non-return-to-zero (NRZ) format into the CMI format. The encoding circuit includes a clock for providing a clock signal having a certain period, an input circuit for obtaining two samples of the NRZ data during each clock period, and a state machine which, in response to the two samples of the NRZ data, produces CMI encoded data. In a more advanced implementation, the encoding circuit includes error encoding circuitry for detecting errors in the incoming samples of NRZ data. The encoding circuit then outputs data indicative of the rate at which errors are received.
Claims23
An apparatus for encoding non-return-to-zero (NRZ) data into Coded Marked Inversion (CMI) format comprising:
- a clock which generates a clock signal of a predetermined period;
- input means, coupled to said clock, for sampling said NRZ data during each period of the clock signal;
- and
- a state machine, coupled to said input means for receiving samples of said NRZ data, and encoding said samples of NRZ data into CMI format, said state machine having a set of legal states and zero illegal states, and comprising first means for producing in response to the sampling of said NRZ data a first value during a first predetermined number of the legal states;
- and second means for producing in response to the sampling of said NRZ data and said first value, a second value during a second predetermined number of the legal states, wherein said first and second values represent the sample of NRZ data in CMI format.
A method of encoding non-return-to-zero (NRZ) data into Coded Marked Inversion (CMI) format comprising the steps of:
- providing a clocking signal having a predetermined period;
- obtaining a first sample of said NRZ data during said predetermined period;
- producing a first value in accordance with said first sample;
- obtaining a second sample of said NRZ data during said predetermined period;
- producing a second value in accordance with said first value and said sample;
- and
- combining said first and second values to generate a CMI coded value, and outputting said CMI coded value.
An apparatus for encoding non-return-to-zero (NRZ) data into Coded Marked Inversion (CMI) format comprising:
- a clock for providing a clock signal having a predetermined period;
- and
- a state machine responsive to said clock signal for receiving at least one sample of said NRZ data, said state machine having zero illegal states and a predetermined number of legal states, each of said legal states outputting a first or second value in response to said at least one sample of NRZ data, said state machine being operative to transition between different ones of said predetermined number of legal states to produce a combination of said first and second values, said combination represents said at least one sample of NRZ data in CMI format.
Dependencies are inferred from the claim text.