Error counting circuit
AssigneeFujitsu Limited
InventorsKatsumi Fukumitsu, Tadayuki Takada
Life of this patent
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Abstract
An error counting circuit is adapted to count a number of code errors of a main signal in an external apparatus which is coupled to an optical transmission path. The error counting circuit includes an error counter which counts error pulses received from the external apparatus and indicative of the number of code errors of the main signal in response to clock pulses having a predetermined period and outputting a counted value for each the predetermined period, and a mechanism for stopping a counting operation of the error counter when a power failure of the external apparatus occurs, so that an erroneous counting operation of the error counter is prevented.
Claims7
An error counting circuit for counting a number of code errors in a main signal in an external apparatus which is coupled to an optical transmission path, said error counting circuit comprising:
- an error counter for counting error pulses received from the external apparatus and indicative of the number of code errors in the main signal in response to clock pulses having a predetermined period and outputting a counted value for each said predetermined period;
- and
- means for stopping a counting operation of said error counter when a power failure of the external apparatus occurs,
- wherein said stopping means includes a gate through which said error counter receives the error pulses, said gate making a differential input with respect to said error counter based on the error pulses from the external apparatus and inverted error pulses from the external apparatus having a phase which is inverted relative to a phase of the error pulses.
An error counting circuit for counting a number of code errors in a main signal in an external apparatus which is coupled to an optical transmission path, said error counting circuit comprising:
- an error counter for counting error pulses received from the external apparatus and indicative of the number of code errors in the main signal in response to clock pulses having a predetermined period and outputting a counted value for each said predetermined period;
- and
- means for stopping a counting operation of said error counter when a power failure of the external apparatus occurs,
- wherein said stopping means includes a circuit through which said error counter receives the error pulses, said circuit receiving from the external apparatus the error pulses and sampling pulses for detecting the error pulses in the external apparatus and supplying to said error counter only the error pulses synchronized to the sampling pulses;
- wherein said stopping means includes a pulse width detector detecting whether or not a pulse width of the error pulses is normal and disabling the counting operation of said error counter when an abnormal pulse width of the error pulses is detected.
An error counting circuit for counting a number of code errors in a main signal in an external apparatus which is coupled to an optical transmission path, said error counting circuit comprising:
- an error counter for counting error pulses received from the external apparatus and indicative of the number of code errors in the main signal in response to clock pulses having a predetermined period and outputting a counted value for each said predetermined period;
- means for stopping a counting operation of said error counter when a power failure of the external apparatus occurs;
- and
- wherein said stopping means includes a pulse width detector for detecting whether or not a pulse width of the error pulses is normal and disabling the counting operation of said error counter when an abnormal pulse width of the error pulses is detected.
Dependencies are inferred from the claim text.