The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Sep. 21, 2004
Filed:
Aug. 25, 2000
Applicant:
Inventor:
Masayuki Nakano, Tokyo, JP;
Assignee:
NEC Corporation, Tokyo, JP;
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04B 1/000 ; H04B 1/006 ; H04B 1/700 ; H04Q 1/20 ; H04L 7/02 ;
U.S. Cl.
CPC ...
H04B 1/000 ; H04B 1/006 ; H04B 1/700 ; H04Q 1/20 ; H04L 7/02 ;
Abstract
A circuit for monitoring an optical signal level provided in an optical receiver includes a clock extraction circuit, a noise detection circuit, and an alarm circuit. The clock extraction circuit extracts a clock from an input signal. The noise detection circuit multiplies the clock, utilizes the multiplied clock to identify surge noises included in the input signal, and outputs noise pulses. The alarm circuit counts the noise pulses and outputs an alarm signal when the number of the pulses counted within a certain period reaches a preset value. The surge noise is a noise having a level which is relatively increased as the input signal level is lowered.