| US 7,542,672 B2 | ||
| Optical switching apparatus with optical reflection monitor and reflection monitoring system | ||
| Sunao Kakizaki, Kawasaki (Japan); Hideaki Tushima, Tokyo (Japan); Sigeki Kitajima, Kawasaki (Japan); and Yasuyuki Fukashiro, Yokohama (Japan) | ||
| Assigned to Hitachi, Ltd., Tokyo (Japan) | ||
| Filed on May 23, 2007, as Appl. No. 11/802,453. | ||
| Application 11/802453 is a division of application No. 10/058781, filed on Jan. 30, 2002. | ||
| Claims priority of application No. 2001-237856 (JP), filed on Aug. 06, 2001. | ||
| Prior Publication US 2007/0223918 A1, Sep. 27, 2007 | ||
| Int. Cl. H04B 10/08 (2006.01); H04B 17/00 (2006.01) | ||
| U.S. Cl. 398—12 [398/16; 398/19] | 4 Claims |
| 1. A method of detecting an optical reflection position in an optical switching unit by using a measuring system including
a reflected light meter having a light source for emitting a test light, a port selector for selectively supplying the test
light to one of the input ports of the optical switching unit, and a portable terminal connected to a control unit for controlling
the optical switching unit, the control unit being coupled to said reflected light meter and said port selector through a
bus, the method comprising the steps of:
giving a first switching command to said port selector from said control unit under control of said portable terminal so as
to input the test light emitted from said light source to specified one of input ports of said optical switching unit;
giving a second switching command to the optical switching unit from said control unit under control of said portal terminal
so that the optical switching unit changes an Internal path for conducting the test light supplied to said specified input
port to one of the output ports of the optical switching unit;
measuring, by said reflected light meter, the magnitude of a reflected light which is generated when a part of said test light
reflects at any abnormal position on the internal path and arrives at the reflected light meter through said port selector;
and
notifying said control unit of a reflected light measurement value from said reflected light meter,
wherein said control unit performs the steps of:
comparing the reflected light measurement value obtained from said reflected light meter with a threshold value;
storing into a memory, as status information of said internal path, an abnormal state flag when the reflected light measurement
value is not smaller than the threshold value and a normal state flag when the reflected light measurement value is smaller
than the threshold value; and
locating an abnormal position within the optical switching unit based on said status information stored in said memory after
said comparing step has been completed about a predetermined number of internal paths formed in the optical switching unit
by repeating said giving steps of said first switching unit by repeating said giving steps of said first switching command
and said second switching command,
wherein said control unit stores said status information in said memory in the form of a reflection alarm information table
in which said abnormal flag or said normal flag is stored in association with each of said internal paths, and
wherein said control unit detects a rearmost connection among said optical interconnections in the optical switching unit
as said abnormal position based on said reflection alarm information table and said interconnection control table.
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