| US 7,526,200 B2 | ||
| Wavelength-division multiplexing optical transmitter | ||
| Hiroyuki Nakano, Yokohama (Japan); and Yasuyuki Fukashiro, Yokohama (Japan) | ||
| Assigned to Hitachi Communication Technologies, Ltd., Tokyo (Japan) | ||
| Filed on Aug. 29, 2005, as Appl. No. 11/212,576. | ||
| Claims priority of application No. 2004-251525 (JP), filed on Aug. 31, 2004. | ||
| Prior Publication US 2006/0045520 A1, Mar. 02, 2006 | ||
| Int. Cl. H04B 10/08 (2006.01) | ||
| U.S. Cl. 398—34 [398/10; 398/14; 398/15; 398/22; 398/23; 398/33; 398/36] | 7 Claims |
| 1. An optical transmission apparatus comprising:
a memory for storing a time when each optical transmitter starts to transmit an optical signal;
optical transmitters for transmitting optical signals;
first monitor units for monitoring optical signals from the optical transmitters;
a multiplexer for multiplexing the optical signals from the optical transmitter into a multiplexed signal;
a second monitor unit for monitoring each optical signal which is multiplexed in the multiplexed signal from the multiplexer;
and
a processing unit for detecting an overlap in wavelength of transmitted optical signals according to a result of monitoring
of the first and the second monitor units;
wherein the processing unit determines which one of the optical transmitters whose time is stored in the memory has a time
which is nearest to the time when the overlap was detected as an indication of a failure of the one of the optical transmitter.
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