# US 7,466,921 B2 · Drop-and-continue device

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- Number: US 7,466,921 B2
- Document ID: US7466921B2
- Status: Granted
- Kind: B2
- Application number: 11/183,887
- Filed: 2005-07-19
- Published: 2006-10-05
- Granted: 2008-12-16
- Earliest claimed: 2005-03-31
- Assignees: Fujitsu Limited
- Inventors: Hatsumi Haishima
- Web page: https://patentgrep.com/patent/US7466921B2

## CPC

- H04J 14/028: {WDM bus architectures}
- H04J 14/0201: {Add-and-drop multiplexing}
- H04J 14/0228: {Wavelength allocation for communications one-to-all, e.g. broadcasting wavelengths}
- H04J 14/0241: {Wavelength allocation for communications one-to-one, e.g. unicasting wavelengths}
- H04J 14/0206: {Express channels arrangements}
- H04J 14/0226: {Fixed carrier allocation, e.g. according to service}
- H04J 14/0227: {Operation, administration, maintenance or provisioning [OAMP] of WDM networks, e.g. media access, routing or wavelength allocation}
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)

## Abstract

Disclosed is a drop-and-continue device (84), provided between a signal converter (85) which supplies a signal to an end user and a wavelength-division multiplexing device (83) which comprises an optical demultiplexer (831) for separating an optical signal of a desired wavelength from an optical signal supplied from a head end station (82) and an optical multiplexer (832) for supplying an optical signal to a wavelength-division multiplexing device at a subsequent stage, comprising: an optical receiver (841) which converts the optical signal separated by the optical demultiplexer into an electrical signal; a transmitter (844) which transmits the electrical signal to the end user via the signal converter (85); an optical transmitter (845) which supplies an optical signal to the optical multiplexer (832); and a loopback processor (842) which loops the electrical signal output from the optical receiver back to the optical transmitter, thereby providing a drop-and-continue device that can easily add capabilities best suited for video, voice, and entertainment distribution and other added value features onto a WDM device.

## Claims

### Claim 1

A drop-and-continue device provided between a signal converter which supplies data and a signal to an end user and a wavelength-division multiplexing device which comprises an optical demultiplexer separating an optical signal of a desired wavelength from an optical signal supplied from a wavelength-division multiplexing device in a head end station and an optical multiplexer supplying an optical signal to a wavelength-division multiplexing device at a subsequent stage, the drop-and-continue device comprising:
an optical receiver which converts the optical signal separated by the optical demultiplexer into an electrical signal;
a transmitter which transmits the electrical signal to the end user via the signal converter in the form of either an electrical signal or an optical signal;
an optical transmitter which supplies an optical signal to the optical multiplexer; and
a loopback processor which loops the electrical signal output from the optical receiver back to the optical transmitter.

### Claim 2 (depends on 1)

The drop-and-continue device as claimed in claim 1, wherein the optical transmitter includes a wavelength conversion means, thereby supplying to the optical multiplexer an optical signal of a wavelength different from the wavelength of the optical signal received by the optical receiver.

### Claim 3 (depends on 1)

The drop-and-continue device as claimed in claim 1, further comprising a CPU interface which makes possible signal transmission and reception between the optical transmitter, the transmitter, and the wavelength-division multiplexing device, thereby making it possible to remotely control the drop-and-continue device from the wavelength-division multiplexing device in the head end station.