# US 10,374,703 B2 · Transmission device and signal monitoring method

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- Number: US 10,374,703 B2
- Document ID: US10374703B2
- Status: Granted
- Kind: B2
- Application number: 16/110,451
- Filed: 2018-08-23
- Published: 2019-03-14
- Granted: 2019-08-06
- Earliest claimed: 2017-09-14
- Assignees: Fujitsu Limited
- Applicants: Fujitsu Limited
- Inventors: Shoichiro Oda; Takeshi Hoshida; Hisao Nakashima; Yi Ge
- Web page: https://patentgrep.com/patent/US10374703B2

## CPC

- H04B 10/07953: {Monitoring or measuring OSNR, BER or Q}
- H04B 10/0775: {Performance monitoring and measurement of transmission parameters}
- H04J 14/02126: {Multicast switch arrangements}
- H04L 1/20: using signal quality detector
- H04L 1/205: {jitter monitoring}
- H04B: TRANSMISSION
- 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)
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)

## Abstract

A transmission device includes: a receiving unit that receives an optical signal; an acquiring unit that acquires spectrum information from the optical signal, the spectrum information relating to a spectrum of the optical signal; and a narrowing calculating unit that calculates an index value for narrowing of a band of the optical signal by calculating a sampling timing error in accordance with the spectrum information, the sampling timing error being an error when a clock signal is extracted from the optical signal.

## Claims

### Claim 1

A transmission device comprising:
a receiving unit that receives an optical signal;
an acquiring unit that acquires spectrum information from the optical signal, the spectrum information relating to a spectrum of the optical signal; and
a narrowing calculating unit that calculates an index value for narrowing of a band of the optical signal by calculating a sampling timing error in accordance with the spectrum information, the sampling timing error being an error when a clock signal is extracted from the optical signal.

### Claim 2 (depends on 1)

The transmission device according to claim 1, wherein
the narrowing calculating unit calculates the index value for the narrowing for each type of an error correction code included in the optical signal, and
the transmission device further comprises
a selecting unit that selects a type of the error correction code in accordance with the index value for the narrowing.

### Claim 3 (depends on 2)

The transmission device according to claim 2, further comprising
a signal quality calculating unit that calculates signal quality of the optical signal for each type of the error correction code,
wherein the selecting unit selects a type of the error correction code in accordance with the signal quality and the index value for the narrowing.

### Claim 4 (depends on 1)

The transmission device according to claim 1, wherein
the narrowing calculating unit calculates a change in the index value for the narrowing with respect to a center frequency of the optical signal, and
the transmission device further comprises
a determining unit that determines the center frequency of the optical signal in accordance with the change in the index value for the narrowing.

### Claim 5 (depends on 4)

The transmission device according to claim 4, further comprising
a signal quality calculating unit that calculates a change in signal quality of the optical signal with respect to the center frequency of the optical signal,
wherein the determining unit determines the center frequency of the optical signal in accordance with the change in the signal quality and the change in the index value for the narrowing.

### Claim 6 (depends on 1)

The transmission device according to claim 1, wherein
the receiving unit receives the optical signal subjected to pre-equalization, and
the transmission device further comprises
a control unit that controls pre-equalization of the optical signal in a device in accordance with the index value for the narrowing, the device being a transmission source of the optical signal.

### Claim 7 (depends on 6)

The transmission device according to claim 6, further comprising
a signal quality calculating unit that calculates signal quality of the optical signal,
wherein the control unit controls the pre-equalization of the optical signal in accordance with the signal quality and the index value for the narrowing.

### Claim 8

A signal monitoring method comprising:
receiving an optical signal;
acquiring spectrum information from the optical signal, the spectrum information relating to a spectrum of the optical signal; and
calculating an index value for narrowing of a band of the optical signal by calculating a sampling timing error in accordance with the spectrum information, the sampling timing error being an error when a clock signal is extracted from the optical signal.

### Claim 9 (depends on 8)

The signal monitoring method according to claim 8, wherein
the index value for the narrowing is calculated for each type of an error correction code included in the optical signal, and
the signal monitoring method further comprises
selecting a type of the error correction code in accordance with the index value for the narrowing.

### Claim 10 (depends on 9)

The signal monitoring method according to claim 9, further comprising
calculating signal quality of the optical signal for each type of the error correction code,
wherein a type of the error correction code is selected in accordance with the signal quality and the index value for the narrowing.

### Claim 11 (depends on 8)

The signal monitoring method according to claim 8, wherein
a change in the index value for the narrowing with respect to a center frequency of the optical signal is calculated, and
the signal monitoring method further comprises
determining the center frequency of the optical signal in accordance with the change in the index value for the narrowing.

### Claim 12 (depends on 11)

The signal monitoring method according to claim 11, further comprising
calculating a change in signal quality of the optical signal with respect to the center frequency of the optical signal,
wherein the center frequency of the optical signal is determined in accordance with the change in the signal quality and the change in the index value for the narrowing.

### Claim 13 (depends on 8)

The signal monitoring method according to claim 8, wherein
the optical signal subjected to pre-equalization is received, and
the signal monitoring method further comprises
controlling pre-equalization of the optical signal in a device in accordance with the index value for the narrowing, the device being a transmission source of the optical signal.

### Claim 14 (depends on 13)

The signal monitoring method according to claim 13, further comprising
calculating signal quality of the optical signal,
wherein the pre-equalization of the optical signal is controlled in accordance with the signal quality and the index value for the narrowing.