JP3039811B2 - Repeater monitoring method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitoring system for a repeater of a relay transmission system. In particular, the present invention is used for monitoring a repeater in an optical repeater system using a non-regenerative repeater.

[0002]

2. Description of the Related Art As a conventional repeater monitoring method, there is a repeater monitoring method in a relay transmission system using a regenerative repeater circuit. FIG. 11 shows the configuration of a regenerative repeater in this relay transmission system.

[0003] This repeater converts an input main signal into an amplifying section.
The signal is amplified at 11, output, detected by the four-phase detector 12, and discriminated and reproduced by the discrimination reproduction circuit 13. The signal subjected to the identification and reproduction is subjected to code conversion by the code conversion circuit 14, and then subjected to phase modulation by the four-phase phase modulator 15 and output to the next-stage repeater.

In this case, in order to transmit a supervisory control signal transmitted from a terminal station, a phase shift keying (PSK) is performed by a main signal using a four-phase modulator 15 and a transmission local oscillator 18 having a built-in voltage-controlled oscillator. A configuration is known in which the carrier wave is further frequency-shift-keyed (FSK) by a monitor control signal 22 output from a monitor control circuit 21.

Literature Kubo, Kanehori, Kuramoto 20G-400 Monitoring and control system for M system

[0006]

[Problems that the Invention is to Solve In this case, since the transmitting supervisory signal from the terminal station to each repeater is each repeater regenerative relay method, as shown in FIG. 11, in each repeater Carrier extraction unit 16 having the function of demodulating the supervisory control signal once
Also, the transmission local oscillator 18 having a function of superimposing the monitoring signal again on the signal reproduced and relayed thereafter is required, and there has been a problem that the configuration becomes complicated.

Further, in order to transmit monitor information for relaying various circuit states in the repeater shown in FIG. 11 to the terminal, the monitor control signal 20 received by the repeater and the state of various circuits are shown. Monitor and control circuit 21 that multiplexes the monitoring signal
Therefore, there is a problem that the configuration of the monitoring control circuit 21 becomes complicated.

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the conventional regenerative repeater repeater, and to simplify transmission of a supervisory control signal from a terminal to a repeater and transmission of a supervisory signal from the repeater to a terminal. It is an object of the present invention to provide a repeater monitoring method that can be performed with a simple configuration.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a relay transmission system including a pair of terminal stations connected by a transmission line and a plurality of non-regenerative repeaters disposed between the two terminal stations. In a monitoring method of a repeater, the repeater includes a means for generating a monitor signal to be transmitted to at least one of the terminal stations;
The signal transmitted through the transmission line by the monitor signal generated by this means is used to convert the intensity of the pump light source of the rare earth doped amplifier.
Means for performing gain modulation by modulation, wherein at least one of the terminal stations includes means for demodulating and extracting the monitor signal transmitted from the repeater from a received signal.

[0010] The present invention also relates to a repeater monitoring method for a relay transmission system including a pair of terminal stations connected by a transmission line and a plurality of non-regenerative repeaters disposed between the two terminal stations. In the system, one terminal station has means for modulating a signal carrier according to a main signal, and the modulated signal carrier is modulated according to a supervisory control signal transmitted to the repeater and coupled to a transmission path. Means for demodulating and extracting the monitoring control signal transmitted from the terminal station, and generating a monitoring signal to be sent to the one terminal station or the other terminal station. Means and a rare earth-doped signal transmitted through the transmission line by a monitor signal generated by the means.
Means for performing gain modulation by intensity modulation of a pump light source of an amplifier, wherein the one terminal or the other terminal includes means for demodulating and extracting the monitor signal transmitted from the repeater from a received signal. It is characterized by having.

Further, the transmission line has both an uplink line and a downlink line, and there are four modulation systems of a modulation system using a monitor control signal at a terminal station of the transmission line of the both lines and a modulation system using a monitor signal at a repeater. At least one of them can use a modulation scheme different from the others.

Further, the transmission line has both an uplink line and a downlink line, and has four modulation systems of a modulation system using a monitoring control signal at a terminal station of the transmission line of the both lines and a modulation system using a monitoring signal at a repeater. At least one of them can be a signal of a frequency band different from the other as a modulation input.

Further, the present invention relates to a relay transmission monitoring system including a pair of terminal stations connected by a transmission line and a plurality of non-regenerative repeaters disposed between the two terminal stations. In the system, the transmitting device of one of the terminal stations includes a means for generating a supervisory control signal superimposed on the main signal, an oscillator for generating a signal carrier for carrying the supervisory control signal, and an oscillator signal carrier for the oscillator. Modulating means for modulating by a supervisory control signal, and modulation transmitting means for intensity-modulating the optical signal of the main signal by the signal carrier modulated by the supervisory control signal and coupling the signal to a transmission path, wherein the repeater includes: An optical coupler for extracting a part of the optical signal of the optical transmission line, a means for demodulating a signal carrier modulated with the supervisory control signal from the extracted optical signal to demodulate the supervisory control signal, Monitoring results Means for generating a monitor signal consisting of a report signal, means for generating and modulating a signal carrier having a frequency different from the signal carrier modulated by the monitor control signal by the monitor signal, and a rare earth element formed by the modulated signal carrier. Modulating means for intensity-modulating the pump light source of the doped amplifier to gain- modulate the optical signal on the transmission line, and the receiving device of the one terminal station or the other terminal station receives, from the received optical signal, A demodulator for demodulating the transmitted monitoring signal is provided.

[0014]

According to the present invention, the repeater performs non-regenerative relay transmission. In the present invention, the supervisory control signal from the transmitting terminal to the repeater is transmitted by being superimposed on the main signal by the supervisory control signal carrier. For this reason, the monitor control signal is relay-transmitted along with the relay transmission by the non-regenerative relay function for amplifying the main signal provided in each relay. Also, the monitoring signal from each repeater is a monitoring signal carrier (hereinafter, both the monitoring control signal carrier and the monitoring signal carrier are called subcarriers).
Is superimposed on the main signal and relayed to the receiving device at the receiving terminal station.

At this time, by changing the frequency of the monitor signal subcarrier from the repeater, the monitor control signal transmitted from the terminal station and each repeater and each monitor signal can be frequency division multiplexed and transmitted. Also, multiplex transmission of both signals is possible by changing the modulation method of the monitoring control signal at the terminal station and the modulation method of the monitoring signal at the repeater.

[0016] Thus, since there is no additional function for relaying the supervisory control signal and the supervisory signal in each repeater, the configuration of the repeater can be simplified.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIGS. 1 and 2 show the configuration of a first embodiment of the present invention. In this embodiment, a main signal is transmitted on an optical transmission line 37 by an optical signal in which an FSK modulation in an optical region is performed. This is an example in which the present invention is applied to a system.

A pair of terminal stations are connected by upstream and downstream optical transmission lines 37a, 37b, 48a, 48b, respectively, and a plurality of repeaters 56a, 56b are arranged between the terminal stations. One terminal station has an upstream transmission device 55
a and a receiving device 57b for the downlink. The terminal station opposite to the device a includes a receiving device 57a for the uplink and a transmitting device 55b for the downlink.

The configuration of this embodiment will be described with reference to the configuration of the uplink in FIG.

The transmitting device 55a of one terminal station of this uplink line
The laser diode (L
D) An LD driving circuit 31a for driving 32a, and a laser diode 32a for converting a main signal into an optical signal. An optical signal output from the laser diode 32a is input as a modulated input of an intensity modulator 33a. The modulation output of the modulator 33a is coupled to the optical transmission path 37a. The monitoring control signal transmitted from the transmitting device 55a to each repeater 56a is output from the monitoring control signal generator 36a to the modulation input of the multiplier 35a,
The subcarrier of frequency f1 output from 34a is output to the modulated input of multiplier 35a. The f1 subcarrier signal intensity-modulated by the multiplier 35a is input as a modulation input of an intensity modulator 33a that performs ASK modulation on the output optical signal of the laser diode 32a.

The uplink repeater 56a includes an erbium fiber amplifier 38a and amplifies and repeats a transmission signal.
An optical coupler 40a for extracting a part of the optical signal is provided at a stage subsequent to the erbium fiber amplifier 38a. The output of the optical coupler 40a is guided to a photodetector 41a for performing optical detection. Band-pass filter 42 having the center band at the frequency of the subcarrier f1 on which
a and is filtered. This bandpass filter 42a
The subcarrier signal of f1 filtered by the
The monitoring control signal is demodulated by being input to a and is input to the monitoring control circuit 44a in the repeater. Information obtained by monitoring various circuits in the repeater by the monitor control circuit 44a is output as a monitor signal. Modulation input. Modulated by monitoring signal
The subcarrier f2 is input to the control input of the pump light source 47a of the erbium fiber amplifier 38a of the repeater 56a, and modulates the intensity of the pump light source 47a. The output of the pump light source 47a is coupled to an erbium fiber amplifier 38a by a multiplexer 39a, and amplifies and modulates the optical signal on the optical transmission line. The figure
As shown in FIG. 2 , the output of the supervisory control circuit 44a can be used as the modulation input of the multiplier 45b on the downlink.

Uplink receiver 57 of the opposite receiving terminal station
At a, a main signal receiving circuit 50a is coupled to an optical transmission line 48a. The receiving device 57a is provided with an optical coupler 49a for extracting a part of the received optical signal. The optical signal extracted by the optical coupler 49a is detected by a photodetector 51a, and a bandpass filter 52 for filtering a center frequency band of a subcarrier frequency f2 on which a monitoring signal from a repeater is superimposed.
a is provided, and the repeater 56a extracts the subcarrier f2 of the monitor signal superimposed on the transmission signal. The extracted subcarrier of f2 is envelope-detected by the envelope detector 53a, and a monitoring signal transmitted by the subcarrier of f2 is extracted to monitor the repeater.
Input to 54a.

The downlink configuration also has the same structure faces the uplink as shown in FIG. 2 (b).

Next, the operation of the first embodiment will be described with reference to the operation of the uplink.

When the supervisory control signal generator 36a intends to perform supervisory control, for example, "0", "1" for identifying a repeater
And a supervisory control signal composed of an identification code composed of the following symbols and a supervisory control command code. The oscillator 34a oscillates a subcarrier composed of a sine wave having a frequency f1. The subcarrier f1 is input to the multiplied input (modulated input) of the multiplier 35a, the monitoring control signal is input to the multiplication input (modulation input), and the subcarrier f1 is intensity-modulated by the monitoring control signal. The main signal is obtained by changing the amount of current injected into the laser diode 32a in accordance with the transmission code, so that the light F
It is modulated and output as an SK modulation signal. Intensity modulator 33
a represents the optical signal FSK-modulated by the main signal as A
SK (Amplitude shift keying) modulation is performed and output, and coupled to the optical transmission line 37a. As a result, the monitor control signal is superimposed on the main signal and transmitted as a subcarrier ASK signal or a subcarrier AM signal of the frequency f1.

In the repeater 56a, after being amplified by the erbium fiber amplifier 38a having a gain to compensate for the fiber loss, a part of the optical signal is extracted by the optical coupler 40a.
The light is directly detected by the light receiver 41a. This detection output is filtered by a band-pass filter 42a of a pass band including the frequency f1, and then a monitoring control signal superimposed on the transmission signal and transmitted by the transmitting device 55a of the transmitting terminal is extracted by the envelope detector 43a. . The extracted supervisory control signal is input to the supervisory control circuit 44a, which recognizes that it is the supervisory control for its own repeater based on the signal content of the supervisory control signal, and responds to the command contained in the supervisory control signal by its own Performs a monitoring operation instructed such as monitoring a circuit in the chamber.

The monitoring signal transmitted from the repeater 56a to the receiving device 57a of the other receiving terminal is transmitted to the monitoring control circuit 44a.
Are output as digital signals having values of "0" and "1", and input to the multiplier 45a. Since the subcarrier of f2, which is a frequency different from the subcarrier of f1 on which the monitor control signal is superimposed, is input from the oscillator 46a to the modulated input of the multiplier 45a, the subcarrier of f2 is the monitor signal. The intensity of the light is modulated by the intensity control signal to become the intensity control input of the pump light source 47a. Since the gain of the erbium fiber amplifier 38a is modulated by the intensity modulation of the output of the pump light source 47a, the monitor signal from the repeater 56a is superimposed on the main signal as a subcarrier ASK signal or a subcarrier AM signal.

FIG. 2 shows a frequency spectrum when both the upstream and downstream transmission signals are directly detected. As shown in FIG. 3 , since the subcarrier frequency of the monitoring control signal superimposed by the transmitting device 55 of the transmitting terminal and the monitoring signal superimposed by the repeater 56 are different, a bandpass filter is used in each repeater. By using this, it becomes possible to receive a monitoring control signal addressed to each repeater.

The main signal of the optical signal received by the receiving device 57a of the receiving terminal is received and demodulated by the main signal receiving circuit 50a.
A part of the received optical signal is taken out by the optical coupler 49a, detected directly by the light receiver 51a, and
After being filtered by the band-pass filter 52a in the band of f2, envelope detection is performed by the envelope detector 53a, and the monitoring signal transmitted from the repeater is demodulated and input to the monitoring signal receiver 54a.

In this way, transmission of the supervisory control signal from the terminal station to the repeater and transmission of the supervisory signal from inside the repeater to the terminal station can be performed simultaneously.

The downlink has the same structure, and the downlink transmission device 55b transmits a supervisory control signal to each repeater by using a subcarrier whose center frequency is the frequency f3.
The repeater also superimposes the supervisory signal on the downlink optical transmission path 48b and transmits the supervisory signal to the receiving device 57b using the subcarrier for superimposing the supervisory signal having the center frequency of the frequency f4. As a result, both the uplink and the downlink can transmit the monitoring control signal from the transmitting device of the terminal station to the repeater and the monitoring signal from the relay device to the receiving device of the terminal station.

As shown in FIG. 2 , the monitoring control circuit 44a
Is coupled to the multiplier 45b on the downlink side, the supervisory signal from this repeater can be transmitted on the downlink. In this case, one terminal station can monitor and control the repeater by transmitting the monitor control signal on the uplink and receiving the monitor signal from the repeater on the downlink.

Here, the direct detection circuit in the receiving device 57 or the repeater 56 can be replaced with a circuit for performing envelope detection after heterodyne detection or a circuit for performing homodyne detection. The heterodyne detection circuit example in FIG. 4 (a), shows a circuit example using a homodyne detection circuit in Figure 5 (b). The local oscillator 60 is a heterodyne detection circuit, an optical coupler 61 for coupling the received optical signal to the local oscillation wave, intermediate frequency band envelope detector 62 is added to the circuit of FIG. 1 and 2.
In homodyne detection circuit includes an optical coupler 61, is added to the local oscillator circuit (phase control circuit) 63 Togazu 1 and 2 as a control input of the local oscillator 60.

In the first embodiment, the repeaters are supervised by sequentially transmitting a supervisory control signal using subcarriers of frequency f1 for each repeater, and instructing the supervision, and each repeater transmits the supervisory signal to the frequency f2. Is transmitted to the opposite terminal station on the subcarrier. This monitoring is performed in a time-sharing manner. On the other hand, monitoring can be performed by frequency division as a configuration in which the oscillation frequency of the subcarrier for transmitting the monitoring signal is monitored as a different frequency for each repeater.

FIG. 6 shows the configuration of the receiving apparatus 57 in the case where the monitoring signal transmission subcarriers have all different configurations. In the receiving device 57 of the receiving terminal station, the band-pass filters 52-1 and 52-2 corresponding to the subcarrier frequencies (f2-1, f2-2... F2-n) of the supervisory signal received from each repeater are received. ,... 52-n are provided, and after being filtered by the n number of band-pass filters 52, the envelope detectors 53-1 and 53-2. At the same time. FIG. 7 shows an example of a frequency spectrum when such a transmission signal is directly detected.

In the first embodiment, the subcarrier AS
Although the K signal has been described, a supervisory control signal and a supervisory signal can be transmitted in the same manner by using a subcarrier FSK, a subcarrier PSK scheme, or a polarization modulation scheme modulator / demodulator circuit as the modem circuit.

Next, as a second embodiment of the present invention, FIG. 8 shows an example in which a subcarrier phase modulation signal is used as a modulation signal of a pump light source in the repeater of the first embodiment. In the second embodiment, a subcarrier wave of frequency f2 is phase-modulated by a multiplier 45 by a monitor signal such as monitor information from a repeater 56, and a subcarrier PSK is
This is a configuration for transmitting a monitoring signal by a signal. Here, the supervisory control circuit 44 in the repeater 56 uses a binary signal having a different sign and the same magnitude as the supervisory signal, for example, “1” and “−”.
1 "signal. As a result, the phase modulated subcarriers whose phases are opposite to each other are output from the multiplier 45 in correspondence with the monitoring signals “1” and “−1” with respect to the phase of the subcarrier having the frequency f2. As a result, the pump light source 47 is phase-modulated by the subcarrier on which the monitoring signal is superimposed.
The monitoring signal is transmitted by the SK signal.

In the second embodiment, a detector 73 comprising a delay detector or a synchronous detector in place of the envelope detector used in the demodulator of the first embodiment is provided in the receiving device 57 of the receiving terminal. The demodulation of the monitoring signal can be performed by using.

[0040] The configuration of the third embodiment of the present invention shown in FIG. This configuration shows an example in which the present invention is applied to a system in which a main signal is transmitted by an optical signal subjected to PSK modulation. In the third embodiment, the repeater 56 is configured to transmit the monitoring signal by phase modulation instead of the transmission of the monitoring signal by the subcarrier ASK modulation signal shown in the first embodiment. That is, the f2 subcarrier modulated by the monitor signal from the monitor control circuit 44 is input to the modulation input terminal of the phase modulator 71 provided at the subsequent stage of the erbium fiber amplifier 38. As a result, the phase modulation of the transmission signal is performed by the f2 subcarrier modulated by the monitor signal, and this is transmitted to the receiving device 57 of the receiving terminal station. In the receiving device 57, after performing heterodyne detection, as a demodulation circuit, a synchronous detection circuit 72 detects a subcarrier, extracts the subcarrier, filters the bandpass filter 52, and then extracts a monitoring signal from the repeater 56 by an envelope detector 53. . FIG. 10 shows an example of the frequency spectrum of the output demodulated by the synchronous detection circuit 72. As shown in FIG. 10 , since the band of the monitor signal from the repeater 56 and the band of the main signal are different, both components can be separated by the band-pass filter 52.

It should be noted that multiplex transmission of both signals is also possible by changing the modulation method by the monitoring control signal in the transmitting device and the modulation method by the monitoring signal in the repeater.

[0042]

As described above, according to the present invention, the monitoring control signal transmitted from the terminal station is received by detecting and demodulating the received signal or a part of the amplified received signal in the repeater. In addition, since the monitoring signal from the repeater is transmitted by the gain modulation of the amplifier used for amplifying the main signal by the subcarrier wave or the phase modulation of the main signal, a non-regenerative repeater repeater such as an optical fiber amplifier can be used. Can be monitored. In addition, since a special function to be added to the repeater is not required for the monitoring control, a simple monitoring control method is provided, and the reliability is improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an uplink system configuration according to a first embodiment of the present invention.

FIG. 2 is a system configuration diagram of a downlink according to the first embodiment of the present invention.

FIG. 3 is an example of a frequency spectrum of an output of a main signal in the first embodiment.

FIG. 4 is a configuration diagram of a demodulation circuit when the first embodiment employs a heterodyne detection method.

FIG. 5 is a configuration diagram of a demodulation circuit when the first embodiment is changed to a homodyne system.

FIG. 6 is an example of a demodulation circuit of a receiving device when the subcarrier frequencies of the repeaters are different.

FIG. 7 is an example of an output frequency spectrum of a receiving device.

FIG. 8 is a system configuration diagram of a second embodiment of the present invention.

FIG. 9 is a system configuration diagram of a third embodiment of the present invention.

FIG. 10 shows an example of an output frequency spectrum in the third embodiment.

FIG. 11 is a diagram showing a configuration of a conventional repeater.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H04L 27/32 (72) Inventor Shigeru Saito 1-6-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (72) Invention Yasushi Hara 5-7-1, Shiba, Minato-ku, Tokyo Within NEC Corporation (72) Inventor Masuo Suzuyama 1015 Ueodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture Inside Fujitsu Limited (56) References JP-A-2-2 119328 (JP, A) JP-A-2-252330 (JP, A) JP-A-62-247639 (JP, A) JP-A-2-186846 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04B 17/02 H04B 10/16 H04B 10/17

Claims (5)

(57) [Claims] 1. A relay monitoring system in a relay transmission system including a pair of terminal stations connected by a transmission line and a plurality of non-regenerative repeaters disposed between the two terminal stations, the repeater strength of at least means for generating a monitoring signal to be sent one to the signals transmitted through the transmission path by monitoring signals generated by the means of the rare earth doped amplifier pump source of the end station
Means for performing gain modulation by modulation, and at least one of the terminal stations includes means for demodulating and extracting the monitor signal transmitted from the repeater from a received signal. Monitoring system. 2. A repeater monitoring method in a relay transmission system including a pair of terminal stations connected by a transmission line and a plurality of non-regenerative repeaters disposed between the two terminal stations. The end station has means for modulating a signal carrier according to a main signal, and means for modulating the modulated signal carrier according to a monitoring control signal transmitted to the repeater and coupling the modulated signal carrier to a transmission path. The repeater includes: means for demodulating and extracting the monitoring control signal transmitted from the terminal station; means for generating a monitoring signal to be sent to the one terminal station or the other terminal station; The signal transmitted on the transmission line by the monitor signal generated by the means converts the intensity of the pump light source of the rare earth doped amplifier to
Means for performing gain modulation by modulation, wherein said one terminal station or the other terminal station includes means for demodulating and extracting the monitor signal transmitted from the repeater from a received signal. Monitoring method of the repeater. 3. A transmission line having both an uplink line and a downlink line, and four modulation systems including a modulation system using a monitor control signal at a terminal station of the transmission line of the both lines and a modulation system using a monitor signal at a repeater. 3. The monitoring method of a repeater according to claim 1, wherein at least one of the two uses a modulation method different from the other. 4. A transmission line having both an uplink line and a downlink line, and four modulation systems of a modulation system by a monitor control signal at a terminal station of the transmission line of both lines and a modulation system by a monitor signal at a repeater. claim 1 or claim 2 repeater monitoring method according at least one of the the modulated input signals of different frequency bands with other of. 5. A repeater monitoring method in a relay transmission system including a pair of terminal stations connected by a transmission line and a plurality of non-regenerative repeaters arranged between the two terminal stations. The transmitting device of the terminal station includes means for generating a monitoring control signal superimposed on the main signal, an oscillator for generating a signal carrier for carrying the monitoring control signal, and an oscillation signal carrier for the oscillator which is generated by the monitoring control signal. Modulating means for modulating, and modulation transmitting means for intensity-modulating the optical signal of the main signal with the signal carrier modulated by the monitoring control signal and coupling the modulated signal to a transmission path; an optical coupler for taking out a part of the optical signal, means for demodulating the monitoring control signal to demodulation the modulated signal carrier with the monitor control signal from the extracted optical signals, the monitoring result in the own repeater Consisting of information Means for generating a monitor signal; means for generating and modulating a signal carrier having a frequency different from the signal carrier modulated by the monitor control signal by the monitor signal; and means for controlling the rare-earth doped amplifier by the modulated signal carrier. Modulation means for intensity-modulating the pump light source to gain- modulate the optical signal on the transmission path, wherein the receiving device of the one terminal station or the other terminal station transmits the received optical signal from the repeater from the received optical signal. A monitoring method of a repeater including a demodulation means for demodulating a monitoring signal.