JPH09280944A - Automatically reception level measuring system for light branching system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automatically reception level measuring system for a light branching system which is completely free from interruption between a slave station and a master station and dispenses with direct operation of equipment by a maintenance person. SOLUTION: At a master station 11, a signal S2 for measuring reception levels overlapped on a main signal is converted to an electric signal by an O/E and a main signal 81 is extracted through an LPF 13 while the signal S2 for measuring reception levels is extracted through a BPF16. A peak detecting section 17 detects a peak voltage of the signal S2. A CPU 19 calculates a reception level from the peak voltage based on a peak voltage is reception level characteristic previously applied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automatic light receiving level measuring system for an optical branching system, and more particularly to a light receiving level automatic measuring system for a star type optical branching system.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram of a star type optical branching system. In the star type optical branching system, one master station 101 and a plurality of (for example, three) slave stations 102 to 104 are used as the optical branching device 1.
The optical fiber transmission lines 106 to 109 are connected to each other via 05. Due to the configuration of such a system, the slave station 10
The burst signals transmitted from 2 to 104 are combined by the optical branching device 105 via the optical fiber transmission lines 107 to 109, and further transmitted via the optical fiber transmission line 106 to the master station 10.
Reach 1

Therefore, when two or more transmissions are input to the optical branching device 105 at the same time, a burst signal collision occurs. Therefore, in general, the TDMA method (time division multiple access method) is used for collision. To prevent.

By the way, when a slave station is newly installed, various pre-operation tests are performed, but it is necessary for the master station side to measure the received light level from the slave station. Conventionally, in the measurement of the received light level, the maintenance person goes to the slave station to be measured and directly operates the switch or the like to constantly output the transmitted light. On the other hand, on the side of the master station, the maintenance person also operates the optical fiber 106 and the master station 101. The O / E module (optical / electrical conversion module) (not shown) was disconnected, and a measuring device such as an optical power meter was connected to the optical fiber 106 to measure the received light level from the slave station to be tested.

Further, as a prior art relating to the measurement of optical power, (1) Japanese Unexamined Patent Publication No. 2-221838 discloses a technique for simultaneously measuring the optical power of light of different wavelengths,
(2) Japanese Patent Application Laid-Open No. 62-222129 discloses a technique for collectively measuring the optical power from a large number of optical fibers by using one optical sensor, and (3) Japanese Patent Application No. 62-3265.
Japanese Unexamined Patent Publication No. 2 (1994) discloses a technique in which the light wavelength-multiplexed lights are separated into lights of a single wavelength and the optical power is measured for each single wavelength.

[0006]

However, the conventional measuring system has a drawback in that all communication is interrupted while measuring the received light level.

For this reason, conventionally, only one slave station is not expanded later, but all slave stations are subjected to the pre-operation test at the same time.

There is also a drawback that the maintenance person must directly operate the equipment. This means that for child stations, maintenance personnel must be sent directly to the site.

In addition, there is a possibility that the operation of the device may be an erroneous operation. Especially for the master station, attaching or detaching the optical fiber may cause mechanical troubles.

On the other hand, the prior arts (1) to (3) do not disclose any technique capable of measuring the light reception level of one slave station without interrupting communication.

Therefore, an object of the present invention is to provide an automatic light receiving level measuring system for an optical branching system without interrupting communication between the slave station and the master station and requiring no maintenance personnel to directly operate the equipment. is there.

[0012]

In order to solve the above-mentioned problems, according to the present invention, one master station and a plurality of slave stations are connected in a star shape, and the master station receives light from each slave station. In the automatic light reception level measuring system of the optical branching system for measuring the signal, the master station separates the reception signal from each slave station into a main signal and a reception level measuring signal, and the separation means. And a signal converting means for converting the received signal for measuring a received level into an analog level signal.

Further, it is characterized by further comprising remote operation means for causing the master station to perform measurement of the light reception level by remote operation.

[0014]

According to the present invention, a master station separates a received main signal and a received level measuring signal into respective signals, converts the received level measuring signal into an analog level signal, and then converts the analog level signal. The light receiving level is calculated from the level.

Further, the master station measures the light reception level from a predetermined slave station under the control of the remote control means.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. The same components as those in the conventional example are designated by the same reference numerals, and the description thereof will be omitted.

The connection between the master station and the plurality of slave stations is the same as the conventional configuration shown in FIG.

FIG. 1 is a block diagram of a transmission system of a slave station of an automatic light reception level measuring system according to the present invention. It should be noted that the slave station is composed of three stations as an example, but is not limited to this, and the number of stations is arbitrary.

The slave stations 1 (1-1 to 1-3) generate a main signal S1 and output the logic circuit section 2, and the main signal S1.
An oscillator 3 (or a frequency multiplying circuit) which generates and outputs a received light level measuring signal S2 having a frequency n × f (Hz) (n is a positive integer) which is a positive multiple of the frequency f. A selector 4 which selects and outputs S1 or S2 by a selection signal S3 from the master station, and an electric which converts the signal S1 or S2 output from this selector 4 into an optical signal and outputs the optical signal to the optical fiber transmission lines 107 to 109. A light conversion unit (hereinafter referred to as E / O) 5.

FIG. 2 is a block diagram of the receiving system of the master station of the automatic light receiving level measuring system according to the present invention. The parent station consists of one station.

The master station 11 receives the main signal S1 and the reception level measuring signal S2 input via the optical branching device 105, and converts the received signal into an electric signal (hereinafter referred to as O / E converter). 12), a low-pass filter (hereinafter referred to as LPF) 13 having a cutoff frequency 2f, a 3R processing unit 14 that performs equalization, reproduction, and identification processing of an input signal,
A logic circuit unit 15 to which the signal processed by the 3R processing unit 14 is input, and a bandpass filter (hereinafter referred to as BPF) 16 that passes a signal having a constant bandwidth centered on a frequency of n × f (Hz) 16. A peak detector 17 for detecting the peak voltage of the output signal of the BPF 16, and A for digitally converting the signal output from the peak detector 17.
A / D converter (hereinafter referred to as A / D) 18 and this A / D
A central processing unit (hereinafter referred to as CPU) 19 for processing the signal digitally converted by 18.

FIG. 3 is a schematic explanatory diagram of a reception data format in the master station reception system. The same figure (A) is a slave station 1-1.
1 to 3 show the case of normal operation. Usually, the main signal of the slave station 1-1 is a, the main signal of the slave station 1-2 is b, the main signal of the slave station 1-3 is c, and the main signal is received by the master station in a time division manner.

On the other hand, FIG. 3B shows the case where the light receiving level measurement is controlled only for the slave stations 1-3. In this case, the main signal of the slave station 1-1 is a and the slave station 1-2 is as shown in FIG.
The main signal of is received by time division like b
The light reception level measuring signal c ′ of −3 is received as continuous light instead of time division. Therefore, on the time axis, the slave station 1
The main signal a of -1 and the main signal b of the slave station 1-2 are overlapped with the data areas, and the light reception level measurement signal c'of the slave station 1-3 is received.

FIG. 4 is a waveform diagram showing the relationship between the main signal and the received light level measuring signal. In the figure (A), the main signal S1 (a,
signal of b and c). Frequency f (Hz)
Of the digital data. In the figure, the data of 101010 ... Is shown, but this is an example, for example, 10110.
Any data such as ... may be used.

FIG. 3B shows the light reception level measuring signal S2.
(C ') is shown. It is a rectangular wave having a frequency of n × f (Hz). In this embodiment, n = 3 as an example.

FIG. 3C shows a waveform received by the master station 11. At the master station, the main signal S1 and the received light level measurement signal S2
And a superimposed signal of is received.

As will be described later, FIG. 3D is a waveform diagram of the peak voltage S4 of the received light level measuring signal S2.

Next, the operation of the automatic received light level measuring system will be described with reference to FIGS.

Select from the master station 11 to the selector 4 of the slave station 1 (1-1 to 1-3) via the optical fiber transmission line 106, the optical branching device 105, and the optical fiber transmission lines 107 to 109. The signal S3 is input.

If the selection signal S is transmitted to the slave station 1-3, the selector 4 of the slave station 1-3 selects the received light level measurement signal S2 (c ') and outputs it to the E / O5. To do. Upon receiving this, the E / O 5 converts the received light level measurement signal S2 (c ') into an optical signal to convert the optical fiber transmission line 10
9 is sent.

On the other hand, the slave stations 1-1 and 1-2 to which the selection signal S3 is not transmitted select the main signal S1 (a, b) and convert the main signal S1 (a, b) into an optical signal. It is sent to the optical fiber transmission lines 107 and 108.

The operation of the master station which has received the main signal S1 (a, b) and the received light level measuring signal S2 (c ') is as follows.

First, the optical signal is converted into an electric signal by the O / E 12. Next, LPF 13 (cutoff frequency 2 × f (H
z). ) Signal S2 (c ') for measuring received light level
Is removed and only the main signal S1 (a, b) is output. Then, the main signal S1 (a, b) is subjected to equalization, reproduction and identification processing similar to the conventional one in the 3R processing unit 14. Therefore,
In the logic circuit section 15, only the main signal S1 (a, b) component is input as usual.

On the other hand, the BPF 16 (pass frequency 3 × f (H
z)) performs filtering centered on the frequency 3 × f (Hz). By this filtering, the main signal S1
Since (a, b) is removed, only the received light level measurement signal S2 (c ') is input to the peak detector 17.

The received light level measurement signal S2 (c ') input to the peak detector 17 is treated as analog information. That is, the higher the light reception level of the light actually received by the O / E 12, the higher the input voltage to the peak detection unit 17. In the peak detection unit 17, a conventional peak hold circuit or the like is used to suppress fluctuations in the input voltage and hold (hold) the maximum voltage at the time of input to A / D1.
A constant voltage is output to 8. This peak detector 17
The waveform of the output signal S4 is shown in FIG.

FIG. 5 is a characteristic diagram showing the relationship between the received light level input to the O / E 12 and the output voltage of the peak detector 17. As shown in FIG.
Is proportional to the output voltage of.

The A / D 18 converts the analog signal input from the peak detector 17 into a digital binary signal.

The CPU 19 performs the inverse conversion processing from the digital signal input to the CPU 19 by giving the information shown in the characteristic diagram of FIG. 5 in advance, and calculates the light receiving level of the optical signal input to the O / E 12. To do. For example, CP
When the input at U19 is the Q value of the signal S4 in FIG. 5, the CPU 19 can calculate the value P as the actual optical input level of the O / E 12.

Next, the remote control system of the master station will be described. FIG. 6 is a block diagram of the remote control system of the master station.

The remote control system of the master station comprises a monitoring device 21 for monitoring the master station 11, a transmission system of the master station 11, and a transmission system and a reception system of the slave station 1.

The transmission system of the master station includes a command decoding unit 22 for decoding the command S11 from the monitoring device 21, and a superposition unit 23 for superposing the test command S12 decoded by the command decoding unit 22 on the transmission data S13. And an E / O 24 for converting the superimposed signal into an optical signal.

The transmission system of the slave station 1 has an O / E 31 for converting an optical signal input via the optical transmission path 111, the optical branching device 105 and the optical transmission path 112 into an electric signal, and an electric signal. It comprises a separation unit 32 that separates a signal into a test command S12 and received data (same as transmission data) S13, and a test command decoding unit 33 that decodes the test command S12. The selection output from the test command decoding unit 33 The signal S3 is input to the selector 4 of the transmission system and controls the selector 4.

The selector 4, the logic circuit section 2, the oscillator 3, and the E / O 5 of the receiving system are the same as those in FIG.

Next, the operation will be described. When the command S11 is input to the command decoding unit 22 from the monitoring device, the command decoding unit 22 decodes the command S11. Now, assuming that the command S11 is the received light level measurement command (test command) S12, the command decoding unit 22 reads the test command S12.

Then, the read test command S
12 is superimposed on the transmission data S13 by the superimposing unit 23, and E /
Input to O24. The E / O 24 converts this superimposed signal into an optical signal, and the optical fiber transmission line 111 and the optical branching device 105.
And to the slave station 1 via the optical fiber transmission line 112.

The slave station 1 converts this superposed signal into an electric signal by the O / E 31 and inputs it to the separating section 32. The separation unit 32 uses the superimposed signal as the reception data S13 and the test command S12.
And the test command S12 is input to the decoding unit 33.

The decoding section 33 decodes that the input signal is the test command S12 and outputs the selection signal S3.

The selection signal S3 is input to the selector 4, and the selector 4 selects the light reception level measurement signal S2 (c ') from the oscillator 3. Then, the selected light reception level measurement signal S2 (c ') is transmitted to the master station 11 via the E / O5, the optical fiber transmission path 109, and the like.

Then, the received light level measuring signal S2
As described above, the master station 11 measures the received light level based on (c ').

[0050]

According to the present invention, the master station separates the reception signal from each slave station into the main signal and the reception level measurement signal, and the reception level measurement signal separated by this separation means. Since the signal conversion means for converting a signal into an analog level signal is included, it is possible to measure the received light level without interrupting communication between the slave station and the master station.

Further, since the remote control means for causing the master station to measure the received light level by remote control is provided, it is not necessary for the maintenance person to directly operate the equipment, and therefore erroneous operation can be reduced.

[Brief description of drawings]

FIG. 1 is a transmission system configuration diagram of a slave station of an automatic light reception level measurement system according to the present invention.

FIG. 2 is a block diagram of a receiving system of a master station of the system.

FIG. 3 is a schematic explanatory diagram of a reception data format in a master station reception system of the system.

FIG. 4 is a waveform diagram showing a relationship between a main signal and a light receiving level measuring signal of the system.

FIG. 5 is a characteristic diagram showing the relationship between the light receiving level input to the O / E of the system and the output voltage of the peak detection unit.

FIG. 6 is a configuration diagram of a remote control system of a master station of the system.

FIG. 7 is a configuration diagram of a star-shaped optical branching system.

[Explanation of symbols]

 1 Slave Station 2 Logic Circuit Section 3 Oscillator 4 Selector 11 Master Station 13 Low-pass Filter 16 Band-pass Filter 17 Peak Detecting Section 21 Monitoring Device 22 Command Decoding Section 23 Superimposing Section 32 Separating Section 33 Test Command Decoding Section

Claims (6)

[Claims] 1. An automatic light reception level measuring system for an optical branching system, wherein one master station and a plurality of slave stations are connected in a star shape, and the master station measures the light reception level of light from each slave station. The master station separates the reception signal from each slave station into a main signal and a reception level measurement signal, and a signal for converting the reception level measurement signal separated by the separation means into an analog level signal. An automatic measuring system for a received light level of an optical branching system, comprising: a converting means. 2. The main signal is generated by the slave station by a main signal generating means for generating the main signal, a reception level measuring signal generating means for generating the reception level measuring signal, and a control signal from the master station. Or a selective output means for selecting and outputting the reception level measuring signal, and an automatic light receiving level measuring system for an optical branching system. 3. The light receiving level of the optical branching system according to claim 1, wherein the main signal is a signal that is time-divisionally output, and the reception level measuring signal is a signal that is continuously output. Automatic measurement system. 4. The light receiving system of claim 1, wherein the reception level measuring signal is a clock pulse having a frequency that is a positive multiple of the clock frequency of the main signal. Level automatic measurement system. 5. The master station has superimposing output means for superimposing and outputting the control signal for measuring the reception level on a main signal addressed to the slave station, and the slave station outputs the superposed signal to the main signal. 5. The automatic light reception level measuring system for an optical branching system according to claim 1, further comprising a second separating means for separating the control signal and the control signal. 6. The automatic light receiving level measuring system for an optical branching system according to claim 1, further comprising remote operating means for causing the master station to measure a light receiving level by remote operation.