KR20040009179A - optical channel monitoring device of the WDM system - Google Patents

Abstract

PURPOSE: A device for monitoring an optical channel of a WDM system is provided to convert an optical current signal of the optical channel through a current/voltage converter, and to decide a detection signal through a comparator, then to output an alarm signal showing whether the optical channel fails, thereby easily monitoring an optical output. CONSTITUTION: A photo diode(1) detects an optical output signal from an optical channel. A current/voltage converter(2) converts a current signal in accordance with the optical output signal into a voltage signal, and outputs the voltage signal. The first buffer(3) buffers the detected voltage signal in order to minimize impedance influence. An inverter(4) inverts the detected voltage signal whose phase is inverted to a signal at a detection point and an in-phase. The second buffer(5) buffers the detected voltage signal in order to minimize impedance influence. An A/D converter(6) converts an analog optical detection signal outputted through the second buffer(5) into a digital signal, and outputs the digital signal.

Description

Optical channel monitoring device of the WDM system

The present invention relates to an optical channel monitoring device of the UDM system, and in particular, converts and outputs a photocurrent signal of a detected optical channel through a current / voltage converter and determines whether the optical channel is abnormal by determining the output detection signal through a comparator. The present invention relates to an optical channel monitoring apparatus of the DB system that outputs an alarm signal.

In general, a system using an optical multiplexing system is a system that transmits through a single transmission path by appropriately combining transmission information from a plurality of information sources at a transmitter in order to improve transmission efficiency of a transmission system, and recovers original individual transmission information at a receiver. Point to. In particular, this type of system is an essential important technology for realizing ultra-high speed optical communication system using optical fiber of broadband transmission characteristics. That is, the speed of data that can be transmitted through one optical transmission channel is effectively limited to the speed of 10Gbps because of the processing speed limitation of the electronic device.

The optical multiplexing scheme includes optical time division multiplexing (OTDM), optical code division multiplexing (OCDM), wavelength division multiplexing (WDM), and optical. It may be divided into an optical frequency division multiplexing (OFDM). The WDM method is a method of dividing each input channel into different wavelength bands and transmitting the signals into 1.3 μm and 1.5 μm wavelength bands. However, in recent years, the WDM method can be used as the basis for mass communication. In order to increase the transmission capacity, a dense WDM (DWDM) technology has been developed that can be transmitted by dividing it into several narrow wavelength bands in the 1.55㎛ wavelength band.

At this time, these DWDM systems individually use the optical wavelength stabilization circuit to stabilize the wavelength of each transmission laser light source, the optical wavelength stabilization circuit plays a very important role in suppressing crosstalk between optical channels. For example, such an optical wavelength stabilization circuit suppresses the wavelength fluctuation of the transmission laser light source within ± 20 pm when the wavelength interval between the optical channels is 0.4 nm, thereby smoothly performing optical transmission.

Then, referring to the optical channel monitor of the conventional WDM system with reference to Figure 1, the photodiode 70 for detecting the optical output signal in the optical channel of the same point as the main line or switching board of the WDM system, and the photodiode A log amplifier 71 for outputting an exponential current signal according to the optical output signal output from the 70 as a linear scale log voltage signal, and a reference for providing a reference current to the log amplifier 71. A first adder 73 connected to a current supply unit 72 and an output terminal of the log amplifier 71 to correct an optical output signal of the log amplifier 71 to a main line output level, and the first adder 73 A reference for supplying a reference voltage signal to the signal corrector 75 for correcting the optical output signal output from the A / D converter 74 to the recognition level of the A / D converter 74 and the first adder 73 and the signal corrector 75. The voltage supply unit 76 is formed.

The signal corrector 75 may include a first buffer 77 for buffering an optical output signal of the first adder 73 and an A / D converter 74 for outputting the output signal of the first buffer 77. A multiplier 78 for adjusting the input level signal of the multiplier 78 and a reference voltage provided from the reference voltage supply unit 76 to the optical output signal of the multiplier 78 as an input level signal of the A / D converter 74. It consists of a 2nd adder 79 which outputs.

In addition, the reference voltage supply unit 76 buffers the voltage regulator 80 generating the reference voltage and the reference voltage output from the voltage regulator 80 to output the non-inverting terminal of the first adder 73. A second buffer 81 and a third buffer 82 for buffering the reference voltage output from the voltage regulator 80 to output to the non-inverting terminal of the second adder 79.

Here, the first to second adders 73 and 79, the first to third buffers 81, 77, 82, and the multiplier 78 are configured as OP amplifiers.

In addition, an A / D converter 74 is connected to an output terminal of the second adder 79, and a microcomputer 84 is connected to an output terminal of the A / D converter 74 via an FPGA 83.

Meanwhile, referring to the operation of the optical channel monitor of the conventional WDM system, when it is necessary to detect and monitor the optical output signal in the optical channel at the point such as the main line or the switching board of the WDM system, tap on the optical channel at the corresponding point. After the photodiode 70 is installed, an optical output signal is detected. At this time, the photodiode 70 detects an optical output signal from the installed optical channel and outputs a detection current signal proportional to the detected optical output signal to the log amplifier 71. Then, the log amplifier 71 converts an exponential current signal input from the photodiode 70 into a log voltage signal on a linear scale using the reference current signal supplied from the reference current supply unit 72. The signal is converted and output to the first adder 73.

The first adder 73 performs level correction so that the light output signal of the log amplifier 71 matches the light output level flowing to the main line of the WDM system, and then corrects the corrected light output signal. To the first buffer 77 of 75). In addition, the first buffer 77 of the signal corrector 75 buffers the optical output signal of the first adder 73 to minimize the influence of impedance and outputs the result to the multiplier 78. In this case, the multiplier 78 adjusts the input optical output signal to the input level of the A / D converter 74. That is, since the output level of the optical output signal is considerably larger than the input level of the A / D converter 74, a constant value, for example, the optical output signal is 8 [V] and the A / D converter 74 Assuming that the input level is 4 [V], the optical output signal voltage is multiplied by 1/2 [V] to be output to the second adder 79. Then, the second adder 79 adds the reference voltage provided from the third buffer 82 of the reference voltage supply unit 76 to the optical output signal of the multiplier 78 to input the A / D converter 74. The signal is converted to a level signal and then output to the A / D converter 74.

The A / D converter 74 converts the analog optical output signal output from the second adder 79 of the signal compensator 75 into a digital signal and outputs the digital signal to the FPGA 83. In addition, the FPGA 83 stores therein a digital optical output signal output from the A / D converter 74. Then, the microcomputer 84 of the WDM system polls the optical output signal for the point currently monitored from the FPGA 83 and displays it on the display (not shown), thereby monitoring the optical output of the corresponding point.

However, the conventional optical channel monitor of the WDM system as described above is expensive because the log amplifier is installed on the main line of the WDM system or the optical channel of the switching board to detect the optical output signal, the manufacturing cost of the optical channel monitoring apparatus using such a log amplifier In addition, when the log amplifier is used for monitoring the optical output signal, a separate additional element for reducing the input level of the A / D converter at the rear of the log amplifier must be installed in a certain space. There was also a problem that the spatial design of the optical channel monitor device is considerably degraded.

Accordingly, the present invention has been invented to solve the above-mentioned general problems, and converts the photocurrent signal of the detected optical channel through a current / voltage converter and outputs it, and determines the output signal through the comparator to determine whether the optical channel is abnormal. By outputting an alarm signal to notify the light output using an inexpensive current / voltage converter can easily monitor the optical output according to the optical channel monitoring device of the DUU DM system that significantly reduces the manufacturing cost of the optical channel monitoring device accordingly There is a purpose.

Another object of the present invention is that since the size of the current / voltage converter is smaller than the conventional log amplifier, the space design of the optical channel monitoring apparatus can have a considerable margin, so the space design of the optical channel monitoring apparatus is also significantly improved. An optical channel monitoring apparatus is provided.

The present invention for achieving the above object is the phase of the photodiode for detecting the optical output signal in the optical channel of a certain point of the WDM system, and the exponential current signal according to the optical output signal output from the photodiode A current / voltage converter converting and outputting a voltage signal, a first buffer buffering a detection voltage signal according to the optical output output from the current / voltage converter to minimize the influence of impedance, and the light output from the first buffer An inverter for inverting a detection voltage signal having an inverted phase according to an output in phase with a signal at a detection point, a second buffer for buffering the detection voltage signal output from the inverter to minimize impedance influence, and the second buffer Dubble consisting of A / D converter that converts analog photodetection signal output through digital signal to digital signal It provides an optical channel monitoring device of UDM system.

1 is an explanatory diagram illustrating an optical channel monitoring apparatus of a conventional WDM system.

2 is an explanatory diagram illustrating an optical channel monitoring apparatus of the present invention.

<Detailed Description of Codes>

1: photodiode 2: current / voltage converter

3: first buffer 4: inverter

5: second buffer 6: A / D converter

7: comparator 8: reference voltage supply

9: FPGA 10: Microcomputer

R1-R3: Resistance VR: Variable resistor

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 2, the apparatus of the present invention is a photodiode 1 for detecting an optical output signal at an optical channel at a certain point of the WDM system, for example, a main line or a switching board, and an output from the photodiode 1. A current / voltage converter 2 for converting an exponential current signal according to the optical output signal converted into a voltage signal having an inverted phase and outputting the detected voltage signal according to the optical output output from the current / voltage converter 2; Inverting the first buffer (3) buffering to minimize the impact of the impedance, and the inverted detection voltage signal according to the optical output output from the first buffer (3) in phase with the signal of the detection point (4), a second buffer (5) for buffering the detected voltage signal output from the inverter (4) to minimize the influence of impedance, and an optical photodetection signal output through the second buffer (5). The A / D converter 6 converts the call into a digital signal and outputs the light, and the light detection signal of the second buffer 5 is compared with the reference voltage signal to determine whether there is an abnormality in the light output and according to the determination result. Comparator 7 for outputting an alarm signal and a reference voltage supply unit 8 for providing a reference voltage signal to the comparator (7).

Here, the current / voltage converter 2, the first buffer 3, the inverter 4, the second buffer 5 and the comparator 7 are composed of an OP amplifier.

In addition, the output signals of the comparator 7 and the second buffer 5 may be stored in the FPGA 9.

A resistor R1 and a variable resistor VR are connected in series between the inverting terminal of the OP amplifier and the output terminal of the current / voltage converter 2, and a photodiode 1 is connected to the inverting terminal of the OP amplifier. The non-inverting terminal of the OP amplifier is grounded. In addition, a loop line is connected between the output terminal of the first buffer 3 and the inverting terminal, and the output terminal of the current / voltage converter 2 is connected to the non-inverting terminal of the first buffer 3. A resistor R2 is connected between the inverting terminal and the output terminal of the inverter 4, the inverting terminal of the inverter 4 is grounded, and a resistor R3 is provided to the inverting terminal of the inverter 4. Via the output terminal of the first buffer 3 is connected. In addition, a loop line is connected between the output terminal of the second buffer 5 and the inverting terminal, and the output terminal of the inverter 4 is connected to the non-inverting terminal of the second buffer 5.

Next, the operation and effect of the apparatus of the present invention as described above will be described.

The apparatus of the present invention first, when it is necessary to detect and monitor the optical output signal in the optical channel of the point, such as the main line or switching board of the WDM system, make a tap on the optical channel of the point, and then install a photodiode (1) Detect the output signal. At this time, the photodiode 1 detects an optical output signal from the installed optical channel and outputs an exponential detection current signal proportional to the detected optical output signal to the current / voltage converter 2. Then, the current / voltage converter 2 converts the exponential current signal input from the photodiode 1 into a voltage signal according to the range of the set resistors R1 and VR to the first buffer 3. Output

In addition, the first buffer 3 buffers the detected voltage signal according to the optical output output from the current / voltage converter 2 to minimize the influence of impedance, and then outputs it to the inverter 4. At this time, the inverter 4 inverts the detection voltage signal whose phase is inverted according to the light output from the first buffer 3 in phase with the signal at the detection point and outputs it to the second buffer 5. The second buffer 5 buffers the detected voltage signal output from the inverter 4 to minimize the influence of impedance, and then outputs it to the non-inverting terminal of the A / D converter 6 and the comparator 7.

Then, the A / D converter 6 converts the analog photodetection signal output through the second buffer 5 into a digital signal and outputs the digital signal to the FPGA 9. Then, the FPGA 9 stores therein a digital optical output signal output from the A / D converter 6.

In this case, the microcomputer 10 of the WDM system polls an optical output signal for a point currently monitored from the FPGA 9 and displays it on a display (not shown) to monitor the optical output of the corresponding point. .

On the other hand, the comparator 7 compares the optical output voltage signal for the current monitoring point input from the second buffer 5 with the reference voltage provided from the reference voltage supply unit 8. At this time, the comparator 7 does not generate an alarm signal if the currently detected light output detection voltage signal is higher than the reference voltage. However, if the currently detected optical output detection voltage signal is lower than the reference voltage, the comparator 7 determines that the optical transmission of the WDM system is abnormal and transmits an alarm signal to the FPGA 9. Then, the microcomputer 10 polls the alarm signal in the FPGA 9 to generate an alarm signal to the outside.

Thus, the administrator or others monitoring the WDM system may hear or view this alert signal and take appropriate countermeasures.

As described above, the present invention converts and outputs a photocurrent signal of a detected optical channel through a current / voltage converter, and outputs an alarm signal indicating whether an optical channel is abnormal by determining the output detection signal through a comparator. Since the light output can be easily monitored using a current / voltage converter, the manufacturing cost of the optical channel monitoring apparatus is significantly reduced.

In addition, according to the present invention, since the size of the current / voltage converter is smaller than the conventional log amplifier, the space design of the optical channel monitoring apparatus can have a considerable margin, and accordingly, the spatial design of the optical channel monitoring apparatus is also significantly improved.

Claims (3)

A photodiode for detecting an optical output signal in an optical channel at a certain point of the WDM system, and a current / voltage converter for converting an exponential current signal according to the optical output signal outputted from the photodiode into a voltage signal having an inverted phase. And a first buffer for buffering a detection voltage signal according to the optical output output from the current / voltage converter to minimize an impedance effect, and a detection voltage signal having a phase inverted according to the optical output output from the first buffer. An inverter that inverts in phase with the signal at the detection point, a second buffer buffering the detected voltage signal output from the inverter to minimize the influence of impedance, and a digital photodetection signal output through the second buffer. The optical channel of the DB system, characterized in that composed of the A / D converter to convert the signal to output Monitoring device. The method of claim 1, wherein the second buffer is connected to a comparator for comparing an optical detection signal according to a reference voltage signal to determine whether there is an abnormality in the optical output and outputting an alarm signal according to the determination result. The channel monitoring device of the VDM System. The apparatus of claim 1, wherein the current / voltage converter is configured as an OP amplifier.