KR100280656B1 - Defect point generation / release detection method and apparatus of optical transmission system - Google Patents

Abstract

The present invention relates to a method and apparatus for detecting and releasing a defect point of an optical transmission system, which protects a manufacturer from a light source during cutting and disconnection of an optical line and completely recovers without affecting the performance of the system upon release of the defect. You can do it.

ALS-LOS detecting means and SF-LOS detecting means for detecting the power level of the input light and the power level after the input light is pre-converted at the optical connection part and the digital connection part of the front end optical amplifier receiving end, respectively; ALS recovery detecting means for detecting a release of a defect point by detecting a power level of input light at an optical connection portion of a post-end optical amplifier transmitting end; Determining the occurrence of a defect point in accordance with the signal state detected by the ALS-LOS detection means and the SF-LOS detection means to execute a light source shut-off (ALS), and release the defect point according to the signal state detected by the ALS recovery detection means. Defect point generation / release detection apparatus including an optical power control means for determining the recovery of the ALS; And comparing the detected two power levels with a given threshold and declaring ALS-LOS or SF-LOS, respectively, executing ALS, and repeatedly recovering the trickling signal for a predetermined time at a predetermined time interval in the ALS state. A defect point generation / release detection method for detecting defect release is provided.

Description

Defect point detecting method and system for Automatic Laser Shutdown in ultra-long haul

The present invention relates to an apparatus and method for detecting and releasing a defect point for automatically blocking a light source in an optical transmission system, and in particular, accurately distinguishing whether a loss of input light appearing at a receiver is caused by a light source blocking or a light path defect. In order to recover the blocked state of the light source, it is possible to distinguish between the alarm by the light source blocking or the light source blocking even when detecting the defect point.

Conventional optical transmission systems include Automatic Laser Shutdown (ALS) devices for the purpose of protecting the operator (or installation and manufacturer) from light sources exposed in the event of a defect caused by cutting of the optical path or opening or removing the optical connector. Is provided. The automatic light source blocking device detects the intensity of the optical power input to the light receiving unit, processes a command for setting a defect point generation due to a loss of signal (hereinafter referred to as LOS), and automatically cuts off the light source. Similarly, when recovering from the state, it detects the intensity of the optical power input to the optical receiver and processes a command to recover the defect point release.

In such a conventional optical transmission system (including an optical amplifier embedded system), a defect point detection method is the same as that of FIGS. 1A and 1B described above.

First, FIG. 1A is a flowchart illustrating a method for detecting a defect point in a system using a 3R (retiming, reshaping, reframing) optical relay without a conventional optical amplifier. Referring to FIG. 1A, the flow rate of the input optical power P is measured at the receiving end (S111), and a comparison is made at a value greater than an arbitrary reference value (eg, −28 μm) (S112). . As a result of the comparison, when the intensity of the optical power is greater than -28 dBm, input light is again received (S111), and if it is small, it is again compared whether the optical power is greater than -40 ± 5 dBm (S113). As a result of the comparison, when the optical power is larger than -40 ± 5 dBm, the input light is received again after error processing (S114), and when the light power is small, the input light is received again after the LOS processing (S115). The process of determining whether there is a defect is repeated. When the LOS is processed, the fault alarm LOS is declared as the intensity of the input optical power. The declaration of this fault alarm LOS indicates that the received optical power is less than -40 ± 5 dBm and also means that the received optical power is rarely reached as a radio signal.

1B is a flowchart illustrating a method for detecting a defect point of a receiver in a single channel optical transmission system having a conventional optical amplifier. Referring to FIG. 1B, the optical fiber amplifier stage measures the intensity P of the input optical power 121 and then compares whether the optical power is greater than -34 dBm (S122). As a result of the comparison, when the optical power of the input light is greater than -34 dBm, the input light is received again (S121). If the input power is small, the comparison is performed to determine whether the optical power of the input light is greater than -50 ± 5 dBm (S123). As a result of the comparison, when the optical power of the input light is larger than -50 ± 5m, the input light is received again after the error processing (S124) (S121), and if the input light is smaller, the input light is received again after the LOS processing (S125) ( S121) to repeat the process of determining whether there is a defect. In this case, as in FIG. 1A, when the processing is performed at the LOS (S125), the failure alert is declared by the intensity of the input optical power. The declaration of this fault alarm LOS indicates that the received optical power is less than -50 ± 5 dBm and also means that the received optical power is rarely reached as a radio signal.

In the defect point detection method, a LOS defined as the input light power intensity of the optical receiver is used as the defect point detection signal, and when a defect occurs, the LOS is detected due to the loss of the optical input power of the receiver.

However, the LOS can be divided into two cases according to the cause of the defect occurrence.

First, the defect of a transmitter light source is mentioned. When the light source of the transmitter is not operated for some reason, the light input power of the receiver will be hardly detected. In this case, the defect point is in the light source itself, and the LOS defined by the intensity of the input light power of the light receiving unit is not detected at all, thereby processing the LOS signal.

Next, the case where it is not a defect of a transmitter is mentioned. The light source of the transmitter operates normally but the LOS of the input optical power of the receiver is detected. The receiving end measures the intensity of the input light power, compares the detected intensity of the input light power with a predetermined threshold value, and determines whether or not the fault alarm is based on the comparison result to declare a fault alarm. As a result of the comparison, when the detected intensity of the input light power is smaller than a predetermined threshold, ALS is executed in the transmitter to block the light source of the transmitter.

However, in the conventional optical transmission system, since the cause of defects occurring at the receiving end is not distinguished, the LOS appearing at the receiving unit does not accurately distinguish between the LOS due to the light source blocking and the LOS due to the optical path defect. However, it only declares a fault alarm defined by the intensity of the input optical power, and also detects the release of a defect point with the intensity of the input optical power and processes a recovery command when recovering from the automatic light shut-off state. Alerts due to line faults and those triggered by ALS are indistinguishable. Therefore, the ALS execution and recovery commands are not processed, and defect detection points are not correctly distinguished even when the defect release is detected.

Accordingly, the present invention has been made to solve the above problems, and when detecting a defect point for the light source auto shut-off (ALS) in the optical transmission system, it is possible to distinguish between the alarm due to the optical path defect and the alarm due to ALS execution, In addition, the present invention provides a method and apparatus for detecting and releasing a defect point of an optical transmission system capable of recovering a light source interruption state by accurately distinguishing a defect point even when detecting a defect release.

In one embodiment of the present invention for achieving the above object, in the apparatus for detecting the occurrence / release of a defect point for automatic blocking and repair of the light source of the optical transmission system, detecting the power level of the input light at the optical connection of the receiver of the front end optical amplifier ALS-LOS detection means; SF-LOS detecting means for detecting a power level after the input light is converted / pre-converted at a digital connection of a front end optical amplifier receiving end; ALS recovery detecting means for detecting a release of a defect point by detecting a power level of input light at an optical connection portion of a post-end optical amplifier transmitting end; Determining the occurrence of a defect point in accordance with the signal state detected by the ALS-LOS detection means and the SF-LOS detection means to execute a light source shut-off (ALS), and release the defect point according to the signal state detected by the ALS recovery detection means. And an optical power control means for recovering the ALS by determining the defect.

In another embodiment of the present invention for achieving the above object in the method for detecting the generation / release of a defect point for automatic blocking and repair of the light source of the optical transmission system, the power of the input light at the optical connection and the digital connection of the front end of the optical amplifier receiver, respectively Detecting a level and a power level after the input light is pre-converted; Comparing the detected two power levels with a given threshold, declaring ALS-LOS or SF-LOS separately according to the comparison result, and executing ALS; And detecting a defect release by repeatedly recovering a trickling signal for a predetermined time at a predetermined time interval in the ALS state.

1A is a flowchart of a method for detecting a defect point in a 3R receiver without a conventional optical amplifier.

1B is a flowchart illustrating a method for searching for a defect point of a receiver in a system having a conventional optical amplifier.

Figure 2a is a flow chart for the light source blocking and recovery including the light experiment procedure according to the present invention

Figure 2b is a flow chart for the defect point search when using only the optical receiving module in the receiver according to the present invention

Figure 2c is a flow chart for the defect point search when using the optical amplifier in the receiver according to the present invention

3 is a block diagram of a booster amplifier for ALS recovery in a rear-end optical amplifier transmitter according to the present invention.

Figure 4 is an APC block diagram by Trickling for defect release search in accordance with the present invention

5 is a block diagram of a preamplifier for defect detection in the shear optical amplifier receiver according to the present invention

6 is a block diagram of LOS or ALS-LOS detection in the receiver according to the present invention.

7 is a reference diagram illustrating a signal definition according to an input light level of an optical receiver;

<Explanation of symbols for the main parts of the drawings>

314, 326, 410, 610, 514, 528: photodiode

316, 516: monitor control section 318, 518: pumping laser

312, 324, 512, 526: Optical coupler 313, 323, 513, 523: Unidirectional

320, 520: wavelength division multiplexer (WDM) 322, 522: erbium doped optical fiber (EDF)

328, 530: Automatic power control (APC) unit 412, 612: Differentiator

414, 614: comparator 416: pumping laser current control

616: ALS-LOS detection unit

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

Figure 2a shows a flow chart for the light source blocking and recovery including the light experiment procedure according to the present invention. Referring to FIG. 2A, the flow chart will be described with reference to FIG. 2A. In operation S210, it is determined whether an optical signal is received at the terminal (S211). At this time, if a signal is received from the receiver, it returns to the first step of the ALS operation state (S210) to make sure the ALS is operated. If the signal is not received at the end, it is determined whether the signal transmission loss t continues for more than 550 ± 50 ms (S212). At this time, if the signal transmission loss is smaller than the time, it returns to the first step ALS operating state (S210). If greater than that time, ALS is executed (S213). In other words, LOS status defects continue for more than 550 ± 50 msec when cutting into the line or opening / detaching the optical connector and automatically shut off the light source unless the counter transmitter fails.

In the ALS execution state, the present invention uses a trickling method as a method for recovering an automatically blocked light source. This trickling approach not only facilitates ALS setup and recovery, but also enables ALS recovery without affecting system performance and reliability. This trickling process is performed in one of three cases, namely, automatic recovery (S214), manual recovery (S215), and experimental manual recovery (S216), as shown in FIG. Is restored.

First, in the case of automatic recovery (S214), the LOS release is maintained for more than 550 ± 50 msec at the optical receiver by repeating the light source recovery (S218) for 2 ± 0.25sec at 60-300sec interval (S217) in the automatic light source blocking state. When the fault release search is completed, the ALS state is recovered.

Next, in the case of manual recovery (S215), when the LOS release is maintained for more than 550 ± 50msec at the optical receiver by recovering the light source for 2 ± 0.25msec (S218-1) in the auto-off state of the light source, defect release detection is completed and ALS is completed. Recover from state

In addition, in the case of the manual manual recovery (S216), if the LOS release is maintained for more than 550 ± 50 msec at the optical receiver 219 by recovering the light source for 90 ± 10 sec, the defect release search is completed and recovered in the ALS state.

Through the above-described process, the light transmission system in the automatic light source blocking state is completed in the automatic light source blocking state through one of the above automatic recovery (S214), manual recovery (S215), and test manual recovery (S216). At this time, the manual recovery (S215) or the trial manual recovery (S216) may have a higher priority by the operator setting than the automatic recovery (S214).

2B and 2C show flowcharts showing a detection method of SF-LOS and ALS-LOS. In this case, SF-LOS is defined as LOS due to optical path defect occurrence, and ALS-LOS is defined as LOS due to ALS setting. The SF-LOS and ALS-LOS are detected at the digital and optical planes, respectively, to facilitate detection of defect release during trickling.

Referring now to each figure, Figure 2b shows a defect point search flow chart when using only the optical receiving module in the receiver. The optical power input to the receiver may be detected by the CDR of the ORX (S220), and detected by the photodiode PD (S227). First, when the input light is detected by the CDR of the ORX (S220), it is compared (S221) whether the detection level of the input optical power is greater than -28 dBm. As a result of the comparison at this time, if the detection level of the input optical power is greater than -28 dBm, it is processed as normal optical power (S224), and if it is a small value, it is again determined whether the input optical power level is greater than -40 ± 5 dBm. Compare (S223) If the comparison result is large, error processing (S226), and if small, SF-LOS processing (S225).

When the input optical power is detected by the photodiode (S227), it is compared (S228) to see if the detection level of the input optical power is greater than -50 ± 5 dBm. If the comparison result is large, the input optical power is detected again. If the comparison is small, the ALS-LOS processing is performed (S229).

According to this flowchart of the present invention, when only the optical receiving module is used in the receiver, the ALS-LOS and the SF-LOS are clearly distinguished and detected.

Also shown in FIG. 2C is a diagram illustrating a defect point search flow diagram for the use of an optical amplifier in the receiver. Here, after detecting the optical power input to the receiver (S230), it is compared (S231) whether the optical power detection level is greater than -34 -m. If the comparison result is large, the process is processed at normal optical power (S235), and if it is small, it is again compared whether the input optical power detection level is greater than -40 ± 5 dBm (S232). If the result of the comparison is large, the error processing is performed (S233). If the level is small, the comparison is finally performed (S234) to see if the detection level of the input optical power is greater than -50 ± 5 dBm. If the comparison result is large, SF-LOS processing is finally performed (S237), and if it is small again, ALS-LOS processing (S236) is performed.

According to this flowchart of the present invention, even when an optical amplifier is used in the receiver, the ALS-LOS and the SF-LOS are clearly distinguished and detected. As shown in FIG. 2B and FIG. 2C, the apparatus according to the present invention can clearly distinguish the defects of the SF-LOS and the defects of the ALS-LOS, and also perform automatic light source blocking when detecting the LOS defects as shown in FIG. 2A. In addition, it is possible to process the recovery command by detecting the release of a defect point by the intensity of the input optical power.

3 illustrates a method of activating a reference signal for ALS recovery in a post-stage optical amplifier transmitter. The optical signal is input from the input port 310 of the optical contact surface and then enters the optical coupler 312. The optical coupler 312 detects the optical power of the wavelength division multiplexer (WDM) 320 and the input light via an isolator 313 which prevents the input optical signal from being reflected back. The photodiode 314 serves to branch by a predetermined ratio. The photodiode converts the input optical signal into an electrical signal and transmits it to the monitor controller 316. The monitor controller 316 includes an optical power detector for detecting the level of optical power of the input optical signal and the output optical signal, and a controller for controlling the pumping laser 318. The monitor controller 316 compares the optical power level of the detected output optical signal with a reference threshold value and pumps the pumping laser 318 or automatically cuts off the light source (ALS) according to the comparison result. When the pumping process is performed as a result of the comparison, the monitor controller 316 causes the pumping laser 318 to be pumped to generate an optical signal and transmit the optical signal to the WDM 320. WDM 320 combines the optical power of the pump laser diode and the power of the optical signal, and the erbium doped fiber (hereinafter referred to as EDF) 322 converts the optical energy of the pump into the optical energy of the signal. This is done so that the input optical signal has gain without electrical conversion. The optical signal via the EDF 322 is branched from the optical coupler 324 and enters the optical diode 326 through the optical output port 330 and the monitor control unit 316. The photodiode 326 converts the output optical signal into an electrical signal and inputs the electrical signal to the selective automatic power control (hereinafter referred to as APC) 328 and the monitor controller 316. The optional APC 328 then compares the input electrical signal with a reference threshold and causes the pumping laser 318 to be in the pumping state or in the blocking state depending on the comparison result.

FIG. 4 illustrates an APC scheme by Trickling for detecting defect release that may be included in the monitor controller 316 of FIG. 3. The photoelectric unit converts optical power detected by an optical diode of a transmitter into an electrical signal. (O / E) conversion unit, the pump LD power control unit for controlling the pumping laser current by comparing the output of the photoelectric conversion unit with an arbitrary threshold value. In this case, the O / E converter may include an optical diode 410 for converting the power level of the optical signal output from the transmitter into an electrical signal and a differentiator 412 for converting and outputting the output voltage of the photodiode into current. The pump LD power control unit includes a comparator 414 for comparing the electric signal from the 0 / E converter with an optional threshold value, and a pumping laser current control unit 416 for controlling the current of the pump laser according to the comparison result. ) Can be configured. In this case, the selective threshold may be selected from a steady state power having an output of +12 to +15 dBm or a trickling power having an output of 0 to +5 dBm to the pump laser 318. To control the current.

5 shows a module for detecting a defect in a shear optical amplifier receiver. The optical signal is input from the optical input port 510 and then enters the optical coupler 512. The optocoupler 512 includes a wavelength division multiplexer (WDM) 520 and an optical diode for detecting the optical power of the input light via the deflector 513 which prevents the input optical signal from being reflected back. 514) serves to branch by a certain ratio. The photodiode 514 converts the input optical signal into an electrical signal and transmits the signal to the monitor controller 516. The monitor controller 516 compares the optical power level of the detected output optical signal with a reference threshold value and pumps or automatically shuts off the pumping laser 518 according to the comparison result. When the pumping process is performed as a result of the comparison, the monitor controller 516 pumps the pumping laser 518 to generate an optical signal and transmit the generated optical signal to the WDM 520. The WDM 520 combines the optical power of the pump laser diode and the power of the optical signal, and the EDF 522 allows the energy conversion of the optical energy of the pump to the optical energy of the signal so that the input optical signal gains without electrical conversion. Have it. The optical signal via the EDF branches off the optical coupler 524 and enters the optical diode 526 through the optical output port 526 and the monitor control unit 516. The photodiode 526 converts the output optical signal into an electrical signal and inputs the electrical signal to the APC 528 and the control unit monitor 516. The APC 528 then compares the input electrical signal with a reference threshold and causes the pumping laser 518 to be in a pumping state or in a blocking state depending on the comparison result.

FIG. 6 illustrates a method for detecting an optical reception level at a receiver for detecting SF-LOS or ALS-LOS defects, which may be included in the monitor controller 516 of FIG. 5. It may include an optical power detection unit for detecting the optical power level and a pump LD power control unit for controlling the pumping laser. In particular, the drawing illustrates an ALS-LOS detection method, and compares the output of the photoelectric conversion unit with an optical threshold (O / E) conversion unit for converting optical power detected by the photodiode at the receiving end into a signal and the output of the photoelectric conversion unit with an arbitrary threshold value. Can be configured as an ALS-LOS detection unit for detecting ALS-LOS. In this case, the O / E converter is composed of a photodiode 610 and a differentiator 612 for converting the level of the input optical power into an electrical signal, and the ALS-LOS detector is provided with an electrical signal from the 0 / E converter. Comparator 614 to compare with the threshold value, and LOS detector 616 for detecting the LOS signal (-50 ± 5 dBm) in accordance with the comparison result.

In the case of performing optical transmission and optical relay using the conventional 3R method in which the optical amplifier is not used, the APC controller of the transmitter should be provided with a trickling function for detecting defect release as shown in FIG. In the digital connection, the defect state SF-LOS and the defect state ALS-LOS detection function at the optical reception interface are provided as shown in FIG.

7 is a diagram for defining an input optical signal of the optical receiver. Alarms are defined according to the magnitude of the input optical signal, where EB, SD, EBR, and LOF indicate bit errors and FL-LOS, ALS-LOS, OFA-LOS, and SV-LOS indicate failure of the optical link.

The present invention as described above can be applied to a single station or repeater unit of the SMOT-16 EDFA built-in optical transmission system, and can be applied to wavelength division multiplexing for multiple channels and optical repeaters. Applicable to export Star Mux 2500 (2.5Gbps SDH) and STM-64 (10Gbps SDH) class optical transmission system, and also applicable to light sources of class 3A, 3B or higher of IEC825-1 where safety of light source is required. There is an advantage to this being possible.

In addition, the present invention can protect the manufacturing, operation, and installer from high-intensity (Class 3A, 3B) light source when cutting the optical path and opening the optical connector in a single-channel long-distance optical transmission system (Ultra-Long Haul), when the defect is released It has the effect of ensuring the safety to be completely recovered without affecting the performance of the system, and the light source is automatically operated even when the DCC (Data Communication Channel) is not available due to the optical link defect caused by cutting the optical path or opening the optical connector. There are advantages, such as enabling blocking.

Claims (5)

In the device for detecting the occurrence / release of a defect point for automatic blocking and repair of the light source of the optical transmission system, ALS-LOS detection means for detecting the power level of the input light at the optical connection of the front end optical amplifier receiving end; SF-LOS detecting means for detecting a power level after the input light is converted / pre-converted at a digital connection of a front end optical amplifier receiving end; ALS recovery detecting means for detecting a release of a defect point by detecting a power level of input light at an optical connection portion of a post-end optical amplifier transmitting end; Determining the occurrence of a defect point in accordance with the signal state detected by the ALS-LOS detection means and the SF-LOS detection means to execute a light source shut-off (ALS), and release the defect point according to the signal state detected by the ALS recovery detection means. And an optical power control means for recovering the ALS by determining the defect. 2. The ALS-LOS detecting unit according to claim 1, wherein the ALS-LOS detecting unit declares ALS-LOS to execute ALS when the light receiving level detected at the optical receiving end is -50 ± 5 dBm or less, and executes ALS. Defect point generation / release detection device of the optical transmission system, characterized in that for automatically blocking. The optical transmission system according to claim 1, wherein the SF-LOS detecting means declares an SF-LOS when a signal level after light / pre-conversion at the optical receiver is detected to be -40 ± 5 dBm or less. Defect point generation / release detection device. 2. The apparatus of claim 1, wherein the optical power control means comprises: a light source automatic blocking unit (ALS) for blocking a light source of a transmitting optical amplifier according to signal levels input from the ALS-LOS detecting means and the SF-LOS detecting means; And a trickling unit for detecting defect release by performing trickling at a predetermined interval (delay time + duration) in a state where the light source is blocked. A method of detecting the occurrence / release of a defect point for automatically blocking and repairing a light source of a light transmission system, Detecting the power level of the input light and the power level after the input light is pre-converted at the optical connection part and the digital connection part of the front end optical amplifier receiving end, respectively; Comparing the detected two power levels with a given threshold, declaring ALS-LOS or SF-LOS separately according to the comparison result, and executing ALS; And detecting a defect release by repeatedly recovering the trickling signal for a predetermined time at a predetermined time interval in the ALS state.