Optical time domain reflectometry detection method and system for avoiding event blind area and OTDR (Optical Time Domain Reflectometry) equipment

Abstract

The invention discloses an optical time domain reflection detection method and system for avoiding an event blind area and OTDR equipment, and relates to the technical field of OTDR.According to the optical time domain reflection detection method, a second detector is additionally arranged at the grounding end of a first detector, the second detector is used for detecting an optical signal emitted by a second light source, and then when OTDR curve measurement is carried out on a to-be-detected optical fiber, the second detector is used for detecting the optical signal emitted by the second light source; a second driver can be controlled to drive a second light source to emit a compensation light signal within a predetermined saturation time interval, so that light current detected by a second detector is utilized to perform offset compensation on light current detected by a first detector, and current input into an amplification circuit is lower than a saturation threshold; therefore, an event blind area caused by saturation can be eliminated, a blind area event can be detected, no selection switch is added, introduction of extra noise is avoided, the optical fiber OTDR test accuracy is improved, and better noise performance is achieved.

Description

Technical Field

[0001] The present application relates to the field of OTDR technology, and in particular to an optical time domain reflectometry detection method, system and OTDR device that avoid event blind zones. Background Art

[0002] Optical Time-Domain Reflectometer (OTDR) technology uses a driver to drive a light source to emit laser pulses into an optical fiber. A detector detects the backscattered Rayleigh scattered and reflected signals of the laser pulses. The photocurrent detected by the detector is amplified by an analog amplifier circuit and converted into a digital signal by an analog-to-digital converter (ADC), thereby generating an OTDR measurement curve along the fiber. Analysis of the acquired OTDR measurement curve can reveal various properties of the optical fiber link, such as uniformity, defects, breaks, and connector coupling. Therefore, it can be used to measure fiber attenuation, connector loss, locate fiber fault points, and understand the loss distribution along the length of the fiber. It is an indispensable tool for optical cable construction, maintenance, and monitoring.

[0003] In practical applications, OTDRs with high dynamic range can be used to measure longer optical fibers and have a wider range of applications. According to the OTDR dynamic range calculation formula 5×log 10 (S / N) shows that if a larger dynamic range is to be obtained, such as 30dB, the signal-to-noise ratio S / N needs to be greater than 10 6 In the hardware structure, a 20-bit ADC is theoretically required to provide a 30dB OTDR dynamic range. However, the current 20-bit ADC in the industry only has low sampling rate devices, which cannot meet the needs of OTDR products. Therefore, due to the limitations of commercially available ADC products, 12-bit to 14-bit ADCs are generally used in current OTDR systems. However, this will lead to saturation and recovery problems: when the signal power of the laser pulse is relatively large, the photocurrent detected by the detector is also relatively large. When passing through the analog amplifier circuit, it is easy to cause the analog amplifier circuit to saturate. Since the recovery time after saturation of the analog amplifier circuit is relatively long, when the photocurrent detected by the detector decreases, the analog amplifier circuit cannot immediately enter the amplification state, and it takes a long saturation recovery time to enter the amplification state again. In the saturation state and saturation recovery time, it is impossible to accurately measure the OTDR curve, nor can it measure other events that may occur on the optical fiber line (such as reflection events, attenuation events). This period of time is also called the event blind zone, which affects the accuracy of the OTDR curve. For example, it is common to see the following Figure 1 The saturation of the reflective event shown and the Figure 2 The initial saturation condition is shown.

[0004] To address the event blind zone problem under high dynamic requirements, some current approaches utilize multiple analog amplifier circuits in OTDR systems and utilize a gain channel selector switch to switch between them. Typically, two analog amplifier circuits with different gains are used. When measuring an optical fiber's OTDR curve, the first measurement is performed by switching to the low-gain analog amplifier circuit, which amplifies the detector's photocurrent to produce a low-gain curve. The second measurement is then performed by switching to the high-gain analog amplifier circuit, which amplifies the detector's photocurrent to produce a high-gain curve. Finally, the near-end saturation portion of the high-gain curve is replaced with the near-end portion of the low-gain curve to create the resulting OTDR curve. However, due to the relatively low photocurrent, the additional noise introduced by the gain channel selector switch affects the OTDR's noise performance. Furthermore, even with a low-gain analog amplifier circuit, circuit saturation can still occur at very large reflection points, resulting in the event blind zone problem. Summary of the Invention

[0005] In response to the above problems and technical requirements, this application proposes an OTDR system that avoids event blind spots. The technical solution of this application is as follows:

[0006] An optical time domain reflectometry detection method for avoiding event blind zones, the optical time domain reflectometry detection method comprising:

[0007] Drive the first light source to emit a detection light signal P t The optical signal is injected into the optical fiber to be tested, and the first detector detects the optical signal returned by the optical fiber to be tested to generate a photocurrent i1(t);

[0008] The second light source is driven to emit a compensation light signal P within a predetermined saturation time interval. c The second detector connected in series with the first detector detects the light signal emitted by the second light source to generate a photocurrent i2(t) to offset and compensate the photocurrent i1(t) detected by the first detector, and then generates a current less than the saturation threshold i of the amplifier circuit. th The detection current I(t) is input into the amplifier circuit and analog-to-digital converter in sequence, where t represents time;

[0009] The OTDR curve of the optical fiber to be tested is obtained according to the output curve of the analog-to-digital converter.

[0010] A further technical solution is that the optical time domain reflectometry detection method further includes:

[0011] Drive the first light source to emit a test light signal P b Inject the optical fiber to be tested and obtain the test value curve output by the analog-to-digital converter to test the optical signal P b The power of the detection light signal P is much smaller than t The power is to ensure that the photocurrent i detected by the first detector isb (t)<i th ;

[0012] According to the test optical signal P b The test value curve obtained under the saturation time interval and the compensation optical signal P are estimated c .

[0013] Its further technical solution is to, according to the test optical signal P b The test value curve obtained under the saturation time interval and the compensation optical signal P are estimated c include:

[0014] Determine the test optical signal P b The power of the detection light signal P t The power reduction ratio K=P t / P b , according to the number of bits n of the analog-to-digital converter used, determine the upper limit of the value of the analog-to-digital converter output MAX=2 n -1;

[0015] According to the scaling ratio K, the test optical signal P b The test value curve obtained under the numerical amplification is numerically amplified, and the saturation time interval and the compensation optical signal P are estimated based on the numerical relationship between the test value curve after numerical amplification and the numerical upper limit MAX. c .

[0016] A further technical solution is to estimate the saturation time interval and the compensation optical signal P according to the numerical relationship between the test value curve after numerical amplification and the numerical upper limit MAX c include:

[0017] Determine the time interval in which the numerical value curve after numerical amplification exceeds the numerical upper limit MAX as the saturation time interval, and estimate the saturation degree of the numerical value curve after numerical amplification within the saturation time interval, and determine the compensation optical signal P according to the saturation degree within the saturation time interval. c The higher the saturation level, the more compensatory the optical signal P c The higher the power.

[0018] A further technical solution is to estimate the saturation degree of the test value curve after the numerical amplification within the saturation time interval, including:

[0019] The difference between the test value of the test value curve after numerical amplification in the saturation time interval and the upper limit MAX is calculated to obtain the difference value curve in the saturation time interval. The larger the difference value, the higher the degree of saturation.

[0020] A further technical solution is to determine the compensation light signal P according to the saturation degree within the saturation time interval. cinclude:

[0021] According to the analog-to-digital conversion logic of the analog-to-digital converter, the difference value curve in the saturation time interval is converted to obtain the photocurrent i2(t) in the saturation time interval, and according to P c (t) = i2(t) / η to obtain the compensation optical signal P in the saturation time interval c Time transformation curve P c (t);

[0022] Alternatively, the maximum value of the difference value curve within the saturation time interval is converted according to the analog-to-digital conversion logic of the analog-to-digital converter to obtain the maximum value i of the photocurrent i2(t) within the saturation time interval. 2_max , and follow P c =i 2_max / η conversion to obtain the compensation optical signal P in the saturation time interval c ;

[0023] Wherein, η is the conversion coefficient of the light signal sent by the second light source to be received by the second detector and converted into a photocurrent.

[0024] A further technical solution is that the OTDR curve of the optical fiber to be tested is obtained according to the output of the analog-to-digital converter, including:

[0025] The compensation curve in the saturation time interval is superimposed on the output curve of the analog-to-digital converter to obtain the OTDR curve of the optical fiber to be tested. The compensation curve in the saturation time interval is the compensation optical signal P detected by the second detector in the saturation time interval according to the analog-to-digital conversion logic of the analog-to-digital converter. c The obtained curve is converted from the photocurrent i2(t).

[0026] A further technical solution is to drive the second light source to emit compensation light signal P in multiple saturation time intervals during an OTDR curve detection process of the optical fiber to be tested. c The duration of any two saturation time intervals is equal or unequal; the compensation light signal P emitted by the second light source in any two saturation time intervals is equal or unequal; c The signal powers are equal or unequal.

[0027] An optical time domain reflectometry detection system for avoiding event blind zones, the optical time domain reflectometry detection system comprising:

[0028] The first control module is used to drive the first light source to emit a detection light signal P t The optical signal is injected into the optical fiber to be tested, and the first detector detects the optical signal returned by the optical fiber to be tested to generate a photocurrent i1(t);

[0029] The second controller module is used to control the second driver to drive the second light source to emit the compensation light signal P within a predetermined saturation time interval. c The second detector connected in series with the first detector detects the light signal emitted by the second light source to generate a photocurrent i2(t) to offset and compensate the photocurrent i1(t) detected by the first detector, and then generates a current less than the saturation threshold i of the amplifier circuit. th The detection current I(t) is input into the amplifier circuit and analog-to-digital converter in sequence, where t represents time;

[0030] The curve output module is used to obtain the OTDR curve of the optical fiber to be tested according to the output curve of the analog-to-digital converter.

[0031] An OTDR device for avoiding event blind zones comprises a controller, a first driver, a first light source, a second driver, a second light source, a first detector, a second detector, an amplifier circuit, and an analog-to-digital converter. The controller is connected to and controls the first driver and the second driver. The first driver is connected to and drives the first light source, and the second driver is connected to and drives the second light source. The first detector and the second detector are sequentially connected in series, and the common ends of the first and second detectors are sequentially connected to the amplifier circuit and the analog-to-digital converter and then connected to the controller. The first light source transmits an optical signal to an optical fiber to be tested, and the first detector detects an optical signal returned by the optical fiber to be tested. The second detector detects the optical signal transmitted by the second light source. The controller is used to execute the steps of the optical time domain reflectometry detection method according to the first aspect.

[0032] The beneficial technical effects of this application are:

[0033] The present application discloses an optical time domain reflectometry detection method, system, and OTDR device for avoiding event blind zones. The optical time domain reflectometry detection method utilizes a second detector to detect the optical signal of a second light source for offset compensation, thereby avoiding event blind zones caused by saturation, enabling the detection of blind zone events. Furthermore, no selection switch is added to avoid the introduction of additional noise, thereby improving the accuracy of optical fiber OTDR testing and having better noise performance.

[0034] Existing methods for gain switching through multiple analog amplifier circuits with different gains require multiple curve tests, and each curve test requires emitting multiple test pulses and averaging them many times. For example, in the case of an analog amplifier circuit with two built-in gains, two curve tests are required, and each curve test requires emitting, for example, 10,000 pulses and averaging them 10,000 times. One averaging of 100 km of optical fiber requires >1 millisecond, so one curve test takes 100 seconds. Then, a total of two curve tests take 200 seconds, which is time-consuming and inefficient. Although the optical time domain reflection detection method of the present application requires obtaining a test value curve in advance, the present application only needs to emit a pulse of test light signal and average it once when obtaining the test value curve to estimate the saturation time interval and the compensation light signal, and then perform a curve test in a compensation manner. For example, taking the example of a curve test requiring 10,000 pulses and averaging 10,000 times, the method of the present application can save about 100 seconds compared to the traditional method, thereby greatly improving efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is the output curve of the analog-to-digital converter when a reflection event saturates the existing OTDR equipment.

[0036] Figure 2 This is the output curve of the analog-to-digital converter when the existing OTDR equipment is saturated at the beginning.

[0037] Figure 3 This is a hardware structure diagram of an OTDR device according to an embodiment of the present application.

[0038] Figure 4 It is a comparison diagram of the output curve of the analog-to-digital converter under the traditional method and the output curve of the analog-to-digital converter after offset compensation according to the optical time domain reflectometry detection method of the present application.

[0039] Figure 5 It is a schematic diagram of the test value curve after numerical amplification in an example.

[0040] Figure 6 This is a structural block diagram of an optical time domain reflectometry detection system according to an embodiment of the present application. DETAILED DESCRIPTION

[0041] The specific implementation of this application will be further described below with reference to the accompanying drawings.

[0042] This application discloses an optical time domain reflection detection method for avoiding event blind zones. The hardware structure diagram of the OTDR device that implements the optical time domain reflection detection method is as follows: Figure 3As shown, the OTDR device includes a controller, a first driver 1, a first light source 2, a second driver 3, a second light source 4, a first detector 5, a second detector 6, an amplifier circuit, and an analog-to-digital converter. The actual controller is also connected to other devices such as a memory, which will not be described in detail in this application.

[0043] The controller is connected to and controls the first driver 1 and the second driver 3. The first driver 1 is connected to and drives the first light source 2, and the second driver 3 is connected to and drives the second light source 4. The first detector 5 and the second detector 6 are connected in series, the cathode of the first detector 5 is connected to a positive power supply, and the anode of the second detector 6 is connected to a negative power supply or ground, or the cathode of the first detector 5 is grounded, and the anode of the second detector 6 is connected to a negative power supply. The common end of the first detector 5 and the second detector 6 is connected to an amplifier circuit and an analog-to-digital converter in sequence and then connected to the controller. In one embodiment, the first detector 5 and the second detector 6 are both implemented using APDs (avalanche photodiodes), then the cathode of the diode of the first detector 5 is connected to a positive power supply, the anode of the diode of the first detector 5 is connected to the cathode of the diode of the second detector 6, and the anode of the diode of the second detector 6 is grounded or a negative power supply; or the cathode of the first detector 5 is grounded, and the anode of the second detector 6 is connected to a negative power supply.

[0044] The optical signal emitted by the first light source 2 (referred to as a test optical signal) is coupled to the optical fiber under test via a coupler (the coupler can be a circulator, a splitter, a spectrometer, etc.). For example, it is injected into port 1 of the circulator 7. Port 2 of the circulator 7 is connected to the optical fiber under test or injected into the spectrometer or spectrometer, and then injected into the optical fiber under test. The optical signal forms backward Rayleigh scattering and / or reflection in the optical fiber under test (which can be called a backscattered and / or reflected optical signal). The backscattered and / or reflected optical signal is detected or received by the first detector 5 through the coupler, for example, detecting the optical signal at port 3 of the circulator 7 or detecting the optical signal that returns from the optical fiber and passes through the spectrometer or spectrometer to reach the first detector. If the coupler is a circulator, the circulator 7 sequentially transmits the optical signal input from port 1 to port 2 for injection into the optical fiber under test. The circulator 7 also sequentially transmits the backward optical signal in the optical fiber under test returned from port 2 to port 3 for detection by the first detector 5. The second detector 6 detects the optical signal emitted by the second light source 4.

[0045] Based on having Figure 3 In the OTDR device of the hardware circuit shown, the controller performs the following steps to implement the optical time domain reflectometry detection method disclosed in this application:

[0046] Control the first driver 1 to drive the first light source 2 to emit a detection light signal P t Inject the optical fiber to be tested, and control the second driver 3 to drive the second light source 4 to emit the compensation optical signal P within the predetermined saturation time interval. c , the predetermined saturation time interval is i1(t)>ith The time interval, i th It is the saturation threshold of the amplifier circuit.

[0047] The detection light signal P emitted by the first light source 2 t The backward optical signal generated after being injected into the optical fiber to be tested is received by the first detector 5 and converted into a photocurrent i1(t). The current direction of the photocurrent i1(t) flows from the pull-up power supply connected to the first detector 5 to the common end of the two detectors. c When the current flowing into the amplifier circuit is the photocurrent i1(t), the photocurrent i1(t) is amplified by the amplifier circuit and then converted into a digital signal by the analog-to-digital converter ADC. At the large reflection point, since i1(t)>i th This will cause the amplifier circuit to saturate, resulting in the event blind zone being unable to detect attenuation events and reflection events.

[0048] Therefore, the present application uses the second light source 4 to emit the compensation light signal P in the saturation time interval that will lead to the event blind zone. c , compensated optical signal P c It is received by the second detector 6 and converted into a photocurrent i2(t). The current direction of the photocurrent i2(t) flows from the common terminal of the two detectors to the ground terminal. At this time, the photocurrent i2(t) detected by the second detector 6 will offset the photocurrent i1(t) detected by the first detector 5, so that the detection current I(t) flowing into the amplifier circuit is equal to i1(t)-i2(t). Therefore, as long as the size of the photocurrent i2(t) is reasonably adjusted so that the input amplifier circuit I(t) is less than i th , it is possible to avoid saturation of the amplifier circuit, thereby avoiding the event blind zone within the saturation time interval.

[0049] The offset compensation effect of the second detector can avoid the occurrence of event blind spots. At this time, the current values corresponding to the output curve of the analog-to-digital converter obtained are all less than the saturation threshold i th , and there is no event blind zone in the saturation time interval in the output curve of the analog-to-digital converter. For example, in an example, Figure 4 As shown, the first light source 2 is as follows Figure 4 (a) The emitted detection light signal P t If the photocurrent i1(t) is directly amplified and converted to digital form using conventional methods, the curve is as follows: Figure 4 As shown in (b) in Figure 4 As can be seen from (b) in this case, the output curve of the analog-to-digital converter has a time blind zone. On this basis, according to the method of the present application, the second light source 4 is used as follows Figure 4 (c) in the figure emits a compensation optical signal P during the saturation time interval. c , in the photocurrent i2( The output curve of the analog-to-digital converter under the offset compensation of t) is as follows Figure 4 As shown in (d) in the figure. Figure 4 As can be seen from (b) and (d) in FIG, the output curve after the offset compensation of the analog-to-digital converter in this application avoids the event blind zone.

[0050] As mentioned above, the output curve of the analog-to-digital converter at this time is the output curve under the offset compensation effect of the photocurrent i2(t), which cannot accurately represent the OTDR data of the optical fiber to be tested. Therefore, data restoration is required, including superimposing the compensation curve in the saturation time interval on the output curve of the analog-to-digital converter to obtain the OTDR curve of the optical fiber to be tested. The compensation curve in the saturation time interval used here is the same as the compensation optical signal P detected by the second detector in the saturation time interval. c The obtained photocurrent i2(t) corresponds to the obtained photocurrent i2(t), and specifically is a curve obtained by converting the photocurrent i2(t) within the saturation time interval according to the analog-to-digital conversion logic of the analog-to-digital converter.

[0051] In the above process, the core is to determine the compensation light signal P emitted by the second light source 4 c The start and stop time and signal power of the controller will be tested and determined in advance using the first driver 1 combined with the first light source 2, including: controlling the first driver 1 to drive the first light source 2 to emit a test light signal P b The test optical signal P emitted by the first light source 2 is injected into the optical fiber to be tested. b The backward optical signal generated after being injected into the optical fiber to be tested is received by the first detector 5 and converted into a photocurrent i b (t), photocurrent i b The current direction of (t) flows from the pull-up power supply connected to the first detector 5 to the common terminal of the two detectors. b (t) After being amplified by the amplifier circuit, it is converted by the analog-to-digital converter ADC and outputs the test value curve. The greater the power of the optical signal injected into the optical fiber to be tested, the greater the photocurrent detected by the first detector 5. Therefore, the test optical signal P used in the test is b The power of the detection light signal P is much smaller than that actually used. t The power of the photocurrent i b (t) is also small to ensure that the photocurrent i detected by the first detector 5 is b (t)<i th There will be no circuit saturation problem.

[0052] Then according to the test optical signal P b The test value curve obtained can be used to estimate the saturation time interval and compensate the optical signal P c , including: first determining the test optical signal P bThe power of the detection light signal P t The power reduction ratio K=P t / P b Then, the upper limit of the value of the analog-to-digital converter output is determined according to the number of bits n of the analog-to-digital converter used. n -1, for example, the number of bits of a 14-bit analog-to-digital converter is n=14, and the upper limit of the value output by the analog-to-digital converter is MAX=16383. b The test value curve obtained under the numerical amplification is numerically amplified, and the saturation time interval and the compensation optical signal P are estimated based on the numerical relationship between the test value curve after numerical amplification and the numerical upper limit MAX. c , specifically:

[0053] The time interval in which the numerical value curve after numerical amplification exceeds the numerical upper limit MAX is determined as the saturation time interval. For example, in an example, the scaling ratio K=100, then for the test optical signal P b After the test value curve obtained is magnified by 100, the time interval corresponding to the curve exceeding the upper limit MAX=16383 is the saturation time interval. The start and end times of the saturation time interval are the compensation light signal P emitted by the second light source 4. c The start and stop times. Figure 5 A schematic diagram showing a saturation time interval determined in an example is shown.

[0054] In addition, the saturation degree of the test value curve after numerical amplification is estimated within the saturation time interval, and then the compensation optical signal P is determined according to the saturation degree within the saturation time interval. c , the higher the saturation degree is, the more compensatory the optical signal P is. c The higher the power.

[0055] In another embodiment, the degree to which the numerically amplified test value curve exceeds the numerical upper limit MAX is used as the saturation level. The greater the excess of the numerical upper limit MAX, the higher the saturation level. Therefore, the difference between the test value of the numerically amplified test value curve within the saturation time interval and the numerical upper limit MAX is calculated to obtain the difference value curve within the saturation time interval. The larger the difference value, the higher the saturation level.

[0056] After obtaining the difference value curve in the saturation time interval, one approach is to convert the difference value curve in the saturation time interval according to the analog-to-digital conversion logic of the analog-to-digital converter to obtain the current time curve, that is, the time variation curve i2(t) of the photocurrent in the saturation time interval. Then, according to P c (t) = i2(t) / η to obtain the compensation optical signal P in the saturation time interval c Time variation curve P c(t). The compensated optical signal P obtained in the above situation c In the saturation time interval, the dynamic curve changes with time, which will lead to higher control complexity. Therefore, in order to simplify the control, another approach is to convert the maximum value of the difference value curve in the saturation time interval according to the analog-to-digital conversion logic of the analog-to-digital converter to obtain the maximum value i of the photocurrent i2(t) in the saturation time interval. 2_max , and follow P c =i 2_max / η conversion to obtain the compensation optical signal P in the saturation time interval c In this case, the compensated optical signal P c In the saturation time interval, it is a constant value and forms a pulse signal. Figure 4 Taking this as an example, this method can simplify the control. Wherein, η is the conversion coefficient of the light signal sent by the second light source and received by the second detector to obtain the photocurrent, which can be obtained through calibration.

[0057] The compensation optical signal P in the saturation time interval can be determined by the above method. c , the actual determined saturation time interval is one or more. When there are multiple saturation time intervals, the controller controls the second driver to drive the second light source to emit the compensation optical signal P in multiple saturation time intervals during an OTDR curve detection process of the optical fiber to be tested. c , for example Figure 4 In the example, please combine Figure 4 As can be seen from (c) in the example, two saturation time intervals are determined. On this basis, the duration of any two saturation time intervals is equal or unequal. The compensation light signal P emitted by the second light source in any two saturation time intervals is equal to or unequal to the duration of any two saturation time intervals. c The signal powers are equal or unequal.

[0058] This application also discloses an optical time domain reflection detection system that avoids event blind zones. Please refer to Figure 6 , the optical time domain reflectometry detection system comprises:

[0059] The first control module is used to drive the first light source to emit a detection light signal P t The optical signal is injected into the optical fiber to be tested, and the first detector detects the optical signal returned by the optical fiber to be tested to generate a photocurrent i1(t).

[0060] The second controller module is used to control the second driver to drive the second light source to emit the compensation light signal P within a predetermined saturation time interval. c The second detector connected in series with the first detector detects the light signal emitted by the second light source to generate a photocurrent i2(t) to offset and compensate the photocurrent i1(t) detected by the first detector, and then generates a current less than the saturation threshold i of the amplifier circuit.th The detection current I(t) is input into the amplifier circuit and analog-to-digital converter in sequence, where t represents time.

[0061] The curve output module is used to obtain the OTDR curve of the optical fiber to be tested according to the output curve of the analog-to-digital converter.

[0062] Each module in the above-mentioned optical time domain reflectometry detection system can be implemented in whole or in part through software, hardware, or a combination thereof. Each of the above-mentioned modules can be embedded in or independent of the processor in the computer device in the form of hardware, or can be stored in the memory of the computer device in the form of software, so that the processor can call and execute the corresponding operations of each of the above modules. Each of the above-mentioned modules is also used to perform the steps of optical time domain reflectometry detection in each embodiment of the present application, and this embodiment will not be described in detail. It can be understood by those skilled in the art that Figure 6 The structure shown in the figure is only a block diagram of a part of the structure related to the solution of the present application, and does not constitute a limitation on the computer device to which the solution of the present application is applied. The specific computer device may include more or fewer components than shown in the figure, or combine certain components, or have a different component arrangement.

[0063] The above description is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and variations directly derived or imagined by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the scope of protection of the present application.

Claims

1. An optical time domain reflectometry detection method for avoiding event blind zones, characterized in that: The optical time domain reflectometry detection method comprises: Drive the first light source to emit a detection light signal P t The optical signal is injected into the optical fiber to be tested, and the first detector detects the optical signal returned by the optical fiber to be tested to generate a photocurrent i1(t); The second light source is driven to emit a compensation light signal P within a predetermined saturation time interval. c The second detector connected in series with the first detector detects the light signal emitted by the second light source to generate a photocurrent i2(t) to offset and compensate the photocurrent i1(t) detected by the first detector, and then generates a current less than the saturation threshold i of the amplifier circuit. th The detection current I(t) is input into the amplifier circuit and analog-to-digital converter in sequence, where t represents time; The OTDR curve of the optical fiber to be tested is obtained according to the output curve of the analog-to-digital converter.

2. The optical time domain reflectometry detection method according to claim 1, wherein: The optical time domain reflectometry detection method further includes: Drive the first light source to emit a test light signal P b Inject the optical fiber to be tested and obtain the test value curve output by the analog-to-digital converter to test the optical signal P b The power of the detection light signal P is much smaller than t The power is to ensure that the photocurrent i detected by the first detector is b (t)<i th ; According to the test optical signal P b The test value curve obtained under the saturation time interval and the compensation optical signal P are estimated c .

3. The optical time domain reflectometry detection method according to claim 2, wherein: According to the test optical signal P b The test value curve obtained under the saturation time interval and the compensation optical signal P are estimated c include: Determine the test optical signal P b The power of the detection light signal P t The power reduction ratio K=P t / P b , according to the number of bits n of the analog-to-digital converter used, determine the upper limit of the value of the analog-to-digital converter output MAX=2 n -1; According to the scaling ratio K, the test optical signal P b The test value curve obtained under the numerical amplification is numerically amplified, and the saturation time interval and the compensation optical signal P are estimated based on the numerical relationship between the test value curve after numerical amplification and the numerical upper limit MAX. c .

4. The optical time domain reflectometry detection method according to claim 3, wherein: Estimate the saturation time interval and compensated optical signal P according to the numerical relationship between the test value curve after numerical amplification and the numerical upper limit MAX c include: Determine the time interval in which the numerical value curve after numerical amplification exceeds the numerical upper limit MAX as the saturation time interval, and estimate the saturation degree of the numerical value curve after numerical amplification within the saturation time interval, and determine the compensation optical signal P according to the saturation degree within the saturation time interval. c The higher the saturation level, the more compensatory the optical signal P c The higher the power.

5. The optical time domain reflectometry detection method according to claim 4, wherein: The estimated saturation degree of the test value curve after numerical amplification within the saturation time interval includes: The difference between the test value of the test value curve after numerical amplification in the saturation time interval and the upper limit MAX is calculated to obtain the difference value curve in the saturation time interval. The larger the difference value, the higher the degree of saturation.

6. The optical time domain reflectometry detection method according to claim 5, wherein: Determine the compensation optical signal P according to the saturation degree within the saturation time interval c include: According to the analog-to-digital conversion logic of the analog-to-digital converter, the difference value curve in the saturation time interval is converted to obtain the photocurrent i2(t) in the saturation time interval, and according to P c (t) = i2(t) / η to obtain the compensation optical signal P in the saturation time interval c Time transformation curve P c (t); Alternatively, the maximum value of the difference value curve within the saturation time interval is converted according to the analog-to-digital conversion logic of the analog-to-digital converter to obtain the maximum value i of the photocurrent i2(t) within the saturation time interval. 2_max , and follow P c =i 2_max / η conversion to obtain the compensation optical signal P in the saturation time interval c ; Wherein, η is the conversion coefficient of the light signal sent by the second light source to be received by the second detector and converted into a photocurrent.

7. The optical time domain reflectometry detection method according to claim 1, wherein: The OTDR curve of the optical fiber under test obtained according to the output of the analog-to-digital converter includes: The compensation curve in the saturation time interval is superimposed on the output curve of the analog-to-digital converter to obtain the OTDR curve of the optical fiber to be tested. The compensation curve in the saturation time interval is the compensation optical signal P detected by the second detector in the saturation time interval according to the analog-to-digital conversion logic of the analog-to-digital converter. c The obtained curve is converted from the photocurrent i2(t).

8. The optical time domain reflectometry detection method according to claim 1, wherein: During an OTDR curve detection process of the optical fiber to be tested, the second light source is driven to emit a compensation optical signal P in multiple saturation time intervals. c The duration of any two saturation time intervals is equal or unequal; the compensation light signal P emitted by the second light source in any two saturation time intervals is equal or unequal; c The signal powers are equal or unequal.

9. An optical time domain reflectometry detection system for avoiding event blind zones, characterized in that: The optical time domain reflectometry detection system comprises: The first control module is used to drive the first light source to emit a detection light signal P t The optical signal is injected into the optical fiber to be tested, and the first detector detects the optical signal returned by the optical fiber to be tested to generate a photocurrent i1(t); The second controller module is used to control the second driver to drive the second light source to emit the compensation light signal P within a predetermined saturation time interval. c The second detector connected in series with the first detector detects the light signal emitted by the second light source to generate a photocurrent i2(t) to offset and compensate the photocurrent i1(t) detected by the first detector, and then generates a current less than the saturation threshold i of the amplifier circuit. th The detection current I(t) is input into the amplifier circuit and analog-to-digital converter in sequence, where t represents time; The curve output module is used to obtain the OTDR curve of the optical fiber to be tested according to the output curve of the analog-to-digital converter.

10. An OTDR device for avoiding event blind zones, characterized in that: The OTDR device includes a controller, a first driver, a first light source, a second driver, a second light source, a first detector, a second detector, an amplifier circuit, and an analog-to-digital converter. The controller is connected to and controls the first driver and the second driver, the first driver is connected to and drives the first light source, and the second driver is connected to and drives the second light source. The first detector and the second detector are connected in series, and the common ends of the first detector and the second detector are connected to the amplifier circuit and the analog-to-digital converter in sequence and then connected to the controller. The first light source transmits an optical signal to the optical fiber to be tested, and the first detector detects the optical signal returned by the optical fiber to be tested; the second detector detects the optical signal emitted by the second light source. The controller is used to perform the steps of the optical time domain reflectometry detection method according to any one of claims 1 to 8.

Images