A method for verifying the received optical power intensity by inverse calculation of common points

Abstract

The present invention discloses a method for checking the received optical power intensity by inverse calculation of common points. The AD value corresponding to each calibrated power point of the RxDDMI of the device under test is first calculated, and the power response relationship obtained in the calibration link is substituted to obtain the reported calculated value of the RxDDMI of each calibrated power point. Finally, during the actual power verification, the device under test DUT performs the calculation of the AD conversion success rate, and then determines whether the deviation between the reported calculated value and the actual power value meets the threshold requirement. The test flow of the present invention is improved in the verification process, and the inverse calculation method is directly used. The main functions of the inverse calculation verification are: verifying the deviation between the fitted power response and the actual power response; there is no need to repeatedly set the Rx power, and the AD value of each calibration point is directly used to calculate the reported power value, and this process is completed by the PC.

Description

Technical Field

[0001] The invention relates to a verification method, in particular to a verification method for common point inverse calculation of received optical power intensity. Background Art

[0002] In many optical service-related devices (including but not limited to optical modules, optical modems, BOBs, etc.), optical power monitoring circuits are designed to monitor the power of input optical signals so as to detect changes in input optical signals in a timely manner. The optical power monitoring circuit generally includes a power detector, an amplifier, and an ADC (analog-to-digital converter). Its working principle is as follows: When the input optical signal enters the power detector (PD), it will generate a current signal that is positively correlated with the input power. After passing through the amplification circuit, it will be converted into a voltage signal, and its signal amplitude is positively correlated with the input power. Finally, the voltage signal is sampled by the analog-to-digital converter (ADC) and converted into the numerical value of the digital signal. In addition to the above hardware circuit, in order to correctly report the optical power, it is also necessary to know the response relationship between the Rx power and the AD value. After the power detection circuit detects the intensity AD value corresponding to the input power, it is necessary to calculate the corresponding RxDDM reporting power according to the power response relationship. This is the working principle and working process of the power monitoring circuit. Figure 1 This is a typical optical power monitoring circuit diagram.

[0003] In summary, RxDDMI cannot directly detect and report the optical power value with hardware circuits, but must be converted through the AD value and the response relationship of Rx optical power. To obtain the optical power response relationship, two steps, calibration and verification, are required in the production process.

[0004] Calibration is to generate the response relationship between the AD value of RxDDMI and the input optical power. In many cases, the least square method is used to fit a straight line (y=ax+b) or a high-order curve (such as a second-order curve y=ax 2 + bx + c). If calibration is not performed, the power monitoring circuit cannot calculate the corresponding Rx optical power according to the parameter table or expression.

[0005] Verification is to check whether the response relationship generated by calibration is consistent with the actual situation.

[0006] Due to test efficiency and cost considerations, the number of power points of the input light in the calibration stage is limited. In addition, due to the influence of random fluctuations in the test system, fiber operation, light source and AD readings, there will definitely be a deviation between the fitted power response relationship and the actual power response. In addition, when the response relationship is calibrated to the device under test, writing errors or failure to write into effect may occur.

[0007] Therefore, after calibration, it is necessary to verify whether the calibrated power response relationship is accurate to determine whether the calibrated power response relationship conforms to the actual situation. Since several different input powers need to be adjusted during calibration, and then the power report corresponding to the received optical power intensity prompt is queried, the external instrument setting and report query require additional test time. Compared with ONT BOB products, the RxDDMI calibration time may account for about 10% of the total BOB commissioning time.

[0008] In order to solve the problem of deviation between the fitted power response relationship and the real power response in the calibration step, as well as the situation of writing errors or failure to write and take effect; in the verification step, the external instrument setting and reporting query test time is long. It is urgent to provide a new verification method to solve the above problems. Summary of the invention

[0009] In order to solve the problems of power response deviation and long verification time in the optical power monitoring circuit, the present invention provides a common point inverse calculation received optical power intensity verification method, which realizes optical power value calculation and verification by adopting virtual calculation instead of real power verification, thereby improving the test efficiency.

[0010] The present invention provides the following technical solutions: A common point inverse calculation received optical power intensity calibration method, firstly calculates the AD value corresponding to each calibrated power point of the RxDDMI of the device under test, substitutes it into the power response relationship obtained in the calibration link, and obtains the RxDDMI reported calculated value of each calibrated power point. Finally, when the actual power is used for calibration, the device under test DUT performs the calculation of the AD conversion success rate, and then judges whether the deviation between the reported calculated value and the actual power value meets the threshold requirement.

[0011] The specific calibration and verification process is as follows: Step 1: Calibration Set the input optical power PA0 and query the related ADC register value AD0 of RxDDMI; Set the input optical power PA1 and query the related ADC register value AD1 of RxDDMI; … Set the input optical power PAn and query the relevant ADC register value ADn of RxDDMI; Step 2: Fitting Substitute (PA0, AD0), (PA1, AD1) ... (PAn, ADn) into the least square method to calculate the slope Slope and intercept Offset of the fitting line; The power response relationship is: P = f(AD) = Slope*AD + Offset, Calibrate Slope and Offset to the device under test; Step 3: According to the AD value of the calibration point, the reported power is obtained by inverse calculation (completed by the virtual calculation PC) Calculate the reported power according to the fitting straight line formula: P = f(AD)= Slope*AD + Offset The AD value of calibration point 0 corresponds to the power reporting value PB0 = Slope*AD0 + Offset; The AD value of calibration point 1 corresponds to the power reporting value PB1 = Slope*AD1 + Offset; … The AD value of calibration point n corresponds to the power reporting value PBn = Slope*ADn + Offset; Step 4: Verification Compare the actual power and reported power deviation at each calibrated power point: Delt0 = |PA0 - PB0|; Delt1 = |PA1 - PB1|; … Deltn = |PAn - PBn|; Determine whether Delt0, Delt1, ... Deltn are less than the deviation threshold allowed by the corresponding product specifications.

[0012] It also includes step 5, parameter writing verification, which is to verify whether the Slope and Offset are successfully calibrated to the device under test: Query the current RxDDMI power reporting value PCn, and determine whether the calculated value PBn is equal to the reported value PCn. If they are equal, it indicates that the previous Slope and Offset parameters have been correctly calibrated to the device under test DUT.

[0013] Determine whether the calculated value PBn is equal to the reported value PCn: A fluctuation threshold is used here to measure whether they are consistent. If the AD fluctuations of multiple samples fall within the threshold, it indicates that the corresponding optical powers are equal.

[0014] Compared with the prior art, the present invention has the following beneficial effects: 1. The test flow of the present invention is improved in the verification process, which directly adopts the inverse calculation method to replace the actual power verification by the common point inverse calculation method, thereby saving test time and instrument occupancy.

[0015] 2. To finally verify that parameters such as Slope and Offset are correctly calibrated to the DUT, the power reported value at the current power point can be compared with the calculated value by inverse calculation to determine whether the above calibration process is written correctly, and the inverse calculation algorithm is consistent with the algorithm on the DUT software. There is no need to repeatedly set the Rx power, and the AD value of each calibration point is directly used to calculate the reported power value. This process can be completed by the virtual computing PC. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a typical optical power monitoring circuit.

[0017] Figure 2 It is a flow chart of the present invention.

[0018] Figure 3 This is the power response diagram of the straight line fitting.

[0019] Figure 4 This is a flowchart of the reverse calculation verification process of the present invention. Implementation The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] Figure 2 , 3 As shown in Figure 4, the present invention provides a method for verifying the received optical power intensity by inverse calculation of common point, which calculates the AD value corresponding to each calibrated power point of the RxDDMI of the device under test, substitutes it into the power response relationship obtained in the calibration link, and obtains the RxDDMI reported calculated value of each calibrated power point. Finally, when the actual power is used for verification, the device under test DUT performs the calculation of the AD conversion success rate, and then determines whether the deviation between the reported calculated value and the actual power value meets the threshold requirement.

[0021] The DUT performs power reporting operation process: The DUT can only query the reported value AD of the power detector PD, but according to the Slope and Offset parameters calibrated to the DUT, the AD to power conversion formula can be obtained: P = f(AD) = Slope*AD + Offset, thereby calculating the power reporting value.

[0022] The specific calibration and verification process is as follows: Step 1: Calibration: Set the input optical power PA0 and query the related ADC register value AD0 of RxDDMI; Set the input optical power PA1 and query the related ADC register value AD1 of RxDDMI; … Set the input optical power PAn and query the relevant ADC register value ADn of RxDDMI; Step 2: Fitting Substitute (PA0, AD0), (PA1, AD1) ... (PAn, ADn) into the least square method to calculate the slope Slope and intercept Offset of the fitting line; The power response relationship is: P = f(AD) = Slope*AD + Offset, Calibrate Slope and Offset to the device under test; Step 3: According to the AD value of the calibration point, the reported power is obtained by inverse calculation (completed by the virtual calculation PC) Calculate the reported power according to the fitting straight line formula: P = f(AD)= Slope*AD + Offset The AD value of calibration point 0 corresponds to the power reporting value PB0 = Slope*AD0 + Offset; The AD value of calibration point 1 corresponds to the power reporting value PB1 = Slope*AD1 + Offset; … The AD value of calibration point n corresponds to the power reporting value PBn = Slope*ADn + Offset; Step 4: Verification Compare the actual power and reported power deviation at each calibrated power point: Delt0 = |PA0 - PB0|; Delt1 = |PA1 - PB1|; … Deltn = |PAn - PBn|; Determine whether Delt0, Delt1, ... Deltn are less than the deviation threshold allowed by the corresponding product specifications.

[0023] Step 5: Parameter writing verification (this step is to verify whether the Slope and Offset are successfully calibrated to the device under test) Query the current RxDDMI power reported value PCn, and determine whether the calculated value PBn is equal to the reported value PCn (because there is always a certain jitter in the input power, the AD value will also have a slight jitter, and the AD values ​​before and after may not be completely equal, but they will be relatively close. Here, a fluctuation threshold value can be used to measure whether they are consistent. If the AD fluctuations of multiple samples fall within the threshold, it indicates that the corresponding optical powers are equal). If they are equal, it indicates that the previous Slope and Offset parameters have been correctly calibrated to the DUT.

[0024] The test flow of the present invention is improved in the verification process. Instead of repeatedly setting the verification point Rx power and then querying the reported power, the inverse calculation method is directly adopted. The main function of the inverse calculation verification is to verify the deviation between the fitted power response and the actual power response.

[0025] The solution before the improvement adopted the method of setting the Rx power and then querying the RxDDMI power report of the device under test. The process of calculating and reporting the power based on the AD value was completed by the device under test. However, the solution after the improvement does not need to repeatedly set the Rx power, and directly uses the AD value of each calibration point to calculate the reported power value. This process is completed by the PC.

[0026] Figure 3 As shown, the horizontal axis represents Rx power and the vertical axis represents AD value.

[0027] The b curve represents the real power response curve, which accurately reflects the actual situation of AD changing with Rx power. The b curve is a theoretical response curve and cannot be accurately obtained in practice.

[0028] Straight line a represents the power response curve obtained by fitting a finite number of calibration points, which approximately characterizes the variation of the AD value with the Rx power.

[0029] like Figure 3 As shown, during calibration, 1. Input 5 different Rx power values ​​PA1 / PA2 / PA3 / PA4 / PA5, and query the corresponding 5 AD reported values ​​AD1 / AD2 / AD3 / AD4 / AD5 of RxDDMI, as shown in the figure, and get 5 calibration points (triangle points). These 5 calibration points fall on the real power response curve (as shown in curve b in the figure).

[0030] 2. In fact, it is impossible to get an accurate power response curve based on these 5 calibration points, but only an approximate power response curve is desired. In most cases, a first-order fitting algorithm is used to fit the slope Slope and intercept Offset parameters of the straight line through 5 calibration points, and a straight line (such as line a in the figure) is obtained to approximately represent the power response relationship P=Slope*AD+Offset; then the Slope and Offset parameters are calibrated to the device under test. Of course, a second-order or even higher-order fitting algorithm is sometimes used. Different products may use different fitting algorithms. This article does not describe the specific fitting algorithm in detail. However, no matter which fitting algorithm is used, it does not affect the effectiveness of the verification method in this article.

[0031] 3. There is a difference between the actual power response curve b and the fitting line a. The 5 calibration points (triangular points) fall on the curve b, and the 5 power reporting points (black points) fall on the fitting line a. There is a difference between them.

[0032] 4. In the current mainstream solution, the Rx power PA1 / PA2 / PA3 / PA4 / PA5 of each calibration point will be repeatedly input. According to the real power response curve b, the RxDDMI of the device under test will detect 5 different AD values ​​AD1 / AD2 / AD3 / AD4 / AD5. Then the device under test calculates the corresponding reported power PB1 / PB2 / PB3 / PB4 / PB5 according to the approximate response relationship represented by the fitting straight line a.

[0033] 5. The method of the present invention directly uses the data of 5 calibration points (PA1, AD1) (PA2, AD2) (PA3, AD3) (PA4, AD4) (PA5, AD5) and the expression of the fitting line P=k*AD+b, and the PC directly calculates the reported power values ​​PB1 / PB2 / PB3 / PB4 / PB5 without actually repeating the steps of setting the input power & querying AD in 4, thereby improving the test efficiency.

[0034] Figure 3 What is shown is the power response diagram of the straight line fitting. The inverse calculation verification method described in this article is also applicable to the power response curve verification using a high-order fitting algorithm.

[0035] The verification method of the present invention only needs virtual calculation on the PC side and comparison with the original power data during calibration. All verification processes can be implemented in the PC program, and the test time consumed can be ignored. The traditional solution needs to set different input powers and then query the RxDDMI power report. It is necessary to set and query the external light source / adjustable optical attenuator / power meter and other devices, as well as the power report query command interaction between the circuit under test.

[0036] Taking the RxDDMI check of the optical modem BOB as an example, the power check consumes 3-7s, which is roughly equivalent to the RxDDMI calibration time, accounting for about 10% of the total test time of the optical modem BOB. The new check method of the present invention can reduce the RxDDMI check time to 0s.

[0037] The present invention aims to provide a verification method, which calculates the AD value corresponding to each calibrated power point of RxDDMI, substitutes it into the power response relationship obtained in the calibration link, obtains the RxDDMI reported calculation value of each calibrated power point (when using actual power verification, the DUT performs the calculation of the AD conversion success rate), and then determines whether the deviation between the reported calculation value and the actual power value meets the threshold requirement.

[0038] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for verifying the received optical power intensity by inverse calculation of common points, characterized in that: First, calculate the AD value corresponding to each calibrated power point of the RxDDMI of the device under test, substitute it into the power response relationship obtained in the calibration link, and inversely calculate the reported RxDDMI calculated value of each calibrated power point. Finally, during the actual power calibration, the device under test DUT performs the calculation of the AD conversion success rate, and then determines whether the deviation between the reported calculated value and the actual power value meets the threshold requirement.

2. The method for verifying the received optical power intensity by inverse calculation of common points according to claim 1, characterized in that: The specific calibration and verification process is as follows: Step 1: Calibration Set the input optical power PA0 and query the related ADC register value AD0 of RxDDMI; Set the input optical power PA1 and query the related ADC register value AD1 of RxDDMI; …… Set the input optical power PAn and query the relevant ADC register value ADn of RxDDMI; Step 2: Fitting Substitute (PA0, AD0), (PA1, AD1) ... (PAn, ADn) into the least square method to calculate the slope Slope and intercept Offset of the fitting line; The power response relationship is: P = f(AD) = Slope*AD + Offset, Calibrate Slope and Offset to the device under test; Step 3: According to the AD value of the calibration point, the reported power is obtained by inverse calculation, which is completed by the virtual calculation PC Calculate the reported power according to the fitting straight line formula: P = f(AD)= Slope*AD + Offset The AD value of calibration point 0 corresponds to the power reporting value PB0 = Slope*AD0 + Offset; The AD value of calibration point 1 corresponds to the power reporting value PB1 = Slope*AD1 + Offset; …… The AD value of calibration point n corresponds to the power reporting value PBn = Slope*ADn + Offset; Step 4: Verification Compare the actual power and reported power deviation at each calibrated power point: Delt0 = |PA0 - PB0|; Delt1 = |PA1 - PB1|; …… Deltn = |PAn - PBn|; Determine whether Delt0, Delt1, ... Deltn are less than the deviation threshold allowed by the corresponding product specifications.

3. The method for verifying the received optical power intensity by inverse calculation of common points according to claim 1, characterized in that: It also includes step 5, parameter writing verification, which is to verify whether the Slope and Offset are successfully calibrated to the device under test: Query the current RxDDMI power reporting value PCn, and determine whether the calculated value PBn is equal to the reported value PCn. If they are equal, it indicates that the previous Slope and Offset parameters have been correctly calibrated to the device under test DUT.

4. The method for verifying the received optical power intensity by inverse calculation of common points according to claim 3, characterized in that: Determine whether the calculated value PBn is equal to the reported value PCn: A fluctuation threshold is used here to measure whether they are consistent. If the AD fluctuations of multiple samples fall within the threshold, it indicates that the corresponding optical powers are equal.

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