CN110855351B

CN110855351B - Linearity correcting method for analog photoelectric transmission system

Info

Publication number: CN110855351B
Application number: CN201911141174.9A
Authority: CN
Inventors: 王玮; 王鹏玮
Original assignee: Shandong University of Technology
Current assignee: Shandong University of Technology
Priority date: 2019-11-20
Filing date: 2019-11-20
Publication date: 2022-06-10
Anticipated expiration: 2039-11-20
Also published as: CN110855351A

Abstract

A linearity correction method for an analog photoelectric transmission system belongs to the technical field of electrical measurement. The method is characterized in that: the method comprises the following correction steps: 1001, establishing a nonlinear basic data table; step 1002, sampling the mixed signal to obtain discrete points; step 1003, decomposing the discrete points to obtain direct current parameters; step 1004, calculating a linear transmission coefficient at the current temperature; step 1005, performing data conversion; and 1006 to 1008, finding out discrete points which do not meet the linear relation for compensation, and combining all the discrete points which meet the linear relation to obtain a mixed signal of the transmission system which meets the linear requirement. According to the linearity correction method for the analog photoelectric transmission system, signals transmitted through the nonlinear area of the analog photoelectric transmission system are compensated aiming at the nonlinear defect of the analog photoelectric transmission system, and the measurement precision of the analog photoelectric transmission system is improved.

Description

Linearity correcting method for analog photoelectric transmission system

Technical Field

A linearity correction method for an analog photoelectric transmission system belongs to the technical field of electrical measurement.

Background

In the field of electrical measurement, the physical quantities to be measured are mostly the current and voltage quantities positioned on a high-voltage side, and in order to realize electrical isolation of a high-voltage end and a low-voltage end and improve the anti-interference capability of the transmission of signals to be measured in a strong electromagnetic environment, optical fibers are mostly used for transmitting the signals in engineering. As shown in fig. 3, a conventional analog photoelectric transmission system is configured such that an electrical signal to be transmitted is converted into an optical signal at a transmitting end through electrical/optical conversion, and the electrical signal to be transmitted is obtained at a receiving end through optical/electrical conversion after being transmitted through an optical fiber; the second mode is to transmit the physical electrical signal to be measured to the low-voltage side in the mode of simulating the optical signal by using the optical intensity modulation mode, and the optical intensity modulation mode can keep the complete waveform information to be measured without sampling by using an A/D system on the high-voltage side, so the frequency band of the transmittable signal is far wider than that of the digital transmission mode, and the analog photoelectric transmission system can be applied to small current measurement application, traveling wave measurement application, impulse voltage/current measurement application and the like which have wider frequency band requirements, which cannot be compared with the digital transmission system. Because the sampling link of the high-voltage side A/D system is avoided, the power consumption of the high-voltage side circuit is greatly reduced, and the problem of energy extraction of the high-voltage side for the A/D system is solved. However, the light intensity modulation method has the following problems: to ensure high transmission precision when signals are transmitted in this way, an electric/optical and optical/electric transmission system with high linearity must be established, i.e. the linearity of optical path transmission largely determines the precision of system measurement.

In the prior art, one method for solving the problem of relatively mature linearity of an analog photoelectric transmission system is as follows: the method comprises the steps of generating a known reference signal (generally a direct current signal) at a transmitting end, mixing the reference signal and an electric signal to be transmitted and then transmitting the mixed signal, separating the transmitted reference signal from the electric signal to be transmitted at a receiving end, representing the attenuation degree of the electric signal to be transmitted by using the attenuation degree of the reference signal before and after transmission because the reference signal is a known quantity, and restoring the signal to be transmitted at the transmitting end after processing (such as amplifying) the electric signal obtained by separating at the receiving end. However, it has been found that the signal processing method has the following drawbacks:

as shown in fig. 4, an input value U of the conventional analog photoelectric transmission system_INVoltage input range (0 to U in the figure)_INMAX) Each input value U_INAll correspond to an output value U_OUTTherefore, a curve of the analog photoelectric transmission system approximate to a straight line can be obtained, however, a plurality of points which do not satisfy the linear relation exist on the whole curve of the analog photoelectric transmission system, such as the input value U of the area A in the figure_IN-Error1～U_IN-Error5。

In the actual transmission process, the electrical signal to be transmitted is mixed with the reference signal (see curves La, Lb in fig. 5, respectively) and after transmission by the analog photoelectric transmission system, an attenuated reference signal and an attenuated signal to be transmitted (see curves La ', Lb' in fig. 6, respectively) are obtained. As can be seen from the above description, since there are points (or/and regions) that do not satisfy the linear relationship, if the input values of the electrical signal to be transmitted include points that do not satisfy the linear relationship, the output signal also includes data transmitted through the nonlinear transmission point (for example, region B in fig. 6), therefore, in the prior art, the method for representing the attenuation degree of the original signal to be transmitted by using the attenuation degree of the reference signal only restores (amplifies) the whole signal to be transmitted from the perspective of the attenuation degree of the signal, but does not consider that the nonlinear defect of the analog optical-electrical transmission system itself exists, and the point (or/and region) that does not satisfy the linear relationship actually exists in the signal to be transmitted that is finally restored in the transmission process, so that the transmission accuracy that is finally obtained is reduced.

Disclosure of Invention

The technical problem to be solved by the invention is as follows: the linearity correction method for the analog photoelectric transmission system overcomes the defects of the prior art, compensates signals transmitted through a nonlinear area of the analog photoelectric transmission system aiming at the nonlinear defect of the analog photoelectric transmission system, and improves the measurement precision of the analog photoelectric transmission system.

The technical scheme adopted by the invention for solving the technical problems is as follows: the linearity correction method for the analog photoelectric transmission system comprises the steps that the analog photoelectric transmission system comprises a transmitting end and a receiving end which are connected through optical fibers, and a reference signal U is formed at the transmitting end_{DC reference}Reference signal U_{DC reference}With the electric signal U to be transmitted_ACMixed signal U is obtained after mixing_{IN mixing}Mixed signal U_{IN mixing}Sending the signal to a receiving end by a transmitting end, and obtaining the attenuated mixed signal U at the receiving end_{OUT mixing}The method is characterized in that: for the attenuated mixed signal U_{OUT mixing}The linearity of (2) comprises the following correction steps:

1001, establishing a nonlinear basic data table of the analog photoelectric transmission system at room temperature, and obtaining a linear transmission coefficient of the analog photoelectric transmission system at room temperature;

Step 1002, obtaining a mixed signal U at a receiving end of the analog photoelectric transmission system_{OUT mixing}Then, for the mixed signal U_{OUT mixing}AD sampling is carried out to obtain a signal U_{OUT mixing}The respective discrete points of (a);

step 1003, mixing signal U_{OUT hybrid}Is decomposed, and the attenuated reference signal U 'is calculated for each discrete point'_{DC reference}；

Step 1004, calculating to obtain a linear transmission coefficient of the analog photoelectric transmission system at the current temperature;

step 1005, mixing the signal U under the current temperature_{OUT mixing}Converting the data of all discrete points into corresponding data U at room temperature_{OUT Mixed-Room temperature}；

Step 1006, mix signal U at the current temperature_{OUT mixing}All discrete points are converted into corresponding data U at room temperature_{OUT Mixed-Room temperature}Then, all the U's are judged according to the nonlinear basic data table lookup table_{OUT Mixed-Room temperature}Whether the signal is located in a non-linear region of the analog optical transmission system, if so, executing step 1007, and if not, executing step 1008;

step 1007, mixing signal U under current temperature_{OUT hybrid}Compensating all discrete points which do not meet the linear relation;

at step 1008, all the U's that do not meet the linearity requirement_{OUT mixing}After the discrete points are compensated, all the U meeting the linearity requirement are combined_{OUT mixing}Discrete point to obtain mixed signal U of transmission system meeting linearity requirement_{OUT mixing}。

Preferably, the process for establishing the non-linear basic data table includes the following steps:

1001-1, inputting a plurality of test point input voltages U with different sizes at a fixed voltage interval in a voltage input range of the analog photoelectric transmission system at room temperature_{IN direct current}Correspondingly obtaining a test value U of the output voltage of the test point after the transmission of the analog photoelectric transmission system_{OUT direct current}Further obtaining (U) of each test point_{IN direct current}，U_{OUT direct current}) Point, after testing all test points, obtaining several groups of data sets (U) related to input-output_{IN direct current 1}，U_{OUT DC 1})、(U_{IN DC 2}，U_{OUT DC 2})、……、(U_{IN direct current N}，U_{OUT direct current N})；

Step 1001-2, performing linear fitting on the transmission relationship of the analog optical-electrical transmission system by using the input-output data set obtained in step 1001-1 to obtain a transmission relationship expression of the transmission system: u shape _{OUT direct current}＝K_{At room temperature}*U_{IN direct current}，K_{At room temperature}Simulating the linear transmission coefficient of the photoelectric transmission system at room temperature;

step 1001-3, according to the transmission relational expression obtained in step 1001-2: u shape_{OUT direct current}＝K_{At room temperature}*U_{IN direct current}Inputting the voltage U to each test point in the step 1001-1_{IN direct current}Substituting one by one to calculate the ideal value U of the output voltage of the corresponding test point_{OUT ideal}；

1001-4, finding out all test points which do not satisfy the linear relation;

step 1001-5, outputting two voltage values corresponding to all test points which do not satisfy the linear relation: test value U of test point output voltage_{OUT direct current}And the ideal value U of the output voltage of the test point_{OUT ideal}Composed data set (U)_{OUT direct current}，U_{OUT ideal}) As a non-linear basic data table for an analog optical transmission system.

Preferably, in the step 1001-2, when the transmission relationship of the analog optical-electrical transmission system is linearly fit, the principle of the fit is: the straight line obtained by fitting comprises as many test points as possible.

Preferably, in the step 1001-4, the method for finding out all test points which do not satisfy the linear relationship is: comparing the input voltage U of each test point one by one _{IN direct current}Test value U of corresponding output voltage_{OUT direct current}And an ideal value U_{OUT ideal}And setting an error epsilon to satisfy an inequality | U_{OUT direct current}-U_{OUT ideal}The test points with the value of | larger than epsilon are the test points which do not satisfy the linear relation.

Preferably, in the step 1004, the current temperatureLinear transmission coefficient K of lower analog photoelectric transmission system_{Current temperature}The calculation formula of (2) is as follows:

K_{current temperature}＝U’_{DC reference}/U_{DC reference}

Wherein: u shape_{DC reference}Is a reference signal, U ', formed at the emitter end at the current temperature'_{DC reference}Obtaining the attenuated reference signal at the receiving end at the current temperature, i.e. the reference signal U at the current temperature_{DC reference}It is necessary to select the data in the linear region of the analog optical transmission system according to the nonlinear basic data table of the analog optical transmission system.

Preferably, in step 1005, the signal U is mixed at the current temperature_{OUT mixing}Converting the data of all discrete points into corresponding data U at room temperature_{OUT Mixed-Room temperature}The conversion formula of (1) is as follows:

wherein: k_{Current temperature}Simulating the linear transmission coefficient, K, of an optical transmission system for the current temperature_{At room temperature}The linear transmission coefficient of the optical-electrical transmission system is simulated at room temperature.

Preferably, in step 1007, the mixed signal U is added_{OUT mixing}The method for compensating all the discrete points which do not satisfy the linear relation comprises the following steps: for mixed signals U according to non-linear basic data tables_{OUT mixing}Looking up the discrete points not meeting the linear relation to judge whether the non-linear basic data table has the mixed signal U_{OUT mixing}U with same value corresponding to discrete points_{OUT Mixed-Room temperature}If present, the mixed signal U is recorded_{OUT mixing}Discrete point replacement by U_{OUT MIXED-ROOM TEMPERATURE}Corresponding U_{OUT ideal}(ii) a If there is no mixing signal U in the non-linear basic data table_{OUT mixing}U with same value corresponding to discrete points_{OUT Mixed-Room temperature}Using and mixing the signal U_{OUT mixing}U with same value corresponding to discrete points_{OUT Mixed-Room temperature}Obtaining a theoretical correction value U of the two closest points by utilizing an interpolation method_{OUT ideal}And for the mixed signal U_{OUT mixing}Discrete points are replaced.

Compared with the prior art, the invention has the beneficial effects that:

1. according to the linearity correction method for the analog photoelectric transmission system, signals transmitted through the nonlinear area are compensated aiming at the nonlinear defect of the analog photoelectric transmission system, and the measurement accuracy of the analog photoelectric transmission system is improved.

2. In the linearity correction method for the analog photoelectric transmission system, aiming at the problem that the linear analog photoelectric system has a nonlinear transmission area, a data point corresponding to the nonlinear transmission area is found by pretesting the transmission characteristic of the optical path system, and a reference basis and correction data are provided for judging the nonlinear data point when the system runs by establishing a basic data table. And finally, the measurement precision of the analog photoelectric transmission system is improved.

3. In the linearity correction method for the analog optical-electrical transmission system, the nonlinear data table is obtained at a specific temperature (room temperature), but the data table and the method are not limited by the temperature during operation. The data can be judged and corrected by converting the sampled data into corresponding data at room temperature.

4. When the linearity correction method for the analog photoelectric transmission system is applied, the influence of introducing extra optical fiber coupling and optical fiber attenuation is avoided.

5. The linearity correction method for the analog photoelectric transmission system can be used for the precision correction of any analog photoelectric transmission system with an obvious nonlinear transmission area.

Drawings

Fig. 1 is a flowchart of a linearity correction method for an analog optical-electrical transmission system.

Fig. 2 is a flow chart for establishing a non-linear basic data table of a linearity correction method for an analog optical-electrical transmission system.

Fig. 3 is a schematic block diagram of a prior art analog optical-to-electrical transmission system.

Fig. 4 is a graph of input-output curves of a prior art analog optical-to-electrical transmission system.

Fig. 5 is a graph of mixed signals at the transmitting end of an analog optical-electrical transmission system in the prior art.

Fig. 6 is a graph of a mixed signal at a receiving end of an analog optical-electrical transmission system in the prior art.

Detailed Description

FIGS. 1-2 illustrate preferred embodiments of the present invention, and the present invention will be further described with reference to FIGS. 1-2.

In the linearity correction method for an analog optical-electrical transmission system of the present application, the transmission method of the analog optical-electrical transmission system (hereinafter referred to as a transmission system) itself is: a known reference signal (generally a dc signal, denoted signal U) is generated at the transmitting end of the transmission system_{DC reference}) And transmitting the signal U at the transmitting end_{DC reference}With the electrical signal to be transmitted (denoted as signal U)_AC) Mixed to generate a mixed signal U to be transmitted_{IN mixing}Mixed signal U_{IN mixing}After being transmitted to a receiving end through an analog photoelectric transmission system, a mixed signal U is obtained_{OUT mixing}Due to mixing of the signal U after transmission_{OUT mixing}With respect to the mixed signal U_{IN mixing}There will be some attenuation and therefore mixing of the signal U at the receiving end_{OUT mixing}Decomposed to obtain an attenuated reference signal (denoted as signal U'_{DC reference}) And the attenuated signal to be transmitted: signal U'_AC。

Due to signal U_{DC reference}Sum signal U_ACWith the same degree of attenuation during transmission, thus making use of the signal U_{DC reference}Signal U characterised by the degree of attenuation before and after transmission_ACTo pass the signal U'_{DC reference}Relative to signal U_{DC reference}Degree of attenuation of to signal U'_ACAmplifying to restore a signal U_AC。

As shown in fig. 1, a linearity correction method for an analog optical-electrical transmission system includes the following steps:

1001, establishing a nonlinear basic data table for simulating an optical-electrical transmission system at room temperature;

the method specifically comprises the following steps as shown in figure 2:

1001-1, measuring at room temperature to obtain a plurality of groups of input-output data sets of the analog photoelectric transmission system;

at room temperature, in the complete voltage input range of the analog optical-electrical transmission system, a plurality of test point input voltages with different sizes are input at certain voltage intervals (such as 20 mV): u shape _{IN direct current}And obtaining test values of the output voltages of the test points corresponding to the test points: u shape_{OUT direct current}Thereby obtaining a plurality of (U)_{IN direct current}，U_{OUT direct current}) Point, thereby obtaining sets of data sets (U) about input-output_{IN direct current 1}，U_{OUT DC 1})、(U_{IN DC 2}，U_{OUT DC 2})、……、(U_{IN direct current N}，U_{OUT direct current N}). Each U_{IN direct current}The smaller the interval between the two, the higher the correction resolution of the nonlinear data in the system transmission, and thus the higher the final transmission precision of the system.

Step 1001-2, performing linear fitting on the analog photoelectric transmission system;

using the sets of data sets (U) obtained in step 1001-1_{IN direct current}，U_{OUT direct current}) And performing linear fitting on the transmission relationship of the transmission system to obtain a transmission relationship expression of the transmission system: u shape_{OUT direct current}＝K_{At room temperature}*U_{IN direct current}，K_{At room temperature}The linear transmission coefficient of the photoelectric transmission system at room temperature is simulated. The principle of the fitting is that the straight line obtained by fitting comprises as many test points as possible, so that the correction workload of the nonlinear data can be reduced to the maximum extent.

1001-3, calculating an ideal value of an output value in a data set of the analog photoelectric transmission system;

according to the transmission relational expression obtained in step 1001-2: u shape _{OUT direct current}＝K_{At room temperature}*U_{IN direct current}Substituting the input voltage of each test point in the step 1001-1 into the input voltage of each test point one by one: u shape_{IN direct current}And calculating the ideal value of the output voltage of the corresponding test point: u shape_{OUT ideal}。

1001-4, finding out all test points which do not satisfy the linear relation;

comparing the input voltage U of each test point one by one_{IN direct current}Test value U of corresponding output voltage_{OUT direct current}And an ideal value U_{OUT ideal}And setting an error epsilon to satisfy an inequality | U_{OUT direct current}-U_{OUT ideal}The test points with the value of | larger than epsilon are the test points which do not satisfy the linear relation.

1001-5, obtaining a nonlinear basic data table for simulating the photoelectric transmission system at room temperature;

finding and recording each linearity failure point U_{OUT direct current}Corresponding theoretical ideal signal U_{OUT ideal}And as a set of non-linear fundamental data (U)_{OUT direct current}，U_{OUT ideal}) All of (U)_{OUT direct current}，U_{OUT ideal}) I.e. constitutes a non-linear basic data table of the transmission system. Since these points are measured at room temperature, it is noted as (U)_{OUT DC-ROOM TEMPERATURE}，U_{OUT ideal})。

Step 1002, sampling an output signal of an analog optical transmission system;

outputting a signal (mixed signal U) at the receiving end of a transmission system _{OUT hybrid}) Then, for the mixed signal U_{OUT mixing}AD sampling is carried out to obtain a signal U_{OUT hybrid}Each discrete point of (a);

step 1003, obtaining a reference signal in an output signal of the analog photoelectric transmission system;

calculating a mixed signal U using an FFT algorithm_{OUT mixing}The DC-amount (attenuated reference signal) U' DC-reference in each discrete point.

Step 1004, calculating a linear transmission coefficient of the analog photoelectric transmission system at the current temperature;

since the non-linear basic data of the transmission system is obtained through the step 1001Table, whereby the reference signal U is selected before signal transmission by the transmission system_{DC reference}It is necessary to select in the linear region of the transmission system, so that the reference signal U_{DC reference}And a reference signal U_{DC reference}Obtaining an attenuated reference signal U 'after transmission by a transmission system'_{DC reference}Corresponding data (U)_{DC reference}，U’_{DC reference}) Located in the linear region of the transmission system.

Due to (U)_{DC reference}，U’_{DC reference}) The point is located in the linear region of the transmission relationship, so that (U) is the temperature of the system, no matter what temperature it is_{DC reference}，U’_{DC reference}) Still within the linear transmission region at the current temperature and therefore directly according to (U) _{DC reference}，U’_{DC reference}) Calculating the linear transmission coefficient K of the transmission system at the current temperature_{Current temperature}I.e. K_{Current temperature}＝U’_{DC reference}/U_{DC reference}。

Step 1005, converting the signal output by the analog photoelectric transmission system at the current temperature into a numerical value at room temperature;

the ratio of the ideal linear transmission coefficient of the transmission system at room temperature to the ideal linear transmission coefficient at the temperature is alpha, namely;

when the current temperature is not room temperature (K)_{Current temperature}≠K_{At room temperature}) U at the current temperature can be calculated by calculating the change times of the two_{OUT mixing}Converting the data of all discrete points into corresponding data U at room temperature_{OUT Mixed-Room temperature}Namely:

step 1006, judging whether the output signal of the analog optical-electrical transmission system is in a linear region at the current temperature;

all U at the current temperature_{OUT mixing}Conversion to data U at room temperature_{OUT Mixed-Room temperature}Then, all the U's are judged according to the nonlinear basic data table lookup table_{OUT Mixed-Room temperature}If the transmission system is located in the non-linear region of the transmission system, step 1007 is executed, and if the transmission system is located outside the non-linear region of the transmission system, step 1008 is executed.

In the nonlinear basic data table (U) _{OUT DC-ROOM TEMPERATURE}，U_{OUT ideal}) In the table look-up process, each U is a linear system similar to an ideal one because the analog photoelectric system_{OUT direct current}The point is certainly along with U_{IN direct current}The point increases linearly or approximately linearly, so that even if the nonlinear transmission points are larger/smaller than the curve of the ideal linear relation, the non-ideal U_{OUT direct current}The size interval occupied by the points is also constant, i.e. the deviation of the points does not cause them to have the same U as some points on the linear relationship curve_{OUT direct current}And the ordinate, so that the situation of misjudgment can not occur. So by looking at U_{OUT Mixed-Room temperature}Whether the size of (1) corresponds to U in a non-linear interval or not_{OUT direct current}The judgment can be simply finished within the range of the ordinate.

Step 1007, compensating the output signal which does not satisfy the linear relation under the current temperature;

in pairs of U not satisfying the linear relationship_{OUT mixing}Corresponding U_{OUT Mixed-Room temperature}When compensation is performed, if there are U with the same value in the non-linear basic data table_{OUT Mixed-Room temperature}Replacing itself with the corresponding U_{OUT ideal}(ii) a If there is no U with the same value in the non-linear basic data table _{OUT MIXED-ROOM TEMPERATURE}Can use the method of interpolation of two points closest to it to obtain its theoretical correction value U_{OUT ideal}。

Step 1008, obtaining an output signal meeting the linearity requirement;

obtaining all U meeting the linearity requirement_{OUT mixing}And all the U's that do not meet the linearity requirement_{OUT mixing}After the discrete point completes compensation, the output signal of the transmission system is obtainedU_{OUT mixing}All discrete points satisfying the linear relationship.

The foregoing is directed to preferred embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. However, any simple modification, equivalent change and modification of the above embodiments according to the technical essence of the present invention are within the protection scope of the technical solution of the present invention.

Claims

1. A linearity correction method for analog photoelectric transmission system includes connecting emitting end and receiving end by optical fiber, forming reference signal U at emitting end _{DC reference}Reference signal U_{DC reference}With the electric signal U to be transmitted_ACMixed signal U is obtained after mixing_{IN mixing}Mixed signal U_{IN mixing}Sending the signal to a receiving end by a transmitting end, and obtaining the attenuated mixed signal U at the receiving end_{OUT mixing}The method is characterized in that: for the attenuated mixed signal U_{OUT mixing}The linearity of (2) comprises the following correction steps:

step 1002, obtaining a mixed signal U at a receiving end of the analog photoelectric transmission system_{OUT mixing}Then, for the mixed signal U_{OUT mixing}AD sampling is carried out to obtain a signal U_{OUT mixing}Each discrete point of (a);

step 1003, mixing signal U_{OUT mixing}Is decomposed, and the attenuated reference signal U 'is calculated for each discrete point'_{DC reference}；

step 1005, mixing the signal U under the current temperature_{OUT mixing}All ofConverting the data of the discrete points into corresponding data U at room temperature_{OUT Mixed-Room temperature}；

Step 1006, mixing the current temperature down-mixing signal U_{OUT mixing}All discrete points are converted into corresponding data U at room temperature_{OUT Mixed-Room temperature}Then, all the U's are judged according to the nonlinear basic data table lookup table_{OUT Mixed-Room temperature}Whether the signal is located in a non-linear region of the analog optical transmission system, if so, executing step 1007, and if not, executing step 1008;

step 1007, mixing signal U under current temperature_{OUT mixing}Compensating all discrete points which do not meet the linear relation;

at step 1008, all the U's that do not meet the linearity requirement_{OUT mixing}After the discrete points are compensated, all the U meeting the linearity requirement are combined_{OUT mixing}Discrete point to obtain mixed signal U of transmission system meeting linearity requirement_{OUT mixing}；

The establishing process of the nonlinear basic data table comprises the following steps:

1001-1, inputting a plurality of test point input voltages U with different sizes at a fixed voltage interval in a voltage input range of the analog photoelectric transmission system at room temperature_{IN direct current}Correspondingly obtaining a test value U of the output voltage of the test point after the transmission of the analog photoelectric transmission system _{OUT direct current}Further obtaining (U) of each test point_{IN direct current}，U_{OUT direct current}) Point, after testing all test points, obtaining several groups of data sets (U) related to input-output_{IN direct current 1}，U_{OUT DC 1})、(U_{IN DC 2}，U_{OUT DC 2})、……、(U_{IN direct current N}，U_{OUT direct current N})；

Step 1001-2, performing linear fitting on the transmission relationship of the analog optical-electrical transmission system by using the input-output data set obtained in step 1001-1 to obtain a transmission relationship expression of the transmission system: u shape_{OUT direct current}＝K_{At room temperature}*U_{IN direct current}，K_{At room temperature}Simulating the linear transmission coefficient of the photoelectric transmission system at room temperature;

1001-4, finding out all test points which do not satisfy the linear relation;

step 1001-5, outputting two voltage values corresponding to all test points which do not satisfy the linear relation: test value U of test point output voltage_{OUT direct current}And the ideal value U of the output voltage of the test point_{OUT ideal}Composed data set (U)_{OUT direct current}，U_{OUT ideal}) As a nonlinear basic data table of an analog photoelectric transmission system;

in the step 1001-2, when the transmission relationship of the analog optical-electrical transmission system is linearly fitted, the fitting principle is as follows: the straight line obtained by fitting comprises as many test points as possible;

in step 1001-4, the method for finding out all test points which do not satisfy the linear relationship is as follows: comparing the input voltage U of each test point one by one_{IN direct current}Test value U of corresponding output voltage_{OUT direct current}And an ideal value U_{OUT ideal}And setting an error epsilon to satisfy an inequality | U_{OUT direct current}-U_{OUT ideal}The test point with the | larger than the epsilon is a test point which does not satisfy the linear relation;

in the step 1004, the linear transmission coefficient K of the analog optical-electrical transmission system at the current temperature_{Current temperature}The calculation formula of (2) is as follows:

K_{current temperature}＝U’_{DC reference}/U_{DC reference}

Wherein: u shape_{DC reference}Is a reference signal, U ', formed at the emitter end at the current temperature'_{DC reference}Obtaining the attenuated reference signal at the receiving end at the current temperature, i.e. the reference signal U at the current temperature_{DC reference}According to the analog lightThe nonlinear basic data table of the electric transmission system is selected in a linear area of the analog photoelectric transmission system;

In step 1007, the mixed signal U is processed_{OUT mixing}The method for compensating all the discrete points which do not satisfy the linear relation comprises the following steps: for mixed signals U according to non-linear basic data tables_{OUT mixing}Looking up the table for the discrete points not meeting the linear relation, and judging whether the signal U exists in the nonlinear basic data table or not_{OUT mixing}U with same value corresponding to discrete points_{OUT Mixed-Room temperature}If present, the mixed signal U_{OUT mixing}Replacement of discrete points with U_{OUT Mixed-Room temperature}Corresponding U_{OUT ideal}(ii) a If there is no mixing signal U in the non-linear basic data table_{OUT mixing}U with same value corresponding to discrete points_{OUT Mixed-Room temperature}Using and mixing the signal U_{OUT mixing}U with same value corresponding to discrete points_{OUT Mixed-Room temperature}Obtaining a theoretical correction value U of the two closest points by utilizing an interpolation method_{OUT ideal}And for the mixed signal U_{OUT mixing}Discrete points are replaced.

2. The linearity correction method for an analog optical-electrical transmission system according to claim 1, characterized in that: in step 1005, the current temperature is down-mixed with the signal U_{OUT mixing}Converting the data of all discrete points into corresponding data U at room temperature _{OUT Mixed-Room temperature}The conversion formula of (1) is as follows: