A method, device and storage medium for compensating optical fiber measurement data

Abstract

The application provides a fiber measurement data compensation method, device, equipment and storage medium, which can preprocess a first measurement data set of a measured fiber line based on the noise mean value of the first measurement data set to obtain a first measurement data set without noise. Then, a second measurement data set of the measured fiber line is preprocessed based on the noise mean value of the second measurement data set to obtain a second measurement data set without noise. The end position of the measured fiber line is determined based on the second measurement data set without noise. The reference point position of compensation is determined based on the parameters of the measurement signal corresponding to the end position and the distance value of the previous position adjacent to the end position. The compensation model is determined based on the reference point position and the measurement data in the first measurement data set without noise. The measurement signal is compensated based on the model, which can avoid misjudgment and interference.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optical communication technology, and in particular to a fiber measurement data compensation method, device, equipment and storage medium. BACKGROUND

[0002] OTDR (Optical Time Domain Reflectometer) is the most commonly used tool in optical cable line maintenance. The dynamic range of OTDR determines the length of the measurable optical fiber. In actual use, in order to improve the dynamic range of OTDR to meet the testing requirements of long-distance optical fiber, the dynamic range is usually increased by increasing the measurement signal strength, which will increase the detection blind area, that is, the problem of signal tailing. Signal tailing will greatly interfere with the judgment of test results, causing misjudgment. SUMMARY

[0003] In order to solve the problem of OTDR signal tailing interference and misjudgment in the prior art, the present application provides a fiber measurement data compensation method, device, equipment and storage medium, which has the characteristics of eliminating signal tailing and avoiding interference and misjudgment.

[0004] According to the fiber measurement data compensation method provided by the embodiment of the present application, the following steps are included:

[0005] The first measurement data set is preprocessed based on the noise mean value of the first measurement data set of the measured optical fiber line, and a first measurement data set without noise is obtained. The blind area length in the measurement curve represented by the first measurement data set is not less than a first preset value;

[0006] The second measurement data set is preprocessed based on the noise mean value of the second measurement data set of the measured optical fiber line, and a second measurement data set without noise is obtained. The blind area length in the measurement curve represented by the second measurement data set is not greater than a second preset value, and the second preset value is not greater than the first preset value;

[0007] The end position of the measured optical fiber line is determined based on the second measurement data set without noise.

[0008] The reference point position of compensation is determined based on the parameters of the measurement signal corresponding to the end position and the distance value of the previous position adjacent to the end position.

[0009] Based on the reference point position and the measurement data in the first measurement data set without noise, a compensation model is determined, so that the deviation between the compensation data set obtained based on the compensation model and the first measurement data set without noise satisfies the preset deviation condition.

[0010] Subtracting the compensation data set from the first set of measurement data after removing noise obtains a set of compensated measurement data.

[0011] Further, the determination of the end position of the measured optical fiber line based on the second set of measurement data after removing noise comprises:

[0012] Based on the order of occurrence of the measurement data, the position of the first data collection point in the second set of measurement data after removing noise which is less than a preset signal intensity value is taken as the end position, and the preset signal intensity value is not less than 5dB and not greater than 6dB.

[0013] Further, the determination of the compensation reference point position based on the parameter of the measurement signal corresponding to the end position and the distance value of the previous position adjacent to the end position comprises:

[0014] Based on

[0015]

[0016] The reference point position is obtained, B is the reference point position, EP is the end position, N is the preset signal intensity value, M is the measurement signal intensity reduction multiple, a is the attenuation coefficient of the measurement signal, and d is the distance value of the previous position adjacent to the end position.

[0017] Further, the determination of the compensation model based on the reference point position and the measurement data in the first set of measurement data after removing noise so that the deviation between the set of compensation data obtained based on the compensation model and the first set of measurement data after removing noise satisfies a preset deviation condition comprises:

[0018] Based on

[0019]

[0020] The parameters A and T of the compensation model are obtained, B is the reference point position, is a preset compensation model, A is a coefficient, X is the serial number of each data collection point in the first set of measurement data after removing noise, T is a time constant and 1000≤T≤20000, Max is the number of measurement data in the first set of measurement data after removing noise, and D2(x) is the first set of measurement data after removing noise;

[0021] The compensation model is obtained based on the parameters A and T and the preset compensation model.

[0022] Further, the compensation model determination module is configured to determine a compensation model based on the reference point position and the measurement data in the first measurement data set after noise removal, so that a deviation between a compensation data set obtained based on the compensation model and the first measurement data set after noise removal satisfies a preset deviation condition.

[0023] The compensation data set is obtained based on the compensation model and the first measurement data set after noise removal.

[0024] Further, the compensation device for optical fiber measurement data further comprises:

[0025] The filtered measurement data set is obtained by filtering the compensated measurement data set.

[0026] Further, the compensation device for optical fiber measurement data further comprises:

[0027] The final data set is obtained by performing logarithmic operation on the filtered measurement data set.

[0028] According to the compensation device for optical fiber measurement data provided in the embodiment of the present application, the following technical effects are achieved.

[0029] The first preprocessing module is configured to perform preprocessing on the first measurement data set of the measured optical fiber line based on the noise mean value of the first measurement data set, to obtain a first measurement data set after noise removal, and the length of the blind area in the measurement curve represented by the first measurement data set is not less than a first preset value.

[0030] The second preprocessing module is configured to perform preprocessing on the second measurement data set of the measured optical fiber line based on the noise mean value of the second measurement data set, to obtain a second measurement data set after noise removal, and the length of the blind area in the measurement curve represented by the second measurement data set is not greater than a second preset value, and the second preset value is not greater than the first preset value.

[0031] The end determination module is configured to determine the end position of the measured optical fiber line based on the second measurement data set after noise removal.

[0032] The reference point determination module is configured to determine a compensation reference point position based on the parameter of the measurement signal corresponding to the end position and the distance value of the previous position adjacent to the end position.

[0033] The compensation model determination module is configured to determine a compensation model based on the reference point position and the measurement data in the first measurement data set after noise removal, so that a deviation between a compensation data set obtained based on the compensation model and the first measurement data set after noise removal satisfies a preset deviation condition.

[0034] A measurement data compensation module is configured to subtract the compensation data set from the first measurement data set to obtain a compensated measurement data set.

[0035] An apparatus provided by the embodiment of the present application comprises a memory and a processor.

[0036] The memory is configured to store a program.

[0037] The processor is configured to execute the program to implement each step of the compensation method for optical fiber measurement data.

[0038] A storage medium provided by the embodiment of the present application stores a computer program, which, when executed by a processor, implements each step of the compensation method for optical fiber measurement data.

[0039] The compensation method for optical fiber measurement data, the device, the apparatus and the storage medium provided by the present application can pre-process a first measurement data set of a measured optical fiber line based on a noise mean value of the first measurement data set to obtain a first measurement data set with noise removed, and the length of a blind area in a measurement curve represented by the first measurement data set is not less than a first preset value. Then, a second measurement data set of the measured optical fiber line is pre-processed based on a noise mean value of the second measurement data set to obtain a second measurement data set with noise removed, and the length of a blind area in a measurement curve represented by the second measurement data set is not greater than a second preset value, which is not greater than the first preset value. The end position of the measured optical fiber line is determined based on the second measurement data set with noise removed. The reference point position of compensation is determined based on a parameter of a measurement signal corresponding to the end position and a distance value of a previous position adjacent to the end position. A compensation model is determined based on the reference point position and measurement data in the first measurement data set with noise removed, so that the deviation between a compensation data set obtained based on the compensation model and the first measurement data set with noise removed satisfies a preset deviation condition. Finally, a compensated measurement data set is obtained by subtracting the compensation data set from the first measurement data set with noise removed. The compensation method for optical fiber measurement data can select the position of the reference point according to the condition of the measured optical fiber line, so that the tail compensation model obtained based on the reference point has self-adaptability, can effectively remove the OTDR signal tail, accurately reflect the information of the optical fiber line, solve the tail problem of the OTDR signal, and avoid the occurrence of misjudgment and interference. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings belong to the protection scope of the present application.

[0041] Figure 1 is a flow chart of a compensation method of optical fiber measurement data according to an exemplary embodiment;

[0042] Figure 2 is a structural diagram of a compensation device of optical fiber measurement data according to an exemplary embodiment;

[0043] Figure 3 is a structural diagram of an apparatus according to an exemplary embodiment. DETAILED DESCRIPTION

[0044] In order to make the technical solutions of the embodiments of the present application or the prior art clearer, the accompanying drawings needed in the embodiments or prior art description will be briefly introduced. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on these drawings belong to the protection scope of the present application.

[0045] Referring to Figure 1 The embodiments of the present application provide a compensation method of optical fiber measurement data, which can include the following steps:

[0046] 101, pre-process the first measurement data set based on the noise mean value of the measured optical fiber line, to obtain a first measurement data set without noise, and the blind area length in the measurement curve represented by the first measurement data set is not less than a first preset value.

[0047] In the measurement of optical fiber line by using optical time domain reflectometer, the corresponding measurement curve is generated by transmitting pulse signal and receiving corresponding reflected signal, in which the horizontal coordinate of the measurement curve is distance value and the vertical coordinate is returned signal level value. Because the pulse light wave is propagated in the optical fiber line, the data collection points constituting the measurement curve are actually discrete measurement points. In a complete measurement process, the measurement data set is obtained by each measurement point. In general measurement, the adjustment of test signal amplification circuit, laser output power and other parameters will change the pulse signal width accordingly. In practice, the longer the pulse width, the smoother the curve obtained but the largest blind area, the shorter the pulse width, the smallest blind area but the noise is very large, and other widths are between the two. Therefore, the noise average of the first measurement data set of the measured optical fiber line with signal tail can be preprocessed, that is, the average value of the noise data is taken as the baseline value, and the data (signal level value) of each collection point in the first measurement data set D1 is subtracted from the baseline value to obtain the measurement data set D2 after removing the baseline. In order to limit the degree of tailing, the length of blind area not less than the first preset value can be taken as the width of general blind area.

[0048] 102、Based on the noise average of the second measurement data set of the measured optical fiber line, the second measurement data set is preprocessed to obtain the second measurement data set after removing noise, and the length of the blind area in the measurement curve represented by the second measurement data set is not greater than the second preset value, and the second preset value is not greater than the first preset value.

[0049] Similarly, by reducing the signal strength of OTDR to no tailing, the optical fiber line is measured again to obtain a set of measurement data, and the average value of the noise data is taken as the baseline value. Each data in this set of measurement data is subtracted from the baseline value to obtain the data after removing the baseline. Generally, the second measurement data set is obtained by reducing the signal strength of OTDR to reduce the blind area range of the measurement curve.

[0050] It can be understood that the first preset value and the second preset value can be adjusted by those skilled in the art according to the specific measurement line, which is not limited in the present application.

[0051] 103、Based on the second measurement data set after removing noise, the end position of the measured optical fiber line is determined.

[0052] Because the appearance of each data collection point of the measurement curve is generated according to the order of the received returned measurement signals, the position of the first data collection point less than the preset signal strength value in the second measurement data set after removing the noise can be taken as the end position based on the order of the appearance of the measurement data, wherein the preset signal strength value is not less than 5 dB and not greater than 6 dB. For example, the first data sequence number less than 5 dB can be found in the order of the sequence number increasing, and is defined as the end position of the measured optical fiber line.

[0053] 104. Determine the compensated reference point position based on the parameter of the measurement signal corresponding to the end position and the distance value of the previous position adjacent to the end position.

[0054] Specifically, the reference point position B can be calculated by combining the measurement signal strength reduction multiple M, the attenuation coefficient a of the measurement signal, and the distance value d of the previous position adjacent to the end position:

[0055]

[0056] Wherein B is the reference point position, EP is the end position, N is the preset signal strength value, which can generally take a value of 5. Wherein a is a typical value of the attenuation coefficient of the laser wavelength selected by the OTDR when performing line measurement, which takes a value of 0.2 dB / km when the laser wavelength is greater than or equal to 1450 nm and less than or equal to 1650 nm, and takes a value of 0.33 dB / km when the laser wavelength is equal to 1310 nm. The distance value d of the previous position adjacent to the end position is C / 2nf, wherein C is the propagation speed of light in vacuum, n is the refractive index of the line, and f is the sampling frequency of the OTDR.

[0057] 105. Determine the compensation model based on the reference point position and the measurement data in the first measurement data set after removing the noise, so that the deviation between the compensated data set obtained based on the compensation model and the first measurement data set after removing the noise satisfies the preset deviation condition.

[0058] Specifically, the mathematical model for signal compensation can be:

[0059]

[0060] Wherein A is a coefficient, x is the sequence number of the OTDR measurement data, and T is a time constant. A set of parameters A and T are obtained by minimizing the sum of squares of the difference between the mathematical model Dm and the data after baseline removal, i.e., the first measurement data set D2 after removing the noise, and the calculation formula is:

[0061]

[0062] The parameters A and T of the compensation model are obtained, and B is the reference point position, For the preset compensation model, A is a coefficient, X is the serial number of each data collection point in the first set of measurement data after noise removal, T is a time constant and 1000≤T≤20000, Max is the number of measurement data in the first set of measurement data after noise removal, and D2(x) is the first set of measurement data after noise removal. The compensation model can be obtained by using the parameters A and T and the preset compensation model.

[0063] The time constant T is in the range of 1000≤T≤20000.

[0064] 106、The first set of measurement data after noise removal is subtracted by the set of compensation data to obtain a set of measurement data after compensation.

[0065] A set of compensation data Db is calculated by using the obtained mathematical model parameters A and T and the mathematical model Dm. The data set D2 is subtracted by the compensation data Db to obtain the data D3 after tail compensation.

[0066] The compensation method for the optical fiber measurement data can adaptively select the reference point position by establishing a compensation model for the tail signal of the optical fiber and combining the signal parameters of the measured optical fiber line, so that the compensation data of the tail signal determined according to the parameters can most approximate the optimal solution of the tail signal. The tail compensation data can effectively remove the OTDR signal tail, accurately reflect the information of the optical fiber line, and solve the tail problem of the OTDR signal.

[0067] To further optimize the technical solution, the set of measurement data after compensation can be filtered to obtain a set of filtered measurement data after the data D3 after tail compensation is obtained. Thus, the interference in the measurement signal after compensation is further filtered out, the accuracy of eliminating the tail signal is maximized, and the tail problem of the OTDR signal is solved.

[0068] It should be noted that the specific data filtering method can be selected by those skilled in the art according to actual needs, which is not limited in the present application.

[0069] To further facilitate the use of data and observation of users, in another specific embodiment of the present application, the set of filtered measurement data can also be subjected to logarithmic operation to obtain a final set of compensation data, which is more in line with the actual observation needs and habits.

[0070] Based on the same design idea, referring to Figure 2 The embodiment of the present application also provides an optical fiber measurement data compensation device. The device can implement the steps of the above-mentioned optical fiber measurement data compensation method when in operation. The device can include:

[0071] The first preprocessing module 201 is configured to preprocess a first measurement data set based on a noise mean value of the first measurement data set of the optical fiber line to be measured, to obtain a first measurement data set with noise removed, and the blind area length in the measurement curve represented by the first measurement data set is not less than a first preset value.

[0072] The second preprocessing module 202 is configured to preprocess a second measurement data set based on a noise mean value of the second measurement data set of the optical fiber line to be measured, to obtain a second measurement data set with noise removed, and the blind area length in the measurement curve represented by the second measurement data set is not greater than a second preset value, and the second preset value is not greater than the first preset value.

[0073] The end determination module 203 is configured to determine an end position of the optical fiber line to be measured based on the second measurement data set with noise removed.

[0074] The reference point determination module 204 is configured to determine a compensated reference point position based on a parameter of a measurement signal corresponding to the end position and a distance value of a previous position adjacent to the end position.

[0075] The compensation model determination module 205 is configured to determine a compensation model based on the reference point position and measurement data in the first measurement data set with noise removed, so that a deviation between a compensation data set obtained based on the compensation model and the first measurement data set with noise removed satisfies a preset deviation condition. and

[0076] The measurement data compensation module 206 is configured to subtract the compensation data set from the first measurement data set with noise removed to obtain a compensated measurement data set.

[0077] Further, the end determination module 203 is specifically configured to determine the position of a data collection point smaller than a preset signal intensity value in the first measurement data set with noise removed as the end position based on the order of occurrence of the measurement data, and the preset signal intensity value is not less than 5 dB and not greater than 6 dB.

[0078] Further, the reference point determination module 204 is specifically configured to determine the reference point position based on

[0079]

[0080] The reference point position B is obtained, EP is the end position, N is the preset signal intensity value, M is the measurement signal intensity reduction multiple, a is the measurement signal attenuation coefficient, and d is the distance value of the previous position adjacent to the end position.

[0081] Further, the compensation model determination module 205 is specifically configured to determine the compensation model based on

[0082]

[0083] obtaining parameters A and T of the compensation model, B being a reference point position, the preset compensation model, A being a coefficient, X being a serial number of each data collection point in the first set of measurement data after noise removal, T being a time constant and 1000T20000, Max being a number of measurement data in the first set of measurement data after noise removal, and D2(x) being the first set of measurement data after noise removal. The compensation model is obtained based on the parameters A and T and the preset compensation model.

[0084] Further, the compensation model determination module 205 is further configured to obtain a set of compensated data based on the compensation model and the first set of measurement data after noise removal.

[0085] Further, the compensation device for optical fiber measurement data further comprises a filtering module configured to filter the set of compensated measurement data to obtain a set of filtered measurement data.

[0086] Further, the compensation device for optical fiber measurement data further comprises a conversion module configured to perform a logarithm operation on the set of filtered measurement data to obtain a set of final compensated data.

[0087] The compensation device for optical fiber measurement data has the same beneficial effects as the compensation method for optical fiber measurement data described above, and the specific implementation manner can refer to the embodiments of the compensation method for optical fiber measurement data described above, which will not be described here in detail.

[0088] Referring to Figure 3 The embodiments of the present application further provide a device, which can include a memory 301 and a processor 302.

[0089] The memory 301 is configured to store a program.

[0090] The processor 302 is configured to execute the program to implement each step of the compensation method for optical fiber measurement data as described in the above embodiments.

[0091] The embodiments of the present application further provide a storage medium having a computer program stored thereon, which is executed by a processor to implement each step of the compensation method for optical fiber measurement data as described in the above embodiments.

[0092] In the description of the disclosure, reference to "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that a particular feature, structure, material or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present disclosure. Descriptive expressions of the above terms in the specification do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0093] The above description includes examples of one or more embodiments. Of course, it is not possible to describe all possible combinations of components or methods for describing the above embodiments, but those of ordinary skill in the art should recognize that various embodiments can be further combined and arranged. Therefore, the embodiments described herein are intended to cover all such changes, modifications and variations that fall within the scope of the appended claims. In addition, with respect to the term "comprising" used in the specification or claims, the scope of the term is similar to the term "including", as explained in the context of "including" used as a transitional phrase in the claims. In addition, the use of any one term "or" in the specification or claims is intended to mean "non-exclusive or", as explained in the context of "or" used as a transitional phrase in the claims.

[0094] The above description is merely a specific implementation of the present disclosure, but the protection scope of the present disclosure is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present disclosure, which should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure should be subject to the protection scope of the claims.

Claims

1. A method of compensating for optical fiber measurement data, characterized by, The method comprises the following steps: preprocessing a first measurement data set of a measured optical fiber line based on a noise mean value of the first measurement data set to obtain a first measurement data set after noise removal, a blind area length in a measurement curve represented by the first measurement data set being not less than a first preset value; preprocessing a second measurement data set of the measured optical fiber line based on a noise mean value of the second measurement data set to obtain a second measurement data set after noise removal, a blind area length in a measurement curve represented by the second measurement data set being not greater than a second preset value, the second preset value being not greater than the first preset value; determining an end position of the measured optical fiber line based on the second measurement data set after noise removal; determining a compensated reference point position based on a parameter of a measurement signal corresponding to the end position and a distance value of a previous position adjacent to the end position; determining a compensation model based on the reference point position and measurement data in the first measurement data set after noise removal, so that a deviation between a compensation data set obtained based on the compensation model and the first measurement data set after noise removal satisfies a preset deviation condition; subtracting the compensation data set from the first measurement data set after noise removal to obtain a compensated measurement data set; the determination of the compensated reference point position based on the parameter of the measurement signal corresponding to the end position and the distance value of the previous position adjacent to the end position comprises: the determination of the end position of the measured optical fiber line based on the second measurement data set after noise removal comprises: obtaining the reference point position, B is the reference point position, EP is the end position, N is a preset signal strength value, M is a measured signal strength reduction multiple, is an attenuation coefficient of the measured signal, and d is a distance value of a previous position adjacent to the end position.

2. The method of claim 1, wherein, based on an order of occurrence of the measurement data, a position of a first data collection point less than a preset signal intensity value in the second measurement data set after noise removal is taken as the end position, the preset signal intensity value being not less than 5 dB and not greater than 6 dB. the determination of the compensation model based on the reference point position and the measurement data in the first measurement data set after noise removal, so that the deviation between the compensation data set obtained based on the compensation model and the first measurement data set after noise removal satisfies the preset deviation condition comprises:

3. The method of claim 1, wherein, the determination of the compensation model based on the parameter A and T and the preset compensation model. the determination of the compensation model based on the reference point position and the measurement data in the first measurement data set after noise removal, so that the deviation between the compensation data set obtained based on the compensation model and the first measurement data set after noise removal satisfies the preset deviation condition further comprises: obtaining parameters A and T of the compensation model, and B is the position of the reference point, A is a coefficient, X is the serial number of each data collection point in the first set of measurement data after noise removal, T is a time constant, and Max is the number of measurement data in the first set of measurement data after noise removal, the first set of measurement data after noise removal; obtaining the compensation data set based on the compensation model and the first measurement data set after noise removal.

4. The method of claim 3, wherein, The method further comprises the following steps: filtering the compensated measurement data set to obtain a filtered measurement data set.

5. The method of claim 1, wherein, The method further comprises the following steps: performing a logarithmic operation on the filtered measurement data set to obtain a final data set.

6. The method of claim 5, wherein, The method comprises the following steps: ​ 7. An apparatus for compensating optical fiber measurement data, characterized by, ​ The first preprocessing module is configured to preprocess a first measurement data set of the measured optical fiber line based on a noise mean value of the first measurement data set, to obtain a first measurement data set with noise removed, and the blind area length in a measurement curve represented by the first measurement data set is not less than a first preset value. The second preprocessing module is configured to preprocess a second measurement data set of the measured optical fiber line based on a noise mean value of the second measurement data set, to obtain a second measurement data set with noise removed, and the blind area length in a measurement curve represented by the second measurement data set is not greater than a second preset value, and the second preset value is not greater than the first preset value. The end determination module is configured to determine an end position of the measured optical fiber line based on the second measurement data set with noise removed. The reference point determination module is configured to determine a compensated reference point position based on a parameter of a measurement signal corresponding to the end position and a distance value of a previous position adjacent to the end position, including: The compensation model determination module is configured to determine a compensation model based on the reference point position and measurement data in the first measurement data set with noise removed, so that a deviation between a compensation data set obtained based on the compensation model and the first measurement data set with noise removed satisfies a preset deviation condition; and obtaining the reference point position, B is the reference point position, EP is the end position, N is a preset signal strength value, M is a measured signal strength reduction multiple, is an attenuation coefficient of the measured signal, and d is a distance value of a previous position adjacent to the end position. The measurement data compensation module is configured to subtract the compensation data set from the first measurement data set with noise removed to obtain a compensated measurement data set. The memory and the processor; 8. An apparatus, comprising: The memory is configured to store a program; The processor is configured to execute the program to implement the steps of the optical fiber measurement data compensation method in any one of claims 1 to 6. The computer program is executed by the processor to implement the steps of the optical fiber measurement data compensation method in any one of claims 1 to 6. ​ 9. A storage medium having stored thereon a computer program, characterized in that ​

Images