One-way measurement system on-line zero calibration method based on optical transmission link

Abstract

The invention discloses a one-way measurement system on-line zero value calibration method based on an optical transmission link, which belongs to the technical field of zero value calibration, and utilizes the characteristic that two channels on the same DAC / ADC chip are consistent in switching time delay zero value change, and compares the time delay difference change of a reference signal and a signal to be calibrated, so as to calibrate the zero value of the one-way measurement system. And correcting the absolute zero value calibrated during delivery according to the variable quantity to realize online zero value calibration.

Description

Technical Field

[0001] The present application belongs to the technical field of zero value calibration, and in particular, relates to an online zero value calibration method for a unidirectional measurement system based on an optical transmission link. Background Art

[0002] The aircraft one-way measurement system receives the measurement signal transmitted by the target aircraft, completes the measurement of the target's distance, speed, time difference, etc., provides data support for target positioning, orbit determination and test identification, and can also complete its own positioning calculation in combination with the received multiple target measurement signals and time information.

[0003] For a unidirectional measurement system, unlike a bidirectional measurement system, there is no need to transmit a signal to the target, and the measurement can be completed only by receiving the target signal. The measured distance value includes the actual distance of the target and the measurement zero value introduced by the measurement system equipment itself, so it is necessary to obtain the distance zero value in real time and deduct it. The reason why the system measures the real-time zero value is that the zero value of the measurement system equipment itself will drift due to the influence of the device and the temperature change. In addition, for some devices, the phase of the device's power-on and power-off signal will change each time, causing the power-on and power-off zero value to change, and online zero value calibration is required. For a bidirectional measurement system, the real-time zero value can be obtained through a bidirectional closed-loop link, while the unidirectional measurement system does not have an uplink transmission link, and its distance zero value cannot be obtained through an online bidirectional closed-loop real-time measurement. In addition, the use of optical transmission links for data transmission between devices in the measurement system can improve signal transmission efficiency and increase transmission distance, but the introduction of photoelectric conversion, synchronous transmission and other links brings uncertainty to the system zero value. Therefore, the conventional online zero value calibration method is difficult to meet the requirements of a unidirectional measurement system based on an optical transmission link.

[0004] The unidirectional measurement system receives the target's measurement signal to complete the measurement. To calibrate the zero value of the equipment at a single measurement station, on the one hand, it is necessary to use instruments such as oscilloscopes, which are complicated to operate and are not suitable for zero value calibration of the system before field missions. On the other hand, the zero value of the equipment will change after turning on and off due to the influence of components, so zero value calibration is required after each power-on.

[0005] Therefore, there is an urgent need for an online zero-value calibration method based on an optical transmission link, which detects the zero-value change after each startup of the unidirectional measurement system and corrects the absolute value according to the change for measurement data processing. Summary of the invention

[0006] The purpose of the present application is to overcome the problems of the prior art and disclose an online zero-value calibration method for a unidirectional measurement system based on an optical transmission link. The method utilizes the characteristic that the zero-value changes of the power-on and power-off delays of two channels on the same DAC / ADC chip are consistent. By comparing the changes in the delay difference between a reference signal and a signal to be calibrated, the absolute zero value calibrated at the factory is corrected according to the change, thereby achieving online zero-value calibration.

[0007] The purpose of this application is achieved through the following technical solutions:

[0008] An online zero value calibration method for a unidirectional measurement system based on an optical transmission link, the online zero value calibration method for the unidirectional measurement system comprising:

[0009] S1: The unidirectional measurement system is calibrated to absolute zero value before leaving the factory, and the factory absolute zero value is recorded as t0;

[0010] S2: The front and back ends of the unidirectional measurement system share a common clock through a frequency source;

[0011] S3: Generate a source signal for zero-value calibration in the front-end FPGA and send it to two channels ch1 and ch2 of the front-end DAC chip through an optical interface;

[0012] S4: The analog electrical signal output by the ch1 channel of the front-end DAC chip enters the working channel through the array ADC, and reaches the front-end signal processing module after optical interface conversion. After completing the protocol conversion, the digital optical signal is transmitted to the back-end FPGA via optical fiber;

[0013] S5: The back-end FPGA receives the signal to be calibrated from the front-end, enters the signal processing module after completing the protocol conversion, and then is sent to the ch1 channel of the back-end DAC through the photoelectric conversion of the optical interface;

[0014] The signal of the ch1 channel of the back-end DAC is looped back to the ch1 channel of the back-end ADC as the signal to be calibrated for comparison with the reference signal, and the ch2 channel of the back-end DAC is the task signal output channel;

[0015] S6: The signal output by the ch2 channel of the front-end DAC chip is used as a reference signal and is directly sent to the ch2 channel of the back-end ADC through a cable for comparison with the signal to be calibrated;

[0016] S7: The back-end ADC receives the signal to be calibrated sent by the ch1 channel of the back-end DAC and the reference signal sent by the ch2 channel of the front-end DAC chip, and sends them to the optical interface to complete the photoelectric conversion, and then sends them to the delay measurement module to measure the delay difference between the signal to be calibrated and the reference signal, that is, the zero value difference is recorded as Δt0;

[0017] S8: After the unidirectional measurement system is turned on before each task, steps S2 to S7 are repeated to measure the zero value difference between the signal to be calibrated in the current state and the reference signal, which is recorded as Δt1;

[0018] S9: Calculate Δt1-Δt0 to get Δt, where Δt is the zero value change of the unidirectional measurement system. Thus, by t0+Δt, the system zero value calibration of this task can be completed.

[0019] According to a preferred embodiment, in step S4, the analog electrical signal output by the channel ch1 of the front-end DAC chip is used as the signal to be calibrated for measuring the zero value of the working channel.

[0020] According to a preferred implementation, in step S4, the data processed by the signal processing module of the front end is converted into a protocol via the synchronous transmission module of the front end.

[0021] According to a preferred implementation, in step S5, the back-end FPGA receives the signal to be calibrated sent by the front-end, and completes the protocol conversion through the back-end synchronous transmission module.

[0022] According to a preferred embodiment, in step S5, the on / off zero value change of the ch2 channel of the back-end DAC is consistent with that of the ch1 channel of the back-end DAC.

[0023] According to a preferred embodiment, in step S7, the ch1 channel to-be-calibrated signal of the back-end DAC and the ch2 channel reference signal of the front-end DAC chip are consistent with each other after the switching zero value change of the ADC.

[0024] The aforementioned main scheme of the present application and its further options can be freely combined to form multiple schemes, all of which are schemes that can be adopted and claimed for protection in the present application. After understanding the scheme of the present application, those skilled in the art can understand that there are multiple combinations based on the prior art and common knowledge, all of which are technical schemes to be protected by the present application, and they are not exhaustively listed here.

[0025] Beneficial effects of this application:

[0026] 1) According to the nature of the task, this application method does not require on-site online calibration of the equipment zero value, and directly detects the zero value change online, and then corrects the system zero value in real time. The operation is simple and does not require high professionalism, which improves the efficiency of zero value calibration at the task site.

[0027] 2) By detecting and comparing the zero-value changes of the signal channel to be calibrated and the reference signal channel, the measurement error introduced by the calibration part is offset, and the detection result can fully characterize the zero-value changes of the task channel.

[0028] 3) Zero value does not require instrument measurement, and on-site operation is simpler and faster.

[0029] 4) Perform phase measurement in the delay measurement module. The phase measurement method has high accuracy and is conducive to improving the accuracy of zero value calibration.

[0030] 5) The device generates internal sources, which can be configured into any task mode to ensure the authenticity and reliability of zero value calibration without the need for additional configuration of analog sources.

[0031] 6) This application is applicable to multi-station time difference positioning systems for cooperative targets and non-cooperative targets, and has a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of an online zero-value calibration method of a unidirectional measurement system based on an optical transmission link of the present application. DETAILED DESCRIPTION

[0033] The following describes the embodiments of the present application through specific examples, and those skilled in the art can easily understand other advantages and effects of the present application from the contents disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict.

[0034] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0035] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the application is usually placed when in use. They are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as a limitation on the present application. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0036] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components are required to be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0037] In the description of this application, it should also be noted that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to specific circumstances.

[0038] In addition, the present application would like to point out that, in the present application, unless the specific structure, connection relationship, positional relationship, power source relationship, etc. are specifically written out, the structure, connection relationship, positional relationship, power source relationship, etc. involved in the present application are all known by those skilled in the art on the basis of the prior art without creative work.

[0039] Example 1

[0040] refer to Figure 1 As shown, the figure shows an online zero-value calibration method for a unidirectional measurement system based on an optical transmission link, and the online zero-value calibration method for a unidirectional measurement system includes the following steps.

[0041] 1) The absolute zero value calibration is completed at the factory, and the factory absolute zero value is recorded as t0. The factory zero value calibration can be carried out in a conventional way, which is not described in detail here. The zero value difference between the factory calibration signal and the reference signal is recorded as Δt0 through the following 2) to 7).

[0042] 2) The front end and back end are clocked by a frequency source.

[0043] 3) Generate a source signal for zero-value calibration in the front-end FPGA and send it to two channels ch1 and ch2 of the same DAC chip through an optical interface.

[0044] 4) The analog electrical signal output by the front-end DAC chip ch1 is used as the calibration signal for measuring the zero value of the working channel. It enters the working channel through the array ADC, reaches the signal processing module after conversion by the optical interface, and then is transmitted to the back-end FPGA via optical fiber after the digital optical signal after protocol conversion by the synchronous transmission module.

[0045] 5) The back-end FPGA receives the signal to be calibrated from the front end, completes the protocol conversion through the synchronous transmission module, enters the signal processing module, and then sends it to the ch1 of the same DAC through the photoelectric conversion of the optical interface. The signal of ch1 is looped back to the ch1 channel of the ADC as the signal to be calibrated for comparison with the reference signal. ch2 is the task signal output channel, and its zero value change of power on and off is consistent with ch1.

[0046] 6) The signal output by the front-end DAC chip ch2 is used as a reference signal and is directly sent to the ch2 channel of the back-end ADC through a cable for comparison with the signal to be calibrated.

[0047] 7) The back-end ADC receives the signal to be calibrated from ch1 and the reference signal from ch2, and sends them to the optical interface to complete the photoelectric conversion, and then sends them to the delay measurement module to measure the delay difference between the signal to be calibrated and the reference signal, that is, the zero value difference is recorded as Δt0. The delay measurement method is the general signal correlation method, which is not described in detail here.

[0048] 8) After the equipment is turned on before each task, the zero-value difference between the signal to be calibrated in the current state and the reference signal is measured through the above 2) to 7) and recorded as Δt1.

[0049] 9) Calculate Δt1-Δt0 to get Δt, which is the zero value change of the unidirectional measurement system. Through t0+Δt, the system zero value calibration of this task can be completed.

[0050] According to the nature of the task, the method of this application does not require on-site online calibration of the zero value of the equipment, but directly detects the change of zero value online, and then corrects the zero value of the system in real time. It is easy to operate, does not require high professionalism, and improves the efficiency of zero value calibration at the task site. By detecting and comparing the zero value change of the signal channel to be calibrated and the reference signal channel, the measurement error introduced by the calibration part is offset, and the detection result can fully characterize the zero value change of the task channel. The zero value does not require instrument measurement, and the on-site operation is simpler and faster. Phase measurement is performed in the delay measurement module, and the phase measurement method has high accuracy, which is conducive to improving the accuracy of zero value calibration. The source is generated internally by the device and can be configured to any task mode to ensure the authenticity and reliability of the zero value calibration, without the need for additional configuration of the analog source. The present application is applicable to multi-station time difference positioning systems for cooperative targets and non-cooperative targets, and has a wide range of applications.

[0051] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. An online zero value calibration method for a unidirectional measurement system based on an optical transmission link, characterized in that: The one-way measurement system online zero value calibration method comprises: S1: The unidirectional measurement system is calibrated to absolute zero value before leaving the factory, and the factory absolute zero value is recorded as t0; S2: The front and back ends of the unidirectional measurement system share a common clock through a frequency source; S3: Generate a source signal for zero-value calibration in the front-end FPGA and send it to two channels ch1 and ch2 of the front-end DAC chip through an optical interface; S4: The analog electrical signal output by the ch1 channel of the front-end DAC chip enters the working channel through the array ADC, and reaches the front-end signal processing module after optical interface conversion. After completing the protocol conversion, the digital optical signal is transmitted to the back-end FPGA via optical fiber; S5: The back-end FPGA receives the signal to be calibrated from the front-end, enters the signal processing module after completing the protocol conversion, and then is sent to the ch1 channel of the back-end DAC through the photoelectric conversion of the optical interface; The signal of the ch1 channel of the back-end DAC is looped back to the ch1 channel of the back-end ADC as the signal to be calibrated for comparison with the reference signal, and the ch2 channel of the back-end DAC is the task signal output channel; S6: The signal output from the ch2 channel of the front-end DAC chip is used as a reference signal and is directly sent to the ch2 channel of the back-end ADC through a cable for comparison with the signal to be calibrated; S7: The back-end ADC receives the signal to be calibrated sent by the ch1 channel of the back-end DAC and the reference signal sent by the ch2 channel of the front-end DAC chip, and sends them to the optical interface to complete the photoelectric conversion, and then sends them to the delay measurement module to measure the delay difference between the signal to be calibrated and the reference signal, that is, the zero value difference is recorded as Δt0; S8: After the unidirectional measurement system is turned on before each task, steps S2 to S7 are repeated to measure the zero value difference between the signal to be calibrated in the current state and the reference signal, which is recorded as Δt1; S9: Calculate Δt1-Δt0 to get Δt, where Δt is the zero value change of the unidirectional measurement system. Thus, by t0+Δt, the system zero value calibration of this task can be completed.

2. The online zero value calibration method of a unidirectional measurement system according to claim 1, characterized in that: In step S4, the analog electrical signal output by the channel ch1 of the front-end DAC chip is used as a signal to be calibrated for measuring the zero value of the working channel.

3. The online zero value calibration method of a unidirectional measurement system according to claim 2, characterized in that: In step S4, the data processed by the signal processing module of the front end is converted into a protocol by the synchronous transmission module of the front end.

4. The online zero value calibration method of a unidirectional measurement system according to claim 1, characterized in that: In step S5, the back-end FPGA receives the signal to be calibrated sent by the front-end, and completes the protocol conversion through the back-end synchronous transmission module.

5. The online zero value calibration method for a unidirectional measurement system according to claim 1, characterized in that: In step S5, the switching zero value change of the ch2 channel of the back-end DAC is consistent with the ch1 channel of the back-end DAC.

6. The online zero value calibration method for a unidirectional measurement system according to claim 1, characterized in that: In step S7, the ch1 channel to-be-calibrated signal of the back-end DAC and the ch2 channel reference signal of the front-end DAC chip are consistent with each other after the switching zero value change of the ADC.

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