Fully automatic calibration method for weather radar

Abstract

The present application relates to the technical field of weather radars, and discloses a fully automatic calibration method for a weather radar. In the method, multiple sets of calibration differential signals are injected into a receiver of a weather radar to be calibrated, wherein at least two sets of calibration differential signals differ in injection power, at least two sets of calibration differential signals differ in frequency offset, and at least two sets of calibration differential signals differ in spectral width; then, by combining the injection power, frequency offset, and spectral width of each set of calibration differential signals and measured values of intensity, velocity, and spectral width under the corresponding calibration differential signals, the unified calibration of the intensity, velocity, spectral width, differential reflectivity factor, and differential propagation phase shift can be accomplished. The method innovatively unifies various radar parameters into a single calibration process while ensuring comprehensive calibration of those radar parameters, thereby greatly reducing calibration time and items, optimizing the calibration process, and improving the calibration efficiency.

Description

Full-automatic calibration method of weather radar TECHNICAL FIELD

[0001] The present application relates to the technical field of weather radar, and in particular to a full-automatic calibration method of weather radar. BACKGROUND

[0002] The weather radar can complete real-time monitoring of occurrence, development, intensity and position of weather targets in the range around the site, so as to obtain distance, azimuth, intensity, speed, spectral width, differential reflectivity factor, differential propagation phase shift, differential propagation phase shift rate, correlation coefficient and other echo and inversion products of weather targets such as clouds and rain relative to the radar, and realize automatic identification, tracking and analysis of weather targets based on these inversion products, effectively monitor and warn dangerous weather, provide rich and comprehensive analysis data for weather forecast personnel, and effectively improve weather guarantee capability.

[0003] At present, weather radar systems gradually adopt dual-polarization system, and the dual-polarization parameters measured by the weather radar are affected by the fluctuation state of the hardware of the weather radar itself, the data quality is reduced, and it is not conducive to the analysis and prediction of weather processes. Therefore, it is necessary to calibrate the weather radar, which can effectively reduce the error in the weather radar system and ensure that it can accurately measure precipitation or other weather targets in the atmosphere. TECHNICAL PROBLEM

[0004] At present, the calibration process of the weather radar is either not comprehensive or too cumbersome, and the calibration effect is not ideal. TECHNICAL SOLUTION

[0005] In view of the above problems and technical needs, the present application provides a full-automatic calibration method of weather radar, and the technical scheme of the present application is as follows:

[0006] A full-automatic calibration method of weather radar, the full-automatic calibration method comprising:

[0007] Injecting a plurality of groups of calibration differential signals into the receiver of the weather radar to be calibrated in turn, the injection power of at least two groups of calibration differential signals being different, the frequency offset of at least two groups of calibration differential signals being different, and the spectral width of at least two groups of calibration differential signals being different;

[0008] Obtaining intensity measured values, speed measured values, spectral width measured values, differential reflectivity factor measured values and differential propagation phase shift measured values of the weather radar to be calibrated under each group of calibration differential signals;

[0009] The calibration error of intensity is obtained according to the injection power of each group of calibration differential signals and the measured value of intensity of the weather radar to be calibrated under the corresponding calibration differential signal, the calibration error of velocity is obtained according to the frequency offset of each group of calibration differential signals and the measured value of velocity of the weather radar to be calibrated under the corresponding calibration differential signal, the calibration error of spectral width is obtained according to the spectral width of each group of calibration differential signals and the measured value of spectral width of the weather radar to be calibrated under the corresponding calibration differential signal, and the calibration error of differential reflectivity factor and the calibration error of differential propagation phase shift are obtained according to the measured value of differential reflectivity factor and the measured value of differential propagation phase shift of the weather radar to be calibrated under the corresponding calibration differential signal.

[0010] A further technical solution is that the multiple groups of calibration differential signals are sequentially injected into the receiver of the weather radar to be calibrated, including:

[0011] A plurality of different output signals are respectively output by an external signal source, each output signal forms a group of calibration differential signals by outputting two equal calibration signals via a power divider, and the external calibration error of each radar parameter is obtained by injecting the calibration differential signals into the receiver of the weather radar to be calibrated.

[0012] A further technical solution is that the full-automatic calibration method further includes:

[0013] The transmitter of the weather radar to be calibrated is controlled to emit at a plurality of different target powers, and the power measured value of the power coupling port of the weather radar to be calibrated under each target power is measured by using a power meter as an internal calibration reference under the working pulse width.

[0014] A further technical solution is that the multiple groups of calibration differential signals are sequentially injected into the receiver of the weather radar to be calibrated, including:

[0015] The internal calibration source built in the weather radar to be calibrated is controlled to generate a plurality of groups of calibration differential signals, and the internal calibration error of each radar parameter is obtained by injecting the calibration differential signals into the receiver of the weather radar to be calibrated.

[0016] A further technical solution is that the full-automatic calibration method further includes:

[0017] The transmitter of the weather radar to be calibrated is controlled to emit at a plurality of groups of working pulse widths, and the internal power measurement value calculated by the weather radar to be calibrated under each group of working pulse widths is determined, the power error between the internal power measurement value under each working pulse width and the internal calibration reference under the working pulse width is calculated, and the root mean square error of the power errors of all working pulse widths is calculated to obtain the internal and external calibration error of power.

[0018] A further technical solution is that the full-automatic calibration method further includes:

[0019] The internal calibration source is used to perform internal calibration on the weather radar to be calibrated in a detection gap of the weather radar to be calibrated, and internal calibration errors of each radar parameter are obtained;

[0020] When the deviation of the internal calibration error of each radar parameter from the external calibration error of the corresponding radar parameter exceeds a deviation threshold, the internal calibration source of the weather radar to be calibrated is corrected until the deviation of the internal calibration error of the radar parameter from the corresponding external calibration error is within the deviation threshold.

[0021] Further, the calibration error of each radar parameter includes:

[0022] The intensity error corresponding to each set of calibration differential signals is obtained by calculating the error between the intensity measured value of the weather radar to be calibrated under the corresponding calibration differential signal and the intensity theoretical value corresponding to the injection power of the calibration differential signal, and the calibration error of the intensity is obtained by calculating the root mean square error of the intensity errors corresponding to each set of calibration differential signals;

[0023] The velocity error corresponding to each set of calibration differential signals is obtained by calculating the error between the velocity measured value of the weather radar to be calibrated under the corresponding calibration differential signal and the velocity theoretical value corresponding to the frequency offset of the calibration differential signal, and the calibration error of the velocity is obtained by calculating the root mean square error of the velocity errors corresponding to each set of calibration differential signals;

[0024] The spectrum width error corresponding to each set of calibration differential signals is obtained by calculating the error between the spectrum width measured value of the weather radar to be calibrated under the corresponding calibration differential signal and the corresponding spectrum width theoretical value, and the calibration error of the spectrum width is obtained by calculating the root mean square error of the spectrum width errors corresponding to each set of calibration differential signals;

[0025] The calibration error of the differential reflectivity factor is obtained by calculating the root mean square error of the differential reflectivity factor measured values of the weather radar to be calibrated under each set of calibration differential signals;

[0026] The calibration error of the differential propagation phase shift is obtained by calculating the root mean square error of the differential propagation phase shift measured values of the weather radar to be calibrated under each set of calibration differential signals.

[0027] Further, the variation range of the injection power of the calibration differential signal injected into the receiver of the weather radar to be calibrated meets the fluctuation range requirement. Advantages

[0028] The application discloses a full-automatic calibration method of a weather radar, which can automatically calibrate several parameters of a weather radar to be calibrated, such as intensity, speed, spectral width, differential reflectivity factor and differential propagation phase shift, and innovatively unifies the intensity, the speed, the differential reflectivity factor and the differential propagation phase shift into a same calibration process, thereby greatly reducing calibration time and items, optimizing the calibration process and improving calibration efficiency on the basis of guaranteeing comprehensive calibration of various radar parameters.

[0029] The full-automatic calibration method can be used for full-automatic external calibration of the weather radar to be calibrated and can also be used for full-automatic internal calibration of the weather radar to be calibrated, and can meet the internal and external joint calibration requirements of the weather radar to be calibrated in actual application scenarios. In addition, the method can automatically compare and correct external calibration errors and internal calibration errors, further improves the calibration efficiency and avoids errors introduced by human operation. BRIEF DESCRIPTION OF DRAWINGS

[0030] FIG. 1 is a method flowchart of external calibration of a weather radar to be calibrated by using the full-automatic calibration method in an embodiment of the application.

[0031] FIG. 2 is a method flowchart of internal calibration of a weather radar to be calibrated by using the full-automatic calibration method in an embodiment of the application.

[0032] FIG. 3 is a hardware structure diagram for implementing the full-automatic calibration method in an embodiment of the application. Embodiment of the application

[0033] The specific embodiments of the application are further described below with reference to the accompanying drawings.

[0034] The application discloses a full-automatic calibration method of a weather radar, which includes the following steps, please refer to the flowcharts shown in FIG. 1 and FIG. 2:

[0035] Step 1: inject multiple groups of calibration differential signals into a receiver of a weather radar to be calibrated in sequence.

[0036] The injection power of at least two groups of calibration differential signals is different, the frequency offset of at least two groups of calibration differential signals is different, and the spectral width of at least two groups of calibration differential signals is different.

[0037] In addition, the change range of the injection power of the calibration differential signals injected into the receiver of the weather radar to be calibrated meets the fluctuation range requirement, for example, the change range of the injection power of the calibration differential signals is greater than 100 dB in practice.

[0038] Step 2, obtaining the intensity measured value, the speed measured value, the spectrum width measured value, the differential reflectivity factor measured value and the differential propagation phase shift measured value of the weather radar to be calibrated under each set of calibration differential signals.

[0039] Step 3, obtaining the calibration error of intensity according to the injection power of each set of calibration differential signals and the intensity measured value of the weather radar to be calibrated under the corresponding calibration differential signal, obtaining the calibration error of speed according to the frequency offset of each set of calibration differential signals and the speed measured value of the weather radar to be calibrated under the corresponding calibration differential signal, obtaining the calibration error of spectrum width according to the spectrum width of each set of calibration differential signals and the spectrum width measured value of the weather radar to be calibrated under the corresponding calibration differential signal, obtaining the calibration error of differential reflectivity factor and the calibration error of differential propagation phase shift according to the differential reflectivity factor measured value and the differential propagation phase shift measured value of the weather radar to be calibrated under the corresponding calibration differential signal.

[0040] In a conventional calibration test process, when intensity, speed, spectrum width, differential reflectivity factor and differential propagation phase shift need to be calibrated, a system needs to be built respectively to calibrate these different radar parameters. For example, the receiver of the weather radar to be calibrated needs to be injected with single signals with different injection powers to calibrate intensity. After the intensity calibration is completed, the receiver of the weather radar to be calibrated needs to be injected with single signals with different frequency offsets to calibrate speed. After the speed calibration is completed, the receiver of the weather radar to be calibrated needs to be injected with single signals with different spectrum widths to calibrate spectrum width. Then the receiver of the weather radar to be calibrated needs to be injected with differential signals to calibrate differential reflectivity factor and differential propagation phase shift. That is, the traditional calibration process needs to calibrate intensity, speed, spectrum width, differential reflectivity factor and differential propagation phase shift in turn, which results in a long calibration time when all these radar parameters need to be calibrated comprehensively. Currently, it takes one day or even more days to complete the calibration of all the above radar parameters of the weather radar to be calibrated.

[0041] However, the present application calibrates intensity, speed, spectrum width, differential reflectivity factor and differential propagation phase shift uniformly. Based on the calibration test of differential reflectivity factor and differential propagation phase shift, the injection power change required for intensity calibration is included in the calibration differential signal to complete the intensity calibration simultaneously, the frequency offset change required for speed calibration is included in the calibration differential signal to complete the speed calibration simultaneously, and the spectrum width change required for spectrum width calibration is included in the calibration differential signal to complete the speed calibration simultaneously. Since the injection power and the frequency offset are independent of each other, the above calibration process does not interfere with each other among intensity, speed, spectrum width, differential reflectivity factor and differential propagation phase shift.

[0042] Therefore, the calibration errors of all the radar parameters are obtained uniformly, which includes:

[0043] (1) Calculate the intensity theoretical value corresponding to the injection power of each set of calibration differential signals, and calculate the error between the intensity measured value and the intensity theoretical value of the to-be-calibrated weather radar under the corresponding calibration differential signal to obtain the intensity error corresponding to a set of calibration differential signals. Because there are at least two sets of calibration differential signals with different injection powers, and more different injection powers are included in actual implementation, it is equivalent to achieving the effect of intensity testing under different injection powers, so the root mean square error of the intensity error corresponding to each set of calibration differential signals can be obtained. The calibration error of the intensity.

[0044] (2) Calculate the velocity theoretical value corresponding to the frequency offset of each set of calibration differential signals, and calculate the error between the velocity measured value and the velocity theoretical value of the to-be-calibrated weather radar under the corresponding calibration differential signal to obtain the velocity error corresponding to a set of calibration differential signals. Because there are at least two sets of calibration differential signals with different frequency offsets, and more different frequency offsets are included in actual implementation, it is equivalent to achieving the effect of velocity testing under different frequency offsets, so the root mean square error of the velocity error corresponding to each set of calibration differential signals is obtained. The calibration error of the velocity.

[0045] (3) Calculate the error between the spectrum width measured value of the to-be-calibrated weather radar under the corresponding internal calibration differential signal and the corresponding spectrum width theoretical value to obtain the spectrum width error corresponding to a set of internal calibration differential signals. The root mean square error of the spectrum width error corresponding to each set of internal calibration differential signals is obtained. The internal calibration error of the spectrum width.

[0046] (4) Calculate the root mean square error of the differential reflectivity factor measured value of the to-be-calibrated weather radar under each set of calibration differential signals to obtain the calibration error of the differential reflectivity factor.

[0047] (5) Calculate the root mean square error of the differential propagation phase shift measured value of the to-be-calibrated weather radar under each set of calibration differential signals to obtain the calibration error of the differential propagation phase shift.

[0048] The above-mentioned full-automatic calibration method provided by the application can be used for external calibration of the to-be-calibrated weather radar, and can also be used for internal calibration of the to-be-calibrated weather radar. In actual implementation, the to-be-calibrated weather radar needs to be calibrated externally according to the full-automatic calibration method of the application, and the to-be-calibrated weather radar also needs to be calibrated internally according to the full-automatic calibration method of the application. The application scenarios of the two parts are slightly different.

[0049] I. Use the full-automatic calibration method to realize external calibration of the to-be-calibrated weather radar

[0050] The automatic calibration method is implemented based on the hardware system shown in FIG. 3. The automatic calibration method needs to use a calibration host, an external signal source, a power divider, and necessary connection cables. The calibration host is connected to the external signal source. The output end of the external signal source is connected to the input end of the power divider. The two output ends of the power divider are connected to the related test ports of the weather radar to be calibrated to connect to the receiver inside the weather radar to be calibrated. The calibration host is also connected to the weather radar to be calibrated for information interaction.

[0051] Based on the hardware architecture of FIG. 3, after the cable connection between the devices is completed, the calibration host can perform automatic external calibration on the weather radar to be calibrated according to the automatic calibration method of the present application. Step 1 is specifically implemented by using the external signal source to output a plurality of different output signals. Each output signal forms a group of calibration differential signals by outputting two equal calibration signals through the power divider and injecting the calibration differential signals into the receiver of the weather radar to be calibrated, so as to correspondingly obtain the calibration error of each radar parameter, which is recorded as an external calibration error to distinguish from internal calibration. Then, the calibration host can automatically perform external calibration according to the measured value of the weather radar to be calibrated. FIG. 1 is a method flowchart of external calibration using the automatic calibration method.

[0052] In addition, the automatic calibration method of the present application can also calibrate the coupled power. As shown in FIG. 3, the hardware system further includes a power meter. The input end of the power meter is connected to the power coupling port of the weather radar to be calibrated. The output end of the power meter is connected to the calibration host. The automatic calibration method executed by the calibration host further includes:

[0053] controlling the transmitter of the weather radar to be calibrated to transmit according to a plurality of different working pulse widths, and using the power meter to measure the power measured value of the power coupling port of the weather radar to be calibrated under each working pulse width as the internal calibration reference of the working pulse width.

[0054] II. Internal calibration of the weather radar to be calibrated using the automatic calibration method

[0055] The method also uses the calibration host in FIG. 3 to perform automatic internal calibration on the weather radar to be calibrated according to the automatic calibration method of the present application, which includes controlling the internal calibration source built-in the weather radar to be calibrated to generate a plurality of groups of calibration differential signals and inject the calibration differential signals into the receiver of the weather radar to be calibrated, so as to correspondingly obtain the calibration error of each radar parameter, which is recorded as an internal calibration error to distinguish from external calibration. FIG. 2 is a method flowchart of external calibration using the automatic calibration method.

[0056] In addition, the internal calibration scene can also be obtained in the external calibration scene as the internal calibration reference for error calculation of internal calibration and external calibration, and the full-automatic calibration method executed by the calibration host further comprises: controlling the transmitter of the meteorological radar to be calibrated to emit according to a plurality of groups of working pulse widths, and determining the internal power measurement value calculated by the meteorological radar to be calibrated under each group of working pulse widths, calculating the power error between the internal power measurement value under each working pulse width and the internal calibration reference under the working pulse width, and calculating the root mean square error of the power error of all working pulse widths to obtain the internal and external calibration error of the power.

[0057] In actual application process, the meteorological radar to be calibrated is operated according to the predetermined period and the external calibration error of each radar parameter is obtained according to the full-automatic calibration method of the present application. In the working process of the meteorological radar to be calibrated, the internal calibration source is used to perform internal calibration operation on the meteorological radar to be calibrated according to the full-automatic calibration method of the present application in the detection gap (in each body scan interval) of the meteorological radar to be calibrated, and the internal calibration error of each radar parameter is obtained.

[0058] The calibration host will also automatically compare the internal calibration error and the external calibration error, and when the deviation of the internal calibration error of each radar parameter and the corresponding external calibration error of the radar parameter exceeds the deviation threshold, the internal calibration source of the meteorological radar to be calibrated is corrected until the deviation of the internal calibration error of the radar parameter and the corresponding external calibration error is within the deviation threshold, thereby realizing automatic correction of the internal and external calibration errors, improving the correction efficiency and avoiding operation errors introduced by manual correction.

Claims

1. A fully automatic calibration method for a weather radar, characterized in that, The full-automatic calibration method comprises: Injecting multiple sets of calibration differential signals into the receiver of the weather radar to be calibrated in sequence, wherein the injection power of at least two sets of calibration differential signals is different, the frequency offset of at least two sets of calibration differential signals is different, and the spectrum width of at least two sets of calibration differential signals is different; Obtaining the intensity measured value, the speed measured value, the spectrum width measured value, the differential reflectivity factor measured value and the differential propagation phase shift measured value of the weather radar to be calibrated under each set of calibration differential signals; Obtaining the calibration error of intensity according to the injection power of each set of calibration differential signals and the intensity measured value of the weather radar to be calibrated under the corresponding calibration differential signal, obtaining the calibration error of speed according to the frequency offset of each set of calibration differential signals and the speed measured value of the weather radar to be calibrated under the corresponding calibration differential signal, obtaining the calibration error of spectrum width according to the spectrum width of each set of calibration differential signals and the spectrum width measured value of the weather radar to be calibrated under the corresponding calibration differential signal, and obtaining the calibration error of differential reflectivity factor and the calibration error of differential propagation phase shift according to the differential reflectivity factor measured value and the differential propagation phase shift measured value of the weather radar to be calibrated under the corresponding calibration differential signal.

2. The fully automatic calibration method according to claim 1, characterized in that, Injecting multiple sets of calibration differential signals into the receiver of the weather radar to be calibrated in sequence comprises: Outputting a plurality of different output signals by using an external signal source, and outputting two equal calibration signals from each output signal via a power divider to form a set of calibration differential signals and inject the set of calibration differential signals into the receiver of the weather radar to be calibrated, so as to obtain the external calibration error of each radar parameter.

3. The fully automatic calibration method according to claim 2, characterized in that, The full-automatic calibration method further comprises: Controlling the transmitter of the weather radar to be calibrated to transmit according to a plurality of different working pulse widths, and measuring the power measured value of the power coupling port of the weather radar to be calibrated under each working pulse width by using a power meter as the in-machine calibration reference under the working pulse width.

4. The fully automatic calibration method according to claim 3, characterized in that, Injecting multiple sets of calibration differential signals into the receiver of the weather radar to be calibrated in sequence comprises: Controlling the internal calibration source built in the weather radar to be calibrated to generate a plurality of sets of calibration differential signals and inject the sets of calibration differential signals into the receiver of the weather radar to be calibrated, so as to obtain the internal calibration error of each radar parameter.

5. The fully automatic calibration method according to claim 4, characterized in that, The full-automatic calibration method further comprises: Controlling the transmitter of the weather radar to be calibrated to transmit according to a plurality of sets of working pulse widths, and determining the in-machine power measurement value calculated by the weather radar to be calibrated under each set of working pulse width, calculating the power error between the in-machine power measurement value under each working pulse width and the in-machine calibration reference under the working pulse width, and calculating the root mean square error of the power errors of all working pulse widths to obtain the internal and external calibration error of power.

6. The fully automatic calibration method according to claim 4, characterized in that, The full-automatic calibration method further comprises: Performing internal calibration operation on the weather radar to be calibrated by using the internal calibration source during the detection gap of the weather radar to be calibrated, and obtaining the internal calibration error of each radar parameter; When the deviation between the internal calibration error of each radar parameter and the external calibration error of the corresponding radar parameter exceeds the deviation threshold, correcting the internal calibration source of the weather radar to be calibrated until the deviation between the internal calibration error of the radar parameter and the corresponding external calibration error is within the deviation threshold.

7. The fully automated calibration method of claim 1, wherein, Obtaining the calibration error of each radar parameter comprises: calculating a strength error corresponding to each set of calibration differential signals by calculating the error between the measured value of the strength of the weather radar to be calibrated under the corresponding calibration differential signal and the theoretical value of the strength, and calculating a calibration error of the strength by calculating the root mean square error of the strength errors corresponding to each set of calibration differential signals; calculating a velocity error corresponding to each set of calibration differential signals by calculating the error between the measured value of the velocity of the weather radar to be calibrated under the corresponding calibration differential signal and the theoretical value of the velocity, and calculating a calibration error of the velocity by calculating the root mean square error of the velocity errors corresponding to each set of calibration differential signals; calculating a spectrum width error corresponding to each set of calibration differential signals by calculating the error between the measured value of the spectrum width of the weather radar to be calibrated under the corresponding calibration differential signal and the theoretical value of the spectrum width, and calculating a calibration error of the spectrum width by calculating the root mean square error of the spectrum width errors corresponding to each set of calibration differential signals; calculating a calibration error of the differential reflectivity factor by calculating the root mean square error of the measured values of the differential reflectivity factor of the weather radar to be calibrated under each set of calibration differential signals; calculating a calibration error of the differential propagation phase shift by calculating the root mean square error of the measured values of the differential propagation phase shift of the weather radar to be calibrated under each set of calibration differential signals.

8. The full-automatic calibration method according to claim 1, wherein the variation range of the injection power of the calibration differential signal injected into the receiver of the weather radar to be calibrated meets the fluctuation range requirement. ​

Images