A far-field single-distance library reflectivity factor simulation method

Abstract

The present invention relates to a far-field single-range bin reflectivity factor simulation method, belonging to the field of radio. The simulation method comprises: S1, respectively obtaining a radar signal length #imgabs0#, a signal space width θ, and a signal space height #imgabs1#; S2, transmitting a specific pulse signal to a radar via an echo simulation device, which is received and analyzed by the radar, and combining the three data obtained in S1 to calculate the expected single-range bin target reflectivity factor. The present invention significantly reduces the dependence of radar reflectivity factor calibration on radar parameter accuracy, increases the reliability of radar emissivity calibration, and avoids the aliasing of far-field environmental echoes and simulated signal echoes, which can cause indistinguishability.

Description

Technical Field

[0001] The present invention relates to the field of radio, and in particular to a far-field single-distance library reflectivity factor simulation method. Background Art

[0002] Currently, my country's weather radar network coverage has reached over 90%, and the availability and consistency of weather radar detection data are becoming increasingly important. Differences in calibration accuracy among different radars significantly impact the networked observation of radar reflectivity factor products. Traditional calibration methods also suffer from the limitation of not including full-link calibration testing of passive links such as radar feeders, antennas, and radomes. Furthermore, current far-field target reflectivity factor simulation methods require accurate knowledge of radar hardware parameters to calculate radar constants. This method can lead to errors in target reflectivity factor simulation results due to inaccurate radar hardware parameters. Therefore, an objective long-range target intensity simulation method is needed to perform far-field simulation verification of radar reflectivity factors. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a far-field single-distance library reflectivity factor simulation method to solve the shortcomings of the prior art.

[0004] The object of the present invention is achieved by the following technical solution: a far-field single-distance library reflectivity factor simulation method, the simulation method comprising:

[0005] S1. Get the radar signal length respectively , signal space width and signal space height ;

[0006] S2: A specific pulse signal is transmitted to the radar through the echo simulation device, and the radar receives and analyzes the pulse signal. The expected single-range library target reflectivity factor is calculated by combining the three data obtained in S1.

[0007] The signal length The acquisition includes:

[0008] When the radar aligns the beam direction with the far-field echo simulation device, it turns on the radar transmission function and radiates the pulse signal to the space normally through the antenna. The echo simulation device receives the pulse signal and samples the signal through the built-in digital sampling board. The I / Q information of the sampled signal is used to calculate the signal using the formula , calculate the received signal power , through high-speed continuous sampling by the digital system, the amplitude fluctuation of the signal within the pulse period is restored, and the length of the radar pulse signal is calculated and restored. .

[0009] The signal space width The acquisition includes:

[0010] The radar aligns its beam direction with the far-field echo simulator, turns on the radar transmission function, and radiates the pulse signal normally into space through the radar antenna. The echo simulator receives the pulse signal and samples it with the built-in digital sampling board to obtain signal amplitude information.

[0011] Then slowly rotate the radar transmitting antenna counterclockwise by N times the theoretical beam width of the antenna to cover the relative position angle of the echo simulation device, and then rotate it clockwise by N times the theoretical beam width of the antenna to cover the relative position angle of the echo simulation device. The echo simulation device continuously samples the signal radiated by the radar to the space, and draws a curve of the sampling amplitude changing with the rotation angle of the radar antenna. The horizontal axis is the rotation angle of the radar antenna, and the vertical axis is the sampling amplitude. Taking the maximum sampling amplitude drop of 3dB as the standard, the horizontal axis difference of the curve corresponding to the amplitude drop of 3dB is calculated, which is the spatial width of the radar transmitting signal. .

[0012] The signal space height The acquisition includes:

[0013] The radar aligns its beam direction with the far-field echo simulator, turns on the radar transmission function, and radiates the pulse signal normally into space through the radar antenna. The echo simulator receives the signal and samples it with the built-in digital sampling board to obtain signal amplitude information.

[0014] Then slowly rotate the radar transmitting antenna, rotate it vertically upward by N times the theoretical beam width of the antenna, covering the relative position angle of the echo simulation device, and then rotate it vertically downward by N times the theoretical beam width of the antenna, covering the relative position angle of the echo simulation device. The echo simulation device continuously samples the signal radiated by the radar to the space, and draws a curve of the sampling amplitude changing with the rotation angle of the radar antenna. The horizontal axis is the rotation angle of the radar antenna, and the vertical axis is the sampling amplitude. Taking the maximum sampling amplitude drop of 3dB as the standard, calculate the horizontal axis difference of the curve corresponding to the amplitude drop of 3dB, which is the spatial height of the radar transmitting signal. .

[0015] The expected single-range library target reflectivity factor calculated by combining the three data obtained in S1 includes:

[0016] Assume that the radar transmission power is P t , the received signal power of the far-field echo simulation device is P r ’ , the far-field echo simulation device transmit power is P t ’ , the radar received signal power is P rThe expected simulated single range library target position distance is L, the echo simulation device is at a radial distance from the radar R, and the electromagnetic wave space distance attenuation rate is L at ;

[0017] According to the Friis transmission formula, the theoretical receiving power of the far-field echo simulation device is calculated respectively: , and the radar receiving far-field echo simulation device transmitting signal power for and ;

[0018] According to the weather radar reflectivity factor equation, the current radar receiving power reflectivity factor is calculated as follows: , and then get , is the radar antenna gain, is the antenna gain of the far-field echo simulation device, λ is the wavelength of the working electromagnetic wave, Z is the expected value of the simulated target reflectivity factor, is the reference value of the target reflectivity factor;

[0019] If P t ’ =P r ’ , R ’ =R, then 、 and , To simulate the target distance of a single reservoir;

[0020] Introduction , as the reference value of the single-range library target reflectivity factor, we get , and then through the formula The expected single-range library target reflectivity factor is calculated.

[0021] Assume that the time required for the echo simulation device to process the signal is , the electromagnetic wave space transmission speed is c, and the echo simulation device delay time is , if the echo simulation device does not perform any delay processing on the signal, that is When the echo simulation device is expected to simulate the target position distance L of the single range library, .

[0022] Only when the expected simulated position distance of the single-range library target is greater than the expected simulated single-range library target position distance L, the echo simulation device processes the signal through internal delay to realize the single-range library target position distance simulation.

[0023] The present invention has the following advantages: a far-field single-range library reflectivity factor simulation method, which greatly reduces the dependence of radar reflectivity factor calibration on radar parameter accuracy and increases the credibility of radar emissivity calibration; avoids the aliasing of far-field environmental echoes and simulated signal echoes, which causes indistinguishability. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the simulation of the single-distance library target reflectivity factor of the present invention;

[0025] Figure 2 This is a schematic diagram of the single-distance library position simulation of the present invention. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the detailed description of the embodiments of the present application provided below in conjunction with the drawings is not intended to limit the scope of protection of the present application for which protection is claimed, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of the present application. The present invention is further described below in conjunction with the drawings.

[0027] To address the problem of large errors in the reflectivity factor of radar detection targets due to calibration errors and low hardware link parameter accuracy in different weather radars, the present invention designs a single-range library reflectivity factor simulation method based on a far-field signal sampling and generation device. The method is used to test the reflectivity factor accuracy of the target radar in the far field. By simulating a single-range library target, the difference between the radar detection result and the expected result is compared to verify the detection accuracy of the target radar reflectivity factor.

[0028] Specifically include the following:

[0029] Get radar signal length (Pulse width): When the radar aligns the beam direction with the far-field echo simulator, it turns on the radar transmission function and radiates the pulse signal into space normally through the antenna. The echo simulator receives the signal and the built-in digital sampling board samples the signal. Based on the I / Q information of the sampled signal, the formula , calculate the received signal power P r ’ Through high-speed continuous sampling of the digital system, the amplitude fluctuation of the signal within the pulse period can be restored, and the length of the radar pulse signal can be calculated and restored. .

[0030] Get the signal space width (Beam width in azimuth): The radar aligns the beam direction with the far-field echo simulator, turns on the radar transmission function, and radiates the pulse signal normally into space through the radar antenna. The echo simulator receives the signal, and the built-in digital sampling board samples the signal to obtain the signal amplitude information. Then slowly rotate the radar transmitting antenna counterclockwise by 10 times the theoretical beam width of the antenna to cover the relative position angle of the echo simulator, and then rotate clockwise by 10 times the theoretical beam width of the antenna to cover the relative position angle of the echo simulator. The echo simulator continuously samples the signal radiated by the radar into space, and draws a curve showing the sampling amplitude changing with the rotation angle of the radar antenna. The horizontal axis is the rotation angle of the radar antenna, and the vertical axis is the sampling amplitude. Taking the maximum sampling amplitude drop of 3dB as the standard, the horizontal axis difference of the curve corresponding to the amplitude drop of 3dB is calculated, which is the spatial width of the radar transmission signal. .

[0031] Get the signal space height (Beam width in elevation): The radar aligns the beam direction with the far-field echo simulator, turns on the radar transmission function, and radiates the pulse signal normally into space through the radar antenna. The echo simulator receives the signal, and the built-in digital sampling board samples the signal to obtain the signal amplitude information. Then, the radar transmitting antenna is slowly rotated, and the vertical upward rotation is 10 times the theoretical beam width of the antenna to cover the relative position angle of the echo simulator. Then, the vertical downward rotation is 10 times the theoretical beam width of the antenna to cover the relative position angle of the echo simulator. The echo simulator continuously samples the signal radiated by the radar into space, and draws a curve showing the sampling amplitude changing with the rotation angle of the radar antenna. The horizontal axis is the rotation angle of the radar antenna, and the vertical axis is the sampling amplitude. Taking the maximum sampling amplitude drop of 3dB as the standard, the horizontal axis difference of the curve corresponding to the amplitude drop of 3dB is calculated, which is the spatial height of the radar transmitting signal. .

[0032] Radars that use a common transmit and receive antenna typically exhibit reciprocal transmit and receive performance. This allows for measurement by radiating a signal using an echo simulator and sampling it using a radar receiver. For situations where the transmitted and received signals have different spatial scales, the smaller result is typically used to assign the signal spatial scale after performing the reciprocal measurement.

[0033] The far-field echo simulation device can already obtain the signal P r ’ , , and , which is the three-dimensional scale represented by the signal in space. The far-field single-range library target reflectivity factor simulation uses an echo simulator to transmit a specific pulse signal to the radar, which then receives and analyzes the signal.

[0034] Furthermore, the calculation method for simulating the reflectivity factor of the far-field single-range library target is evaluated by combining the echo reflectivity factor calculation formula and the Friis transmission formula, specifically including the following:

[0035] like Figure 1 As shown, let the radar transmission power be P t , in mW, the far-field echo simulation device receives the signal power P r ’ , in mW, is the radar antenna gain, is the antenna gain of the far-field echo simulation device, and the transmission power of the far-field echo simulation device is P t ’ , in mW, the radar receiving signal power is P r , unit is mW, the expected simulated target distance is L, unit is m, the radial distance of the echo simulation device from the radar is R, unit is m, L at It is the attenuation rate of electromagnetic waves over space distance, and its unit is dB / km.

[0036] According to the Friis transmission formula, the transmission power of the far-field echo simulation device can be calculated separately , and radar received signal power .

[0037] ,

[0038] ,

[0039] According to the weather radar reflectivity factor equation, the current radar receiving power reflectivity factor can be calculated. is the wavelength of the working electromagnetic wave, To simulate the target distance of a single library.

[0040] ,

[0041] Z is the expected value of the simulated target reflectivity factor, in dBZ. Substituting the above Friis formula into the weather radar reflectivity factor equation, we get:

[0042] ,

[0043] If P t ’ =P r ’ , R ’=R, then:

[0044] ,

[0045] ,

[0046] ,

[0047] ,

[0048] Introduction , is the reference value of the single-range library target reflectivity factor, is the target reflectivity factor reference value, and we get:

[0049] ,

[0050] Simulate the device's transmit power based on the far-field echo and far-field echo simulator received power , combined with the meteorological radar reflectivity factor measurement principle and distance correction method, the transmission power is:

[0051] ,

[0052] The unit of logarithmic power in the formula is dBm. The above formula can be used to calculate the expected single-range library target reflectivity factor. During simulation, the echo simulation device needs to output the pulse transmission power.

[0053] Reference value The calculation needs to consider the radar signal length and signal space width and space height , which can be obtained by the far-field test of the echo simulator. When simulating a single distance library, the output power of the echo simulator must also be calculated based on the signal power P received by the echo simulator. r ’ , can also be measured by the echo simulation device itself.

[0054] Considering that in actual use, the location where the echo simulator is installed will also reflect radar signals, the signal emitted by the echo simulator may be mixed with the echoes of certain nearby ground objects and cannot be distinguished. Therefore, when simulating and calculating the reflectivity factor of a single distance library, the echo simulator also needs to change and accurately control the location of the single distance library to distinguish the echo reflectivity factor of the simulated distance library from that of the device's installation location.

[0055] like Figure 2As shown in the figure, the principle of radar single-range bin position simulation is to quantitatively delay the radar echo signal. Specifically, after receiving the pulse signal transmitted by the radar, the echo simulation device digitally samples and stores the signal. Using the internal timing of the FPGA, the signal is delayed before being replayed as an analog signal and sent back to the radar, completing the single-range bin position simulation process. The delay time of the signal playback within the FPGA determines the position of the target simulated in the single-range bin.

[0056] As the single-range library position simulation process demonstrates, position simulation inevitably has a blind spot, or minimum simulated position distance. Below this distance, even if a target is outside the radar blind spot, the echo simulator cannot simulate it. The blind spot is determined by two factors: the relative radial distance between the echo simulator and the radar, and the time required for the echo simulator's internal signal processing.

[0057] Assume that the distance of the target position in the single range library expected to be simulated by the echo simulator is L, the radial distance between the echo simulator and the radar is R, and the time required for the signal processing flow inside the echo simulator is , the electromagnetic wave space transmission speed is c, and the echo simulation device delay time is If the echo simulation device does not perform any delay processing on the signal, that is, When , the echo simulation device is expected to simulate the single range library target position distance L as:

[0058] ,

[0059] At this point, L is the echo simulator's blind spot for simulating single-range target locations, representing the minimum distance it can simulate. Only when the desired simulated single-range target location is greater than this distance can the echo simulator process the signal through internal signal delay, effectively simulating the single-range target location.

[0060] The foregoing description is merely a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein and should not be construed as excluding other embodiments. Rather, the present invention is capable of various other combinations, modifications, and improvements, and is capable of modifications within the scope of the concepts described herein, through the above teachings, or through techniques or knowledge in the relevant fields. Modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention are intended to be within the scope of the appended claims.

Claims

1. A far-field single-distance library reflectivity factor simulation method, characterized by: The simulation method comprises: S1. Get the radar signal length respectively , signal space width and signal space height ; S2: The radar transmits a specific pulse signal through the echo simulation device, which is then received and analyzed by the radar. The expected single-range target reflectivity factor is calculated based on the three data obtained in S1. The expected single-range library target reflectivity factor calculated by combining the three data obtained in S1 includes: Assume that the radar transmission power is P t , the received signal power of the far-field echo simulation device is P r ’ , the far-field echo simulation device transmit power is P t ’ , the radar received signal power is P r The expected simulated single range library target position distance is L, the echo simulation device is at a radial distance from the radar R, and the electromagnetic wave space distance attenuation rate is L at ; According to the Friis transmission formula, the received signal power of the far-field echo simulation device is calculated respectively , and radar received signal power for and ; According to the weather radar reflectivity factor equation, the current radar receiving power reflectivity factor is calculated as follows: , Substituting the above Friis formula into the weather radar reflectivity factor equation, we get: ， If P t ’ =P r ’ , R ’ =R, then , , , , is the radar antenna gain, is the antenna gain of the far-field echo simulation device, λ is the wavelength of the working electromagnetic wave, Z is the reflectivity factor of the expected single-range library target, is the target reflectivity factor reference value, To simulate the target distance of a single reservoir; Introduction , as the reference value of the single-range library target reflectivity factor, we get , and then through the formula The expected single-range library target reflectivity factor is calculated.

2. A far-field single-distance reservoir reflectivity factor simulation method according to claim 1, characterized in that: The signal length The acquisition includes: When the radar aligns the beam direction with the far-field echo simulation device, it turns on the radar transmission function and radiates the pulse signal to the space normally through the antenna. The echo simulation device receives the pulse signal and samples the signal through the built-in digital sampling board. The I / Q information of the sampled signal is used to calculate the signal using the formula , calculate the received signal power , through high-speed continuous sampling by the digital system, the amplitude fluctuation of the signal within the pulse period is restored, and the length of the radar pulse signal is calculated and restored. .

3. The far-field single-distance reservoir reflectivity factor simulation method according to claim 1, characterized in that: The signal space width The acquisition includes: The radar aligns its beam direction with the far-field echo simulator, turns on the radar transmission function, and radiates the pulse signal normally into space through the radar antenna. The echo simulator receives the pulse signal and samples it with the built-in digital sampling board to obtain signal amplitude information. Then slowly rotate the radar transmitting antenna counterclockwise by N times the theoretical beam width of the antenna to cover the relative position angle of the echo simulation device, and then rotate it clockwise by N times the theoretical beam width of the antenna to cover the relative position angle of the echo simulation device. The echo simulation device continuously samples the signal radiated by the radar to the space, and draws a curve of the sampling amplitude changing with the rotation angle of the radar antenna. The horizontal axis is the rotation angle of the radar antenna, and the vertical axis is the sampling amplitude. Taking the maximum sampling amplitude drop of 3dB as the standard, the horizontal axis difference of the curve corresponding to the amplitude drop of 3dB is calculated, which is the spatial width of the radar transmitting signal. .

4. The far-field single-distance library reflectivity factor simulation method according to claim 1, characterized in that: The signal space height The acquisition includes: The radar aligns its beam direction with the far-field echo simulator, turns on the radar transmission function, and radiates the pulse signal normally into space through the radar antenna. The echo simulator receives the signal and samples it with the built-in digital sampling board to obtain signal amplitude information. Then slowly rotate the radar transmitting antenna, rotate it vertically upward by N times the theoretical beam width of the antenna, covering the relative position angle of the echo simulation device, and then rotate it vertically downward by N times the theoretical beam width of the antenna, covering the relative position angle of the echo simulation device. The echo simulation device continuously samples the signal radiated by the radar to the space, and draws a curve of the sampling amplitude changing with the rotation angle of the radar antenna. The horizontal axis is the rotation angle of the radar antenna, and the vertical axis is the sampling amplitude. Taking the maximum sampling amplitude drop of 3dB as the standard, calculate the horizontal axis difference of the curve corresponding to the amplitude drop of 3dB, which is the spatial height of the radar transmitting signal. .

5. The far-field single-distance reservoir reflectivity factor simulation method according to claim 1, characterized in that: Assume that the time required for the echo simulation device to process the signal is , the electromagnetic wave space transmission speed is c, and the echo simulation device delay time is , if the echo simulation device does not perform any delay processing on the signal, that is When the echo simulation device is expected to simulate the target position distance L of the single range library, .

6. The far-field single-distance reservoir reflectivity factor simulation method according to claim 1, characterized in that: Only when the expected simulated position distance of the single-range library target is greater than the expected simulated single-range library target position distance L, the echo simulation device processes the signal through internal delay to realize the single-range library target position distance simulation.

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