Lightning signal simulation system based on VHF frequency band

Abstract

The embodiment of the invention provides a lightning signal simulation system based on a VHF frequency band. The system is applied to the technical field of lightning monitoring and comprises an upper computer, a lightning signal simulation device and a ground receiver. The upper computer is in wireless communication with the thunder and lightning signal simulation device and is used for sending a configuration command to the thunder and lightning signal simulation device; the thunder and lightning signal simulation device analyzes and processes the configuration command, generates a thunder and lightning simulation signal and radiates the thunder and lightning simulation signal to the ground receiver; the lightning signal simulation device comprises a power supply, a data transmitter, a control panel, a power amplifier and an antenna; the data transmitter is connected with the upper computer, receives a configuration command of the upper computer through the data transmitter and transmits the configuration command to the control panel for processing to obtain a lightning analog signal, state information and output information; and the radiation is transmitted to the ground receiver and is transmitted back to the upper computer. The system has the characteristics of high performance and high precision, can generate an electromagnetic field similar to a real lightning signal, and simulates various parameters when lightning occurs.

Description

Technical Field

[0001] The present disclosure relates to the technical field of lightning monitoring, and in particular to a lightning signal simulation system based on a VHF frequency band. Background Art

[0002] Lightning is a common natural phenomenon in which a large number of positive and negative electrons gather and saturate in the atmosphere and then release instantly. It releases huge energy during the occurrence process and has the characteristics of large current, high voltage, and strong electromagnetic radiation. Lightning prevention has always been a key focus in related fields.

[0003] At present, almost all developed countries and regions have established national or regional lightning monitoring networks. With the increasing investment in lightning disaster and detection research in my country, the corresponding lightning monitoring and forecasting systems have been gradually put into operation. However, there has been no significant progress in the field of lightning signal simulation technology. Therefore, it is very necessary to provide a simulation system that can simulate and receive lightning signals. Summary of the invention

[0004] The present invention provides a lightning signal simulation system based on the VHF frequency band, which solves the technical problem that the existing lightning monitoring technology cannot realize lightning signal simulation.

[0005] According to a first aspect of the present disclosure, there is provided a lightning signal simulation system based on a VHF frequency band, comprising a host computer, a lightning signal simulation device and a ground receiver;

[0006] The host computer communicates wirelessly with the lightning signal simulation device and is used to send a configuration command to the lightning signal simulation device;

[0007] The lightning signal simulation device analyzes and processes the configuration command to generate a lightning simulation signal which is then transmitted back by the ground receiver for reception;

[0008] The lightning signal simulation device includes a power supply, a data transmitter, a control board, a power amplifier, and an antenna; the data transmitter is connected to the host computer, receives the configuration command of the host computer through the data transmitter and transmits it to the control board for processing to obtain the lightning simulation signal and the status information and output information of the lightning signal simulation device; the power amplifier amplifies the lightning simulation signal and radiates it to the ground receiver through the antenna, and the status information and output information are transmitted back to the host computer, and the power supply provides power for the control board and the power amplifier.

[0009] According to the aspects described above and any possible implementation manner, there is further provided an implementation manner, wherein the state information and output information include time data, position data, signal configuration data, and AD data.

[0010] According to the above aspects and any possible implementation manner, an implementation manner is further provided, in which the amplified power of the power amplifier is calculated as follows:

[0011] Los=P-Sen+Gr+Gt (1)

[0012] Among them, Los is the propagation loss, P is the power amplifier transmission power, Sen is the receiving sensitivity, Gr is the receiving antenna gain, and Gt is the transmitting antenna gain.

[0013] According to the above aspects and any possible implementation manner, an implementation manner is further provided, wherein the antenna field strength includes near-field strength and far-field strength, specifically:

[0014] The calculation method of near-field strength is:

[0015] Lf 1 =32.44+20lgl+20lgf 0 (2)

[0016] Lf 2 =32.44+20lgl+20lgf 0 -3 (3)

[0017]

[0018]

[0019] Among them, Lfs 1 is the loss value when there is no near-field antenna, Lfs 2 is the loss value when there is a near-field antenna, f 0 is the initial frequency, P T is power, P p1 is the near field strength when there is no near field antenna, P p2 is the near-field strength when there is a near-field antenna;

[0020] The far-zone field strength is calculated as:

[0021]

[0022] Where d is the distance between the transmitter and the receiver, f is megahertz, dBi is the antenna increment,

[0023] Gr (dBi) = 101g (power density of the transmitting antenna toward the receiving end / power of an isotropic transmitting antenna with the same power in the same direction).

[0024] According to the above aspects and any possible implementation, an implementation is further provided, wherein the control board includes a Beidou module, an MCU module, a signal generation module, a radio frequency switch module, a detection module, an FPGA module, and a communication module;

[0025] The communication module is connected to the MCU module to realize data interaction between the host computer and the MCU module;

[0026] The Beidou module is connected to the MCU module and is used to collect time and location information and transmit it to the MCU module;

[0027] The signal generating module is connected to the MCU module and is used to generate a lightning simulation signal;

[0028] The RF switch module is connected to the signal generation module to control whether the analog signal is output. The RF switch module is also connected to the power amplifier to output a signal of a specified window time and amplify the signal.

[0029] The MCU module receives the transmission data from the Beidou module, the communication module and the detection module respectively, and controls the signal generation module to generate a lightning simulation signal by parsing the command data from the communication module.

[0030] According to the above aspects and any possible implementation, an implementation is further provided, wherein the Beidou module adopts the TAU3101 Beidou GPS timing receiving module, which can receive the Beidou satellite B1 frequency civil code signal and the GPS satellite L1 frequency C / A code signal;

[0031] The RF switch module adopts HMC849ALP4CE chip;

[0032] The MCU module adopts the STM32F103RCT6 chip, which can realize the module control function and receive the data sent back by the module;

[0033] The signal generation module uses the MAX2870ETJ+ chip.

[0034] According to the above aspects and any possible implementation manner, an implementation manner is further provided, wherein the process of generating a signal by the signal generating module is:

[0035]

[0036] Among them, f REF Indicates the external reference clock input frequency. The reference clock input frequency of the VHF lightning signal simulator is 25MHz. DBR is set to bit 25 of register 2. REFInput frequency multiplication mode 0 or 1; RDIV2 is register 2 bit 24 setting f REF The 2-division mode is 0 or 1; R is the programmable reference clock counter value at bit 10 of register 2, which is 1 to 1023;

[0037]

[0038] Where N is the value of the 16-bit counter, which is 16 to 65535; M is the fraction modulus, which is 2 to 4095; F is the divisor of the fraction, which is 0 to MOD-1; DIVA is the RF output divider, which is set to 0 to 7; FB is the feedback mode of the integrated voltage swing controller, f vco is the fundamental frequency voltage, f RFOUA The frequency at which the signal is generated for the chip.

[0039] According to the above aspects and any possible implementation, an implementation is further provided, wherein the FPGA module is connected to the Beidou module, the MCU module and the RF switch module respectively, and is used to analyze the data of the Beidou module and the MCU module and send a switch instruction to the RF switch module;

[0040] The detection module is connected to the RF switch module and the MCU module respectively, and is used to detect the RF power of the lightning simulation signal of the RF switch module, convert it into a measurable voltage value, and transmit it to the MCU module.

[0041] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the ground receiver comprises a lightning identification module, and the lightning identification module comprises a preprocessor, a clock circuit, a time-stamp signal generator, a lightning identification unit and a storage unit;

[0042] The preprocessor is connected to the lightning identification unit to implement input and identification of the lightning simulation signal;

[0043] The time-stamp signal generator is connected to the preprocessor and is used to identify and determine the signal reception time;

[0044] The clock circuit is connected to the time-stamp signal generator, the preprocessor and the lightning identification unit, and is used to provide and transmit a clock signal;

[0045] The lightning identification unit is used to identify the lightning signal processed by the preprocessor and determine whether it is a lightning simulation signal of the lightning signal simulation device;

[0046] The storage unit is connected to the lightning identification unit, and the judgment result obtained by the lightning identification unit is stored in the storage unit for standby use.

[0047] Compared with the prior art, the present invention has the following beneficial effects:

[0048] (1) The present invention uses a UAV to fly a certain trajectory, and the ground network lightning equipment receives the radio frequency pulses emitted by the lightning signal simulation device. Through the GNSS positioning data and time data carried by the UAV and the network positioning after the lightning mapping array receives the signal, it can more effectively evaluate the positioning accuracy of the lightning mapping array for cloud flashes;

[0049] (2) The present invention has high performance and high precision. It can generate an electromagnetic field similar to a real lightning signal, simulate various parameters when lightning occurs, support the generation of user-defined signals, and can transmit back the location and time of signal generation. It is suitable for research and testing in the fields of meteorology, lightning protection, aviation, and electricity. In addition, the signal parameters can be configured and the signal output time can be controlled through the serial port debugging assistant. The device adopts a modular design and can be expanded according to user needs, thereby reducing the difficulty of use.

[0050] It should be understood that the contents described in the summary of the invention are not intended to limit the key or important features of the embodiments of the present disclosure, nor are they intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] The above and other features, advantages and aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. The accompanying drawings are used to better understand the present solution and do not constitute a limitation of the present disclosure. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements, among which:

[0052] Figure 1 A schematic diagram of the structure of a lightning signal simulation system based on the VHF frequency band according to an embodiment of the present disclosure is shown;

[0053] Figure 2 A schematic diagram of an antenna communication method of a lightning signal simulation system based on a VHF frequency band according to an embodiment of the present disclosure is shown;

[0054] Figure 3 A schematic structural diagram of a lightning identification module of a ground receiver of a lightning signal simulation system based on a VHF frequency band according to an embodiment of the present disclosure is shown;

[0055] Figure 4 A schematic diagram of the structure of a control panel of a lightning signal simulation system based on the VHF frequency band according to an embodiment of the present disclosure is shown;

[0056] Figure 5 A schematic diagram of a Beidou module chip circuit of a lightning signal simulation system based on the VHF frequency band according to an embodiment of the present disclosure is shown;

[0057] Figure 6 A schematic diagram showing the connection between an MCU module and a signal generation module of a lightning signal simulation system based on a VHF frequency band according to an embodiment of the present disclosure is shown;

[0058] Figure 7 A timing diagram of a signal generation module chip of a lightning signal simulation system based on a VHF frequency band according to an embodiment of the present disclosure is shown;

[0059] Figure 8 A linear relationship diagram of input power-output voltage amplitude of a detection module of a lightning signal simulation system based on a VHF frequency band according to an embodiment of the present disclosure is shown;

[0060] Fig. 9 A schematic diagram of a detection module chip circuit of a lightning signal simulation system based on the VHF frequency band according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0061] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0062] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0063] Please refer to Figure 1 As shown, this embodiment provides a lightning signal simulation system based on the VHF frequency band, including a host computer, a lightning signal simulation device and a ground receiver;

[0064] The host computer communicates wirelessly with the lightning signal simulation device to send configuration commands to the lightning signal simulation device;

[0065] The lightning signal simulation device analyzes and processes the configuration commands, generates lightning simulation signals, and transmits them back to the ground receiver for reception;

[0066] The lightning signal simulation device includes a power supply, a data transmitter, a control panel, a power amplifier and an antenna;

[0067] The data transmitter is connected to the host computer, receives the configuration command of the host computer through the data transmitter and transmits it to the control board for processing to obtain the lightning simulation signal;

[0068] The power amplifier amplifies the analog signal and radiates it to the ground receiver through the antenna.

[0069] The lightning signal simulation device of this embodiment is installed on a drone, which controls take-off and movement to generate lightning simulation signals at different locations.

[0070] In this embodiment, the power amplifier uses a phase-locked loop frequency source, and the frequency range satisfies the bandwidth output of 35MHz to 300MHz. According to the actual working conditions, the power of the power amplifier is calculated by the following formula:

[0071] Los=P-Sen+Gr+Gt (1)

[0072] Among them, Los is the propagation loss, P is the power amplifier transmission power, Sen is the receiving sensitivity, Gr is the receiving antenna gain, and Gt is the transmitting antenna gain.

[0073] The above calculation results are based on an ideal propagation environment in an unobstructed vacuum environment. In actual communication environments, the propagation of radio waves is subject to various atmospheric attenuation, background noise interference, etc. Therefore, the sensitivity of the receiver in practice is much lower than this ideal value.

[0074] According to actual tests, in the application environment of the receiving system of the current lightning mapping array test, the atmospheric attenuation value in the actual environment ranges from 10dB to 14dB; therefore, in actual conditions, only when the transmitter power satisfies P>35dBm can the coverage distance of 100km be met. The minimum output power of the transmitter is 3W. Considering that this is a test and each lightning mapping array substation is a new design, the power amplifier output power is selected to be as high as 12W.

[0075] The antenna uses a four-arm array antenna, and the four arms are set under the drone of the antenna. The radiation array is perpendicular to the drone and the ground. The antenna array can be adjusted from 20cm to 80cm according to the required frequency band. Two antennas are used to switch the communication of the far area 50km to 60km away from the antenna and 1km directly below the antenna, respectively, to provide coverage. The correspondence between the antenna array length and frequency, and the switching of the two antennas in the near and far areas are adjusted by the MCU or APP software.

[0076] The design bandwidth of the antenna is 50MHz to 300MHz, and the operating bandwidth is any 6MHz within the design bandwidth. Figure 2 The communication mode of the antenna is calculated according to the UAV's take-off height and communication distance. For the stability of the system, the signal of the receiving antenna port is set to ≥-80dBm.

[0077] The antenna field strength includes near-field strength and far-field strength. Specifically,

[0078] The calculation method of near-zone field strength is:

[0079] Lf 1 =32.44+20lgl+20lgf 0 (2)

[0080] Lf 2 =32.44+20lgl+20lgf 0 -3 (3)

[0081]

[0082] Among them, Lfs 1 is the loss value when there is no near-field antenna, Lfs 2 is the loss value when there is a near-field antenna, f0 is the initial frequency, PT is the power, Pp1 is the near-field strength when there is no near-field antenna, and Pp2 is the near-field strength when there is a near-field antenna;

[0083] The far-zone field strength is calculated as:

[0084]

[0085] Where d is the distance between the transmitter and the receiver, f is megahertz, dBi is the antenna increment,

[0086] Gr(dBi)=101g (power density of the transmitting antenna toward the receiving end / power of an isotropic transmitting antenna with the same power in the same direction).

[0087] like Figure 3 As shown, the ground receiver receives the lightning simulation signal emitted by the antenna. Specifically, the ground receiver includes a lightning recognition module, which includes a preprocessor, a clock circuit, a time signal generator, and a lightning recognition unit; the preprocessor is used to process the received lightning simulation signal; the preprocessor and the lightning recognition unit are connected in sequence to realize the input and recognition of the lightning simulation signal; the clock circuit is connected to the time signal generator, the processor and the lightning recognition unit to provide and transmit the clock signal; the lightning recognition unit is used to identify the lightning signal processed by the preprocessor, and determine whether it is a lightning simulation signal of the lightning signal simulation device.

[0088] At the same time, the lightning identification module also includes a storage unit, which is connected to the lightning identification unit. The judgment result obtained by the lightning identification unit is stored in the storage unit for future use.

[0089] Further, specific, such as Figure 4 The control board shown includes an MCU module, an FPGA module, a signal generation module, a Beidou module, a RF switch module, a detection module, and a communication module;

[0090] The MCU module receives the transmission data from the Beidou module, communication module and detection module respectively, parses the command data of the communication module and controls the signal generation module to generate lightning simulation signals.

[0091] In this embodiment, the MCU module uses the STM32F103RCT6 chip, which is responsible for controlling each module and receiving data sent back by each module. The specific parameters of the chip are shown in Table 1.

[0092] Table 1 STM32F103RCT6 specific parameters

[0093]

[0094]

[0095] The Beidou module is connected to the MCU module and the FPGA module to provide time and position information to the MCU module and provide a 1PPS pulse signal to the FPGA module. In this embodiment, the Beidou module selects TAU3101, and TAU3101 provides a high-precision 1PPS time-scale signal with an accuracy better than 10ns (95%, PDOP≤4). The pulse signal of this embodiment uses 1PPS, the positive pulse width of the 1PPS signal is greater than 2ms, the rising edge of the 1PPS signal is the time synchronization point, and the rise time of the rising edge is less than 5ns. The user can adjust the 1PPS phase through the delay setting command. When the timing is valid, the distance between the first character of the TOD information and the rising edge of 1PPS is greater than 2ms. TAU3101 in this embodiment provides a full-duplex UART serial port with a baud rate of 9600, 1 start bit, 8 data bits, 1 stop bit, a data length of 54 bytes, and a packet header of @@Hb. See the simplified schematic circuit of Beidou using a passive antenna. Figure 5 , Beidou module is powered by DC 3.3V.

[0096] The performance indicators and electrical parameters of the Beidou module are shown in Table 2 and Table 3:

[0097] Table 2 Beidou module performance indicators

[0098]

[0099]

[0100] Table 3 Beidou module electrical parameters

[0101] name Specific parameters Operating voltage 3.3V Ripple voltage 50mV Working current range@3.3V 60mA to 100mA Antenna supply voltage 5V Antenna short circuit detection current threshold 260mA

[0102] The signal generation module is connected to the RF switch module, and is used to receive data from the MCU module, process the data to obtain an output signal of a specific frequency and power, and transmit the output signal to the RF switch module.

[0103] In this embodiment, the signal generation module selects MAX2870ETJ+. MAX2870 is an ultra-wideband phase-locked loop (PLL) with an integrated voltage-controlled oscillator (VCO), which can operate in integer and fractional-N frequency division modes. With an external reference clock oscillator and a loop filter, MAX2870 can form a high-performance frequency synthesizer, generate a clock with a frequency range of 23.5MHz to 6.0GHz, and maintain excellent phase noise and spurious indicators.

[0104] The MAX2870 serial port includes 5 write-only / 1 read-only 32-bit registers. The 3-31 most significant bits (MSB) of the register are data, and the 0-2 least significant bits (LSB) are the register address. The frequency and power of the output signal can be configured by loading register data through the 4-wire serial port (SPI). When LE is a logic low level, the logic signal at the DATA end is shifted in at the rising edge of CLK, and the 29 data bits are latched into the register selected by the address bit at the rising edge of LE. After power-on, the user must set all registers. The register setting order is: 0x05, 0x04, 0x03, 0x02, 0x01 and 0x00. According to Figure 6 Connect the MCU module and the MAX2870 signal generation module according to the block diagram. Figure 7 The timing diagram is used for software SPI communication. By configuring registers 0-5 of the MAX2870, a signal with a specified frequency and power can be output.

[0105] MAX2870 has 6 registers, register 6 is a read-only register, which contains the status information of MAX2870, and the other registers are write-only registers. The frequency and power of the MAX2870 output signal are configured by equations 1 to 3, specifically:

[0106]

[0107] In the formula, f REF Indicates the external reference clock input frequency. The reference clock input frequency of the VHF lightning signal simulator is 25MHz. DBR (register 2, bit 25) is used to set f REF Enter the frequency multiplication mode (0 or 1); RDIV2 (register 2, bit 24) is used to set f REF 2 mode (0 or 1); R (Register 2, Bits 23 to 14) is the 10-bit programmable reference clock counter value (1 to 1023). For fractional-N mode, the maximum f PFD is 50MHz; for integer-N mode, the maximum f PFD It is 105MHz.

[0108]

[0109] Where N is the value of the 16-bit counter (16 to 65535), which can be set by bits 30:15 of register 0; M is the fractional modulus (2 to 4095), which can be set by bits 14:3 of register 1; F is the divisor of the fraction (0 to MOD-1), which can be set by bits 14:3 of register 0. In fractional N mode, the minimum N value is 19 and the maximum N value is 4091. RST = 1 (register 2, bit 3), the N counter can be kept reset. DIVA is the RF output divider setting (0 to 7), which can be set by bits 22:20 of register 4. Its value range is shown in Table 4. FB is the feedback mode of the integrated voltage regulator (VCO), f vco is the fundamental frequency voltage, f RFOUA The frequency at which the chip generates the signal.

[0110] Table 4 DIVA value reference diagram

[0111]

[0112] It should be noted that the state machine clock f BS Must be set to 50kHz and is set by the BS bit. BS is set by the following formula.

[0113]

[0114] In the formula, f REF For the reference clock frequency, BS (register 4, bits 19 to 12) should be rounded to the nearest integer. If the calculated BS is higher than 1023, set BS = 1023. If f REF If the frequency is lower than 50KHz, set BS = 1. The time required to select the correct VCO is

[0115] The specific parameters of the signal generation module of this embodiment are shown in Table 5.

[0116] Table 5 Specific parameters of signal generation module

[0117]

[0118]

[0119] The RF switch module is connected to the power amplifier, outputs the signal of the specified window time, and amplifies the signal. The RF switch uses the HMC849ALP4CE chip, Vctl is the control pin, EN is the output enable pin, and when the EN pin is logic high, both output channel 1 and output channel 2 are closed. When the EN pin is logic low and the Vct1 pin is high, the signal is output from channel 1; when the EN pin is logic low and the Vct1 pin is low, the signal is output from channel 2.

[0120] The RF switch chip has two functions. One is to determine the window time width of the analog source by accurately controlling the RF switch time through FPGA, and the other is to connect with the detection module to measure the current power of the analog source. The switching time is adjustable from 30ns to 300ns to ensure that each window time contains 4 to 8 complete waveforms at different frequencies. The configuration work is completed by the MCU main control module. The RF switch chip selects HMC849, with a maximum input power of 30dBm and an isolation of 60dB. The truth table of the RF switch module is shown in Table 6. Configure the Vct1 and EN pins through FPGA to choose to open channel 1 or channel 2.

[0121] Table 6 RF switch truth table

[0122]

[0123]

[0124] The specific parameters of the RF switch module are shown in Table 7.

[0125] Table 7 Specific parameters of RF switch

[0126]

[0127] The detection module is connected to the MCU module, detects the radio frequency power of the radio frequency switch module, obtains a measurable voltage value, and transmits it to the MCU module.

[0128] The detection module of this embodiment uses a logarithmic detector, and the logarithmic detector chip uses AD8310ARMZ. The logarithmic detector has an extremely fast response time of 15ns, detects and compresses the intermediate frequency signal in dB equivalent form, and the maximum input power is +15dBm. The AD8310 input signal power and output voltage amplitude are linearly related. Figure 8 The following is a linear relationship diagram of input power-output voltage amplitude corresponding to frequencies of 200MHz, 300MHz, and 440MHz at an ambient temperature of 25°C. The output voltage amplitude is measured, and the input signal power can be obtained based on the linear relationship between input power and output voltage amplitude.

[0129] AD8310 is an ultra-fast response, versatile logarithmic detection chip. Based on progressive compression technology, it can demodulate and amplify DC-400MHz signals. When the frequency does not exceed 100MHz, it can provide a dynamic range of 95dB (±3dB law consistency) and 90dB (±1dB tight error limit). The specific parameters are shown in Table 8.

[0130] Table 8 Logarithmic detector specific parameters

[0131] name Specific parameters Supply voltage 5V Input Power -100dBm to 15dBm Differential drive Maximum 22dBm Input frequency range 0 to 440MHz Internal power dissipation Max. 220mW Output voltage range 0.34V to 2.7V Input Impedance 50Ω Output Current 2mA Operating temperature -40℃ to +85℃ Industrial Grade

[0132] Fig. 9 This is the application circuit of AD8310. The output of RF switch channel 1 is used as the signal input of AD8310, and the output of AD8310 is used as the input of MCU ADC. After a lot of tests, the linear relationship between the output amplitude of AD8310 and the input signal power at different frequencies is obtained, and the linear relationship is fitted into a straight line. The power of the input signal is calculated according to the following formula, specifically:

[0133] V OUT =V sLOPE ×(P IN -P 0 ) (11)

[0134] Among them, V OUT is the output voltage amplitude, Vx LOPE is the logarithmic slope, P IN is the input signal power, P O is the log intercept.

[0135] The communication module is connected to the MCU module, and wireless transmission between the user end and the MCU module is realized through the communication module.

[0136] In this embodiment, the communication module selects the E22-400TXXX series LoRa wireless module, which is based on the wireless serial port module (UART) of the SX1268 radio frequency chip, has multiple transmission modes, works in the (410.125MHz to 493.125MHz) frequency band (default 433.125MHz), and has a communication distance of 10km. Connect the data transmitter to the PC, the communication module to the MCU, and wireless communication between the data transmitter and the communication module to achieve wireless data transmission between the PC and the MCU.

[0137] The communication module has four 8-bit registers. You can configure the serial port rate, serial port baud rate, air rate, etc. by writing to the registers. Before writing to the registers, you need to select the mode 0 configuration mode (M0 pin is low, M1 pin is high) for the working mode of the communication module. Table 9 is the instruction list supported by the communication module, and Table 10 is the register description. You can complete the communication module configuration by writing instructions according to the instruction list and register description. After the configuration is completed, you need to switch the working mode to the general mode (M0 pin is low, M1 pin is low) for the module to communicate normally.

[0138] Table 9 Command formats supported by the communication module

[0139]

[0140]

[0141]

[0142] Table 10 Communication module register description

[0143]

[0144]

[0145]

[0146] Use the serial port debugging assistant to configure the module address (0x1234), network address (0x00), serial port (96008N1), and airspeed (2.4K) at the same time.

[0147] Start two serial port debugging assistants, select the serial port baud rate as 9600bps, the verification mode as 8N1, and set the address and channel of the communication module and the data transmitter to be the same, then serial port transparent transmission can be achieved.

[0148] The specific parameters of the communication module are shown in Table 11.

[0149] Table 11 Communication module specific parameters

[0150]

[0151]

[0152] The FPGA module is connected to the Beidou module, the MCU module and the RF switch module to analyze the data of the Beidou module and the MCU module and send switch instructions to the RF switch module.

[0153] The FPGA module uses Lattice's MACHXO2 family series LCMXO2-1200HC chip. The MACHXO2 series chip has 6 devices with a density range of 256 to 6864 lookup tables (LUTs). In addition to low-cost programmable logic based on LUT, the chip also has embedded block RAM (EBR), distributed RAM, user flash memory (UFM), and phase-locked loop (PLL). The MachXO2 series is designed with a 65nm non-volatile low-power process and has the characteristics of flexible logic architecture, ultra-low power consumption, instant startup, high security, and low cost. The specific parameters of the FPGA are shown in Table 12.

[0154] Table 12 FPGA specific parameters

[0155] name Specific parameters Supply voltage 2.375V to 3.465V Total RAM bits 65536 Number of LABs / CLBs 160 Operating temperature 0℃ to +85℃ frequency 269MHz Number of logic elements / units 1280 IO Number 79 Program storage type FLASH Embedded memory size 64Kbit Maximum propagation delay time 8.03ns

[0156] It should be noted that, for the aforementioned method embodiments, for the sake of simplicity, they are all described as a series of action combinations, but those skilled in the art should be aware that the present disclosure is not limited by the order of the actions described, because according to the present disclosure, certain steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all optional embodiments, and the actions and modules involved are not necessarily required by the present disclosure.

[0157] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps recorded in this disclosure can be executed in parallel, sequentially or in different orders, as long as the desired results of the technical solutions disclosed in this disclosure can be achieved, and this document does not limit this.

[0158] The above specific implementations do not constitute a limitation on the protection scope of the present disclosure. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A lightning signal simulation system based on VHF frequency band, characterized in that: It includes a host computer, a lightning signal simulation device and a ground receiver; The host computer communicates wirelessly with the lightning signal simulation device and is used to send a configuration command to the lightning signal simulation device; The lightning signal simulation device analyzes and processes the configuration command, generates a lightning simulation signal and radiates it to the ground receiver; The lightning signal simulation device includes a power supply, a data transmitter, a control board, a power amplifier, and an antenna; the data transmitter is connected to the host computer, receives the configuration command of the host computer through the data transmitter and transmits it to the control board for processing to obtain the lightning simulation signal and the status information and output information of the lightning signal simulation device; the power amplifier amplifies the lightning simulation signal and radiates it to the ground receiver through the antenna, and the status information and output information are transmitted back to the host computer, and the power supply provides power for the control board and the power amplifier.

2. The lightning signal simulation system according to claim 1, characterized in that: The state information and output information include time data, position data, signal configuration data and AD data.

3. The lightning signal simulation system according to claim 1, characterized in that: The amplification power of the power amplifier is calculated as follows: Los=P-Sen+Gr+Gt (1) Among them, Los is the propagation loss, P is the power amplifier transmission power, Sen is the receiving sensitivity, Gr is the receiving antenna gain, and Gt is the transmitting antenna gain.

4. The lightning signal simulation system according to claim 1, characterized in that: The antenna field strength includes near-field strength and far-field strength, specifically: The calculation method of near-field strength is: Lfs1=32.44+20lg l+20lg f0 (2) Lfs2=32.44+20lg l+20lg f0-3 (3) Where Lfs1 is the loss value without near-field antenna, Lfs2 is the loss value with near-field antenna, f0 is the initial frequency, P T is power, P p1 is the near field strength when there is no near field antenna, P p2 is the near-field strength when there is a near-field antenna; The far-zone field strength is calculated as: Where d is the distance between the transmitter and the receiver, f is megahertz, dBi is the antenna increment, Gr(dBi)=101g (power density of the transmitting antenna toward the receiving end / power of an isotropic transmitting antenna with the same power in the same direction).

5. The lightning signal simulation system according to claim 1, characterized in that: The control board includes a Beidou module, an MCU module, a signal generation module, a radio frequency switch module, a detection module, an FPGA module and a communication module; The communication module is connected to the MCU module to realize data interaction between the host computer and the MCU module; The Beidou module is connected to the MCU module and is used to collect time and location information and transmit it to the MCU module; The signal generating module is connected to the MCU module and is used to generate a lightning simulation signal; The RF switch module is connected to the signal generation module to control whether the analog signal is output. The RF switch module is also connected to the power amplifier to output a signal of a specified window time and amplify the signal. The MCU module receives the transmission data from the Beidou module, the communication module and the detection module respectively, and controls the signal generation module to generate a lightning simulation signal by parsing the command data from the communication module.

6. The lightning signal simulation system according to claim 5, characterized in that: The Beidou module adopts the TAU3101 Beidou GPS timing receiving module, which can receive the Beidou satellite B1 frequency civil code signal and the GPS satellite L1 frequency C / A code signal; The RF switch module adopts HMC849ALP4CE chip; The MCU module adopts the STM32F103RCT6 chip, which can realize the module control function and receive the data sent back by the module; The signal generation module uses the MAX2870ETJ+ chip.

7. The lightning signal simulation system according to claim 5, characterized in that: The process of generating a signal by the signal generating module is as follows: Among them, f REF Indicates the external reference clock input frequency. The reference clock input frequency of the VHF lightning signal simulator is 25MHz. DBR is set to bit 25 of register 2. REF Input frequency multiplication mode 0 or 1; RDIV2 is register 2 bit 24 setting f REF The 2-division mode is 0 or 1; R is the programmable reference clock counter value at bit 10 of register 2, which is 1 to 1023; Where N is the value of the 16-bit counter, which is 16 to 65535; M is the fraction modulus, which is 2 to 4095; F is the divisor of the fraction, which is 0 to MOD-1; DIVA is the RF output divider, which is set to 0 to 7; FB is the feedback mode of the integrated pressure controller, f vco is the fundamental frequency voltage, f RFOUA The frequency at which the signal is generated for the chip.

8. The lightning signal simulation system according to claim 5, characterized in that: The FPGA module is connected to the Beidou module, the MCU module and the RF switch module respectively, and is used to analyze the data of the Beidou module and the MCU module and send a switch instruction to the RF switch module; The detection module is connected to the RF switch module and the MCU module respectively, and is used to detect the RF power of the lightning simulation signal of the RF switch module, convert it into a measurable voltage value, and transmit it to the MCU module.

9. The lightning signal simulation system according to claim 1, characterized in that: The ground receiver includes a lightning identification module, which includes a preprocessor, a clock circuit, a time-scale signal generator, a lightning identification unit and a storage unit; The preprocessor is connected to the lightning identification unit to implement input and identification of the lightning simulation signal; The time-stamp signal generator is connected to the preprocessor and is used to identify and determine the signal reception time; The clock circuit is connected to the time-stamp signal generator, the preprocessor and the lightning identification unit, and is used to provide and transmit a clock signal; The lightning identification unit is used to identify the lightning signal processed by the preprocessor and determine whether it is a lightning simulation signal of the lightning signal simulation device; The storage unit is connected to the lightning identification unit, and the judgment result obtained by the lightning identification unit is stored in the storage unit for standby use.

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