CN201555946U - Full Lightning Locating System Combining VLF and VHF - Google Patents

Abstract

The utility model is a full lightning location system combining very low frequency and very high frequency, which is characterized in that the system includes at least four lightning location monitoring stations, and the lightning location monitoring stations are equipped with very low frequency lightning radiation receivers, VHF lightning radiation receiver, GPS receiver, industrial computer, the site uses the GPS receiver to provide a time reference, obtains the time and waveform of the lightning electric field change pulse and the VHF radiation pulse arriving at each site, and utilizes the industrial computer to analyze the obtained waveform The data is preprocessed, and then the obtained data is transmitted to the industrial computer for analyzing and processing the pulse waveform in real time through the Internet, so as to realize real-time monitoring and three-dimensional positioning of lightning discharge events. With the cooperation of the above-mentioned hardware and software, the system can be used to determine the quantity, type and characteristic parameters of lightning discharge events in a designated area, as well as their statistical characteristics, and monitor and warn lightning activities.

Description

Full Lightning Locating System Combining VLF and VHF

technical field

The utility model relates to meteorological observation equipment, in particular to a very low frequency and very high frequency full lightning positioning system.

Background technique

Lightning is one of the most serious natural disasters, which can cause fires in forests and oil depots, cause failure or damage to power supply and communication information systems, and pose a major threat to aerospace, mines, and some important and sensitive high-tech equipment. After the 1980s, the damage caused by lightning has increased significantly, especially in fields closely related to high-tech, such as aerospace, national defense, communications, electric power, computers, and electronics industries. VLSI has greatly increased the probability of being struck by lightning; according to conservative estimates, the direct economic loss caused by lightning damage in my country exceeds hundreds of millions of yuan each year, and the indirect economic loss and impact caused by it are difficult to estimate. It has brought great difficulties to its research, forecast and prevention.

The lightning detection and location system can provide early warning of lightning activity, thereby reducing the harmful effects of lightning. Since lightning location systems can continuously monitor the temporal and spatial evolution of "ground flashes" and "cloud flashes", and even the development of discharge channels, these systems can also be used to determine the number of lightning occurrences in a specified area, as well as the statistical characteristics of discharge parameters, Therefore, developing new lightning detection technology is a very urgent task at present.

Utility model content

The purpose of this utility model is to overcome the defects in the prior art and design a full lightning positioning system combining very low frequency and very high frequency. According to the characteristics of lightning radiation and the specific requirements of lightning detection, the system is specially designed to collect and analyze lightning radiation signals system of record. The system can be used to determine the number of lightning occurrences in a specified area, as well as the statistical characteristics of discharge parameters, and can provide early warning of lightning activities.

In order to achieve the above purpose, the full lightning location system of the present utility model adopts a technical solution combining very low frequency and very high frequency. The system includes at least five lightning location monitoring stations, and what lightning location monitoring stations are installed Low-frequency lightning radiation receiver, VHF lightning radiation receiver, GPS receiver, industrial computer, and PCI data acquisition card; the PCI data acquisition card is provided with a pulse peak acquisition channel, a data segment acquisition channel, a second synchronization module, Sampling clock module and PCI controller; the very low frequency lightning radiation receiver is connected to the data segment acquisition channel, and the signal detected by the very low frequency lightning radiation receiver is collected through the data segment acquisition channel; the very high The frequency lightning radiation receiver is connected with the pulse peak acquisition channel, and the signal detected by the VHF lightning radiation receiver is collected through the pulse peak acquisition channel; the GPS receiver is connected with the second synchronization module; The GPS receiver is connected with the sampling clock module through the GPS clock module; the GPS receiver is connected to the serial port of the industrial computer, and the GPS serial port information is input; the PCI data acquisition card is inserted into the PCI slot provided on the industrial computer. Slots, passing data through the PCI bus.

Wherein, the very low frequency lightning radiation receiver includes a receiving antenna, an integrating amplifier, a filter, a drive output circuit, an analog/digital conversion circuit and a recording device connected in sequence, and the receiver is used to detect and receive the transient electric field generated by lightning Variety.

Wherein, the VHF lightning radiation receiver includes a receiving antenna, a preselection filter, a frequency converter, an intermediate frequency filter, a logarithmic amplifier, a drive output circuit, an analog/digital conversion circuit and a recording device connected in sequence, and the receiver It is used to detect VHF radiation signals generated by small-scale discharge processes.

Wherein, the industrial computer is provided with the data acquisition module and data processing software, and the data processing software is used to analyze and process the lightning waveform, and obtain the time stamp of the arrival of the lightning radiation signal.

Wherein, the GPS receiver, the very low frequency lightning radiation receiver, and the very high frequency lightning radiation receiver are integrated in the industrial computer, and the GPS receiver is used for frequency reference correction and outputs accurate frequency signals , while also providing an accurate time reference to the system.

Wherein, the antenna in the VHF lightning radiation receiver is a disc-cone antenna, and the disc-cone antenna is a linearly polarized broadband omnidirectional antenna.

Wherein, the data acquisition unit is provided with two independent sampling channels, and the highest data sampling rates of the two channels are 5 MS/s and 50 MS/s respectively.

Wherein, the industrial computer is provided with a trigger circuit and a memory, and the trigger circuit is used to trigger the acquisition of the lightning waveform, lightning radiation intensity and signal time when the signal received by the acquisition component is greater than the set threshold. stamp, and transmit data over the Internet, while storing said signal into said memory.

The advantages and beneficial effects of the utility model are: with the cooperation of the above-mentioned hardware and software, the system can be used to determine the quantity of lightning (cloud flash and ground flash) in a designated area, the temporal and spatial evolution characteristics of lightning, the discharge type, and the discharge type. The statistical characteristics of the parameters and the early warning of lightning activities.

Description of drawings

Fig. 1 is the block diagram of the full lightning positioning system of the utility model combining very low frequency and very high frequency;

Fig. 2 is a block diagram of the very low frequency lightning radiation receiver system in the full lightning positioning system combined with very low frequency and very high frequency of the present invention;

Fig. 3 is a block diagram of the VHF lightning radiation receiver system in the all-lightning locating system combining VLF and VHF of the present invention;

Fig. 4 is the structural block diagram of the GPS clock module in the all-lightning positioning system combining very low frequency and very high frequency of the present invention;

Fig. 5 is a flow chart of tuning voltage control algorithm software in the full lightning positioning system combined with very low frequency and very high frequency of the present invention; Err in Fig. 5: frequency error absolute value; Nzflag: current error polarity; Preig: last error polarity Zlag: number of continuous zero errors; Incre: increment of control amount;

Fig. 6 is a structural block diagram of the data acquisition card in the all-lightning positioning system combining very low frequency and very high frequency of the present invention.

Detailed ways

Below in conjunction with accompanying drawing and embodiment, the specific embodiment of the utility model is further described. The following examples are only used to illustrate the technical solution of the utility model more clearly, but not to limit the protection scope of the utility model.

As shown in accompanying drawing 1 to Fig. 5, the technical scheme of the concrete implementation of the utility model is:

As shown in accompanying drawing 1, a kind of very low frequency and very high frequency combined lightning location system, this system comprises at least five lightning location monitoring stations, is provided with very low frequency lightning radiation receiver, very high frequency lightning radiation receiver in described lightning location monitoring station Frequency lightning radiation receiver, GPS receiver, industrial computer, said site utilizes GPS receiver to provide absolute time reference, obtains the time and waveform of lightning VLF/LF radiation pulse and VHF radiation pulse arriving at each site, utilizes industrial computer to obtain The waveform data is preprocessed, and then the obtained data is transmitted to the industrial computer for analyzing and processing the pulse in real time through the Internet, so as to realize real-time monitoring and three-dimensional positioning of lightning discharge events.

Generally speaking, the signal detected by the very low frequency system often corresponds to the larger-scale current process in the lightning discharge process, and usually only one effective position can be obtained, while the radiation signal generated by the smaller-scale breakdown process detected by the VHF system, It can detect the initial breakdown, pilot discharge and other processes of the cloud flash discharge process, and can also describe the lightning channel. Therefore, this utility model combines the characteristics of these two lightning location systems, and adopts the joint scheme of the detection system of the very low frequency and the very high frequency band, and has developed and completed this set that can detect both ground lightning and cloud lightning (including some that occur in cloud full lightning detection equipment for special discharge events within the

The occurrence of lightning has a large discreteness, and a huge number of radiation pulses will be generated during the lightning-intensive time period. To completely monitor lightning events, the system must accurately record the characteristic parameters and occurrence time of each lightning discharge event, that is, it must design a A system structure with a high data throughput rate is used to achieve reliable recording of all events during lightning-intensive periods, and the result of this is not only a huge amount of lightning detailed waveform data, but also makes the time and cost of post-analysis very high. For most Not worth it for monitoring purposes. Therefore, according to the characteristics of lightning radiation and the specific requirements of lightning detection, the utility model specially designs and develops a lightning radiation signal collection, analysis and recording system.

This set of lightning detection system is a combination of very low frequency and very high frequency radiation. It is mainly composed of very low frequency lightning radiation receiver, very high frequency lightning radiation receiver, GPS clock synchronization system and lightning radiation signal data acquisition system. The very low frequency lightning radiation receiver is used to detect the transient electric field changes generated by lightning. Its principle is similar to that of the commonly used fast electric field change instrument. The working frequency range is 200Hz~3MHz; the VHF lightning radiation receiver is mainly used to detect small-scale discharges For the radiation signal generated in the process, in order to avoid the interference of local wireless communication signals, the center frequency of the receiver is continuously adjustable at 30-300MHz, and the bandwidth is 8MHz. The lightning radiation signal is processed by preselection filtering, frequency conversion, intermediate frequency filtering, and logarithmic amplification. Make it a signal suitable for data sampling and send it to the data acquisition system. Precise clock information is obtained from the GPS receiver, and the local oscillator is synchronized by the GPS's 1PPS reference signal. The digital integrated circuit (CPLD) with logical function on the system board can process the characteristics of the analog/digital (A/D) acquisition data in two time windows in real time, and record the precise time stamp. The data collector digitizes the electric field change and VHF radiation signal at a sampling rate of 5Msps and 50Msps respectively, after which the signal is continuously compared with the preset numerical trigger threshold, when the signal strength exceeds the given threshold, the digitized electric field change waveform is collected by means of The card (industrial computer I) bus transmits to the memory of the industrial computer, captures every electric field change pulse without any dead time, and extracts the waveform characteristic parameters in real time, and then the original waveform and waveform parameters are written into the storage medium. For the VHF signal, use the Field Programmable Gate Array FPGA (Field Programmable Gate Array ) on the data acquisition card to windowize the digitized radiation field signal, record the signal peak value, time, and other important Waveform parameters and transfer format data are output to a buffer (FIFO), and the industrial computer extracts the data from the FIFO and writes it to the storage medium.

As shown in Figure 1, the whole system hardware is composed of very low frequency lightning radiation receiver, very high frequency lightning radiation receiver, GPS receiver, data acquisition card and industrial computer.

As shown in Figure 2, the very low frequency lightning radiation receiver described in the utility model includes a receiving antenna, an integrating amplifier, a filter, a drive output circuit, an analog/digital conversion circuit and a recording device connected in sequence, and the receiver uses It is used to detect and receive transient electric field changes generated by lightning.

As shown in Figure 3, the VHF lightning radiation receiver includes a receiving antenna, a preselection filter, a frequency converter, an intermediate frequency filter, a logarithmic amplifier, a drive output circuit, an analog/digital conversion circuit and a recording device connected in sequence, The receiver is used to detect the radiation signal generated by the small-scale discharge process. The radiation signal of lightning in the VHF frequency band is mainly produced by a small-scale breakdown process, which can detect the initial breakdown of lightning, the pilot discharge and other processes, and can describe the development channel of lightning in more detail. The research on the temporal and spatial evolution characteristics of occurrence and development, and the research on the relationship between lightning characteristics and thunderstorm precipitation characteristics have high practical value. However, in this frequency band, there are also various wireless communication signals, and these signals are different in different regions or at different time periods. These signals sometimes seriously affect the normal operation of the VHF lightning detection system. Based on the above situation, the utility model has specially developed a tuning type lightning VHF signal receiver. By controlling the computer RS232 interface, its center frequency can be adjusted arbitrarily within 30MHz ~ 300MHz. This function makes the installation and erection of the lightning location detection system easier, more flexible and convenient, without having to know the electromagnetic environment near the installation site in advance. The receiver consists of a local oscillator (FS0330) and a receiver (RE0330). It has a logarithmic detection output and an intermediate frequency output. The bandwidth of the video output is 8MHz, and the bandwidth of the intermediate frequency output is 20MHz.

In order to cooperate with the tuned UHF receiver, a dish cone antenna is used, which is a linearly polarized broadband omnidirectional antenna.

GPS Clock Module Design

The GPS receiver selects Motorola's M12T high-precision GPS timing module. The module can track 12 satellites at the same time, and output high-precision 1PPS pulse signal and NEMA-0183 serial port data. The 1PPS signal can be used for the calibration of the sampling clock and the second synchronization of the acquisition card. The serial port data includes information such as UTC time, longitude, latitude, altitude and receiver status, providing accurate time and acquisition environment information for the acquisition system.

The GPS clock module uses the 1PPS pulse sent by the GPS receiver as a reference to generate a high-precision and high-stability 100M clock signal to provide a high-quality sampling clock source for the PCI data acquisition card to reduce time errors and improve lightning positioning accuracy.

GPS receiver module composition and principle

The GPS clock module adopts an analog-digital hybrid and software phase-locked scheme structure, and its structure is shown in Figure 4. The output of the 10M voltage-controlled temperature-compensated crystal oscillator (VCTCXO) is multiplied to obtain a 100M clock. This clock is used as the clock of the counter with a modulus of 10,000 inside the FPGA. The FPGA latches the value of the counter at the rising edge of each 1PPS pulse and sends it to the M6759 microcontroller. Apply for interruption, after the industrial computer reads the count value and compares it with the last count value to obtain the error of the second output clock, the error is converted into the digital tuning voltage of the voltage-controlled temperature-compensated crystal oscillator in the industrial computer according to the tuning voltage control algorithm , After digital-to-analog (D/A) conversion, the VCTCXO is controlled to form a closed-loop control.

The advantage of this scheme is that the long-term stability of the output frequency is guaranteed by the 1PPS signal of GPS, while the short-term stability depends on the VCTCXO crystal oscillator. The temperature stability of the selected voltage-controlled temperature-compensated crystal oscillator is ±0.5ppm, and the annual aging rate is 1ppm.

Since the stability of the voltage-controlled temperature-compensated crystal oscillator is ±0.5ppm, the frequency change of the crystal oscillator under the control voltage of 0-5V is -200-300Hz after testing, so a counter with a modulus of 10,000 is selected to leave sufficient margin. On the one hand, the 50MHz clock is sent to the counter with a modulus of 10,000 as the counting pulse. On the other hand, it is used as the clock to sample the rising edge of the 1PPS pulse. The collected rising edge signal is used as the latch of the counter and the interrupt application signal of the microcontroller. When the external read The interrupt request signal can be automatically cleared when the count value is fetched.

The temperature stability of the actual selected voltage-controlled temperature-compensated crystal oscillator is ±0.5ppm, the aging is 1ppm, the adjustment range of the control voltage is 0-5V, and the D/A adopts TLC5618 with a conversion accuracy of 12 bits. The tuning voltage control algorithm calculates the tuning voltage according to the frequency error and the number of consecutive zero error seconds. The error model of the voltage-controlled temperature-compensated crystal oscillator at the equilibrium position can be approximated as a proportional link with disturbance, and its control law is When the frequency error is greater than 1, take twice the error as the increment of the tuning voltage. When the error is less than or equal to 1, the increment of the tuning voltage is obtained according to the continuous zero error number and the error polarity lookup table. The software flow of this part is shown in Figure 5. shown.

GPS clock module peripheral hardware expansion

In order to expand the GPS clock module more conveniently, the communication channels between the GPS clock module and the outside include the RS232 serial port and the PC104 bus. The serial NEMA-0183 data can be read through the RS232, and the analyzed NEMA-0183 data can be directly read through the PC104 bus. Data, in which the analysis of NEMA-0183 data is realized in the single chip microcomputer.

data acquisition card

The PCI data acquisition card used in this system is transformed from a parallel two-channel data acquisition card. The PCI data acquisition card uses 1PPS pulse as the second synchronization signal and the output of the GPS clock module as the sampling clock. The two channels independently complete the pulse peak characteristic acquisition and lightning waveform acquisition of lightning radiation, and send the acquired data to the industrial computer through the PCI bus.

Data acquisition card hardware structure

The core algorithm of the PCI data acquisition card adopts FPGA design, which has high integration and reliability. The maximum sampling frequency of the A/D converter used in this machine is 70Msps, and the resolution is 12 bits. Suppose, the structure of the data acquisition card is shown in Figure 6.

Second synchronization and pulse peak acquisition

The principle of second synchronization and pulse peak acquisition is shown in Figure 7. The acquisition card resets the sampling clock cycle counter within a second of the acquisition card on the rising edge of each 1PPS pulse, so that the count value of the counter can represent the precise moment of a certain pulse peak value within the second, so that the data of each distributed node has a unified The time reference point realizes the timing synchronization between nodes and can effectively eliminate the time accumulation error of long-term monitoring of the system. The identification of the pulse peak value adopts the time window maximum value method. Firstly, according to the actual characteristics, select the appropriate time window width and trigger level for the pulse peak value acquisition. Record the second number, amplitude, pulse width and sampling cycle count value corresponding to the maximum value, and combine the four into a pulse record. If the maximum amplitude is greater than the set trigger level, press the pulse record into the Capture the cache of the card, otherwise discard the record.

The sampling time window search method may cause one input pulse to generate two pulse peak records. When the input pulse spans several windows, several pulses may be output. The identification of discharge pulses increases information, and reduces errors or misjudgments of signal properties in multi-site data fusion and lightning location calculations.

Pulse peak acquisition greatly reduces data volume. For the pulse peak acquisition system with 50MHz sampling frequency and 12-bit A/D conversion, the second data throughput is slightly 100M during continuous waveform acquisition, and there are great difficulties in data transmission, storage and analysis. When using pulse peak acquisition, if the selected time window width is 10us, a maximum of 100,000 pulse peak records will be generated, each pulse peak record occupies 6 bytes, and its total occupied space is 1/166 of that of continuous waveform acquisition. It greatly reduces the difficulty of data storage, transmission and processing.

Data Segment Collection

The data segment acquisition channel is used to collect fast electric field change signals. The sampling frequency of this channel is low, generally at 2MHz, but it is required to continuously collect the input at this frequency. In order to reduce the data volume of this channel, the segment acquisition method is adopted. This channel has a trigger level and acquisition depth set according to the actual situation. Every time it is triggered, the acquisition card will continuously acquire a data segment of the set depth. Each segment is composed of segment start flag, segment start second number, segment start second time, valid data and segment end mark. The start flag and end flag of the segment are determined according to the attributes of the signal. The A/D of the acquisition card is 12 bits. When the acquisition card transmits data to the upper layer, two consecutive acquisition values are spliced into a 24-bit number and transmitted through the PCI bus. For the industrial computer, the A/D value of the acquisition card corresponding to 0 data is 0x0, and the A/D value corresponding to the full scale is 0xfff, under normal circumstances, there will not be fusion from minimum to maximum or maximum to minimum twice in a row, so The data of this channel takes 0x000fff and 0x000fff as the start mark of a segment, and takes 0xfff000 and 0xfff000 as the end mark of the segment.

Data transfer between data acquisition card and industrial computer

The PCI bus is used to transfer data between the acquisition card and the industrial computer. Since the GPS data is transmitted to the industrial computer through the serial port, and the collected data is transmitted to the industrial computer through the PCI bus, in order to ensure that the serial port data of a certain second and the PCI bus data of the second can be correctly corresponded in time, the PCI data acquisition card The data transmission must ensure strict real-time performance, so the data acquisition card will apply for an interruption to the industrial computer at the rising edge of each 1PPS pulse, and will also apply for an interruption to the industrial computer when the amount of data reaches a certain amount, and the industrial computer responds to the interruption. The data on the PCI data acquisition card is all read to the industrial computer.

The above is only the preferred embodiment of the utility model, and it should be pointed out that for those of ordinary skill in the art, without departing from the technical principle of the utility model, some improvements and modifications can also be made. And retouching should also be regarded as the protection scope of the present utility model.

Claims (8)

1. A full lightning locating system combining very low frequency and very high frequency, it is characterized in that, the system includes at least four lightning location monitoring sites, and the lightning location monitoring site is provided with very low frequency lightning radiation receivers, even High-frequency lightning radiation receiver, GPS receiver, industrial computer, and PCI data acquisition card; said PCI data acquisition card is provided with pulse peak acquisition channel, data segment acquisition channel, second synchronization module, sampling clock module and PCI controller The very low frequency lightning radiation receiver is connected to the data segment acquisition channel, and the signal detected by the very low frequency lightning radiation receiver is collected through the data segment acquisition channel; The pulse peak acquisition channel is connected, and the signal detected by the VHF lightning radiation receiver is collected through the pulse peak acquisition channel; the GPS receiver is connected with the second synchronization module; the GPS receiver passes the GPS clock The module is connected with the sampling clock module; the GPS receiver is connected to the serial port of the industrial computer, and the GPS serial port information is input; the PCI data acquisition card is inserted into the PCI slot provided on the industrial computer, and the data is transmitted through the PCI bus . 2. the full lightning locating system that very low frequency and very high frequency combine as claimed in claim 1, is characterized in that, described very low frequency lightning radiation receiver comprises receiving antenna, integral amplifier, filter, drive output that are connected successively circuit, the receiver transmits the received signal to the analog/digital conversion circuit and data recording equipment in the industrial computer, and the receiver is used to detect and receive transient electric field changes generated by lightning. 3. the full lightning locating system that very low frequency and very high frequency combine as claimed in claim 1, is characterized in that, described very high frequency lightning radiation receiver comprises receiving antenna, preselection filter, frequency converter, intermediate frequency connected in sequence Filter, logarithmic amplifier, drive output circuit, the receiver transmits the received signal to the analog/digital conversion circuit and recording equipment in the industrial computer, and the receiver is used to detect the VHF generated by the small-scale discharge process of lightning Radiation signal. 4. as claimed in claim 2 or 3 described very low frequency and the full lightning location system that very high frequency combines, it is characterized in that, described industrial computer is provided with lightning pulse waveform data acquisition circuit and data processing software, and described data processing The software is used to analyze, process and extract the lightning waveform, the characteristic parameters of the lightning waveform and the arrival time of the lightning signal. 5. the full lightning locating system that very low frequency and very high frequency combine as claimed in claim 4, is characterized in that, described GPS receiver, described very low frequency lightning radiation receiver, described very high frequency lightning radiation receiver Integrated in the industrial computer, the GPS receiver is used for frequency reference correction, outputs accurate frequency signals, and also provides an accurate time reference for the system. 6. the full lightning locating system that very low frequency and very high frequency combine as claimed in claim 5 is characterized in that, the antenna in the described very high frequency lightning radiation receiver is a dish cone antenna, and the described dish cone antenna is a linear Polarized broadband omnidirectional antenna. 7. the full lightning locating system that very low frequency and very high frequency combine as claimed in claim 6, is characterized in that, described data acquisition part is provided with 2 independent sampling channels, the highest data sampling rate of described two channels They are 5MS/s and 50MS/s respectively. 8. The full lightning location system combined with very low frequency and very high frequency as claimed in claim 2 or 3, characterized in that, the industrial computer is provided with a trigger circuit and a memory, and the trigger circuit is used when the acquisition card receives After the detected monitoring signal is greater than the set threshold, the trigger circuit is triggered and records the lightning pulse waveform, extracts the characteristic parameters of the lightning waveform and the time stamp of the corresponding lightning event, stores the data in the memory, and simultaneously passes The internet is sent to the computer used for lightning location processing.

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