A field measurement device for electromagnetic signals of ocean ground wave radar

Abstract

The present invention discloses a field measurement device for electromagnetic signals of ocean ground wave radar. The device comprises: a standard signal transmitting unit, a standard gain antenna, a shell, and a comprehensive data processing system installed inside the shell, a broadband receiving unit, an antenna bias unit, and a rechargeable built-in battery; the standard signal transmitting unit comprises a positioning module, a dedicated DDS chip for generating a standard fixed frequency signal, and a transmitting antenna connected to the signal output end of the DDS chip; the ground wave radar antenna receives the signal emitted by the transmitting antenna of the standard signal transmitting unit; the standard gain antenna is used to receive the wireless electromagnetic signal emitted by the ground wave radar; the broadband receiving unit comprises a radio frequency and signal processing circuit for extracting the spectral characteristics of the input signal; the comprehensive data processing system is connected to the output end of the radio frequency and signal processing circuit. The present invention has the characteristics of high integration and can support long-term continuous measurement and real-time signal processing.

Description

Technical Field

[0001] The invention relates to the technical field of ocean monitoring, and in particular to an on-site measurement device for electromagnetic signals of ocean ground wave radar. Background Art

[0002] As an emerging ocean monitoring technology, high-frequency ground wave radar has the advantages of beyond-horizon, large range, all-weather and low cost. It is considered to be a high-tech means to effectively monitor the exclusive economic zones of various countries. Ground wave radar is a new ocean observation technology that uses the characteristics of high-frequency electromagnetic waves with low attenuation of diffraction propagation on the coastal water surface to measure sea surface flow fields, wave fields, wind fields and other elements based on the radar backscattered Bragg signal. Ground wave radar can provide refined sea surface flow fields for offshore disaster prevention and mitigation, offshore oil spills, maritime search and rescue, route protection, etc., and is one of the most advantageous observation methods for offshore marine environment protection at this stage.

[0003] As a means of on-site electromagnetic signal "telemetry", the on-site electromagnetic environment will affect the electromagnetic signal, causing changes in field strength and distortion of antenna patterns, which will directly affect the flow measurement range and observation accuracy of ground wave radar. At the same time, the drift of key radio parameters such as observation frequency, power, and bandwidth will affect the spatial resolution of its flow field observation and interfere with surrounding radio equipment, causing adverse social impacts. Therefore, in order to ensure the accuracy of high-frequency ground wave radar flow measurement and support ground wave radar radio management, it is necessary to regularly conduct metrological inspection and calibration of key radio parameters of ground wave radar equipment.

[0004] At present, the field measurement of electromagnetic signals of ground wave radar generally adopts discrete general instruments, and the system integration is not high; the electromagnetic environment of ground wave radar varies greatly at different times and seasons, and long-term continuous observation is required. Since ground wave radar is usually installed on the seashore, the existing instruments cannot meet the needs of long-term field observation of ground wave radar; the antenna pattern of ground wave radar is one of the important factors affecting the measurement of sea state elements, which is greatly affected by its surrounding environment (such as buildings, metal facilities, etc.), and the existing discrete equipment cannot complete the measurement of this parameter or the measurement is difficult. The electromagnetic environment of the ground wave radar is very complex. There are not only signals of the radar's own working frequency, but also electromagnetic signals of many other frequency bands, which brings certain difficulties to the measurement of electromagnetic signal field strength parameters. At present, the field strength is measured by a field strength meter, but the field strength meter measures the electromagnetic signals of all frequency bands within the measured frequency range and then gives the composite field strength, rather than the field strength of a specific frequency band or frequency point. This method cannot meet the field strength measurement of important indicators such as useful signals, interference signals, and environmental noise within the radar working frequency band, and cannot meet the use requirements in the radar working environment. The measurement data processing and analysis of existing equipment are not real-time, and it is impossible to use time-frequency analysis methods for signal processing. It lacks functions such as automatic data recording and processing. Summary of the invention

[0005] The purpose of the present invention is to provide an on-site measurement device for electromagnetic signals of ocean ground wave radar, which has the characteristics of high integration and can support long-term continuous measurement and real-time processing of signals.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] An on-site measurement device for electromagnetic signals of ocean ground wave radar comprises: a standard signal transmitting unit, a standard gain antenna, a shell, a comprehensive data processing system installed inside the shell, a broadband receiving unit, an antenna bias unit and a rechargeable built-in battery;

[0008] The standard signal transmitting unit includes a positioning module, a dedicated DDS chip for generating a standard fixed frequency signal, and a transmitting antenna connected to the signal output end of the DDS chip; the ground wave radar antenna receives the signal emitted by the transmitting antenna of the standard signal transmitting unit;

[0009] The standard gain antenna is used to receive the wireless electromagnetic signal transmitted by the ground wave radar, and the shape structure and polarization mode of the standard gain antenna are consistent with the shape structure and polarization mode of the ground wave radar transmitting antenna;

[0010] The broadband receiving unit includes a radio frequency and signal processing circuit, and the radio frequency and signal processing circuit is used to extract the frequency spectrum characteristics of the input signal;

[0011] The integrated data processing system is connected to the output end of the radio frequency and signal processing circuit;

[0012] When measuring the frequency, bandwidth, frequency band to be measured and the field strength at the frequency point of the signal, the input end of the radio frequency and signal processing circuit is connected to the output end of the standard gain antenna through the antenna bias unit, and the integrated data processing system determines the frequency, bandwidth, frequency band to be measured and the field strength at the frequency point of the input signal according to the frequency spectrum characteristic signal output by the radio frequency and signal processing circuit; when measuring the antenna pattern of the ground wave radar, the input end of the radio frequency and signal processing circuit is connected to the output end of the ground wave radar receiving antenna through the antenna bias unit, and the integrated data processing system determines the antenna pattern of the ground wave radar according to the frequency spectrum characteristic signal output by the radio frequency and signal processing circuit and the position information provided by the positioning module;

[0013] The rechargeable internal battery is used to power the broadband receiving unit, the integrated data processing system and the antenna bias unit.

[0014] Optionally, the measuring device also includes: a bidirectional coupler and an attenuator. When measuring the transmission power of the ground wave radar transmitter, the bidirectional coupler is installed between the ground wave radar transmitter and the ground wave radar transmitting antenna, the input end of the attenuator is connected to the coupling output end of the bidirectional coupler, and the output end of the attenuator is connected to the input end of the radio frequency and signal processing circuit.

[0015] Optionally, the isolation of the bidirectional coupler is not less than 30 dB.

[0016] Optionally, the RF and signal processing circuit includes: a RF signal processing subunit, a FPGA-based digital signal processing subunit and a microprocessor, wherein the microprocessor is used to control the processing process of the FPGA; the input signal of the RF and signal processing circuit is output after passing through the RF signal processing subunit and the digital signal processing subunit in sequence.

[0017] Optionally, the RF signal processing subunit includes: a local oscillator, a RF input attenuator, a low-pass filter, an amplifier, a mixer, a bandpass filter and an analog-to-digital converter. The input signal passes through the RF input attenuator, the low-pass filter and the amplifier in sequence and enters the mixer. The local oscillator signal emitted by the local oscillator enters the mixer through the amplifier. The mixed output signal passes through the bandpass filter to obtain a difference frequency signal, and the difference frequency signal is output after passing through the analog-to-digital converter.

[0018] Optionally, the FPGA-based digital signal processing subunit includes: a digital down-conversion module, a low-pass filtering module, a speed reduction extraction module and a spectrum calculation module. The digital down-conversion module is composed of a multiplier and a direct digital synthesizer. The signal output by the analog-to-digital converter is output after passing through the digital down-conversion module, the low-pass filtering module, the speed reduction extraction module and the spectrum calculation module in sequence.

[0019] Optionally, the standard signal transmitting unit also includes: a processor, a power module, a data transmission radio and an antenna; the processor receives external input parameters through the UART interface, forms control parameters of the DDS chip through analysis and processing, and writes the control parameters into the DDS chip through the SPI port; the processor is also used to extract the location information received by the positioning module, and transmit the location information to the integrated data processing system through the data transmission radio and antenna; the power module supplies power to the standard signal transmitting unit.

[0020] Optionally, the comprehensive data processing system includes a data transmission module, a data processing and analysis module, and a display and control module. The data transmission module is used to complete data transmission, the data processing and analysis module is used to complete analysis and storage of spectrum characteristic signals, and the display and control module is used to display measurement data, display a human-computer interaction interface, and provide input of equipment parameters, equipment measurement parameters, and instructions.

[0021] Optionally, a handle and running wheels are provided on the shell.

[0022] Optionally, a power supply interface for an integrated data processing system, a charging interface for a rechargeable built-in battery, and a data transmission interface for a broadband receiving unit are provided on the top surface of the shell.

[0023] According to the specific embodiment provided by the present invention, the present invention discloses the following technical effects: the marine ground wave radar electromagnetic signal on-site metering device provided by the present invention integrates a standard signal transmitting unit, a standard gain antenna, an integrated data processing system, and a broadband receiving unit. The standard signal transmitting unit can transmit a continuous signal of a set frequency and the latitude and longitude information of the location. By using it in conjunction with the broadband receiving unit and the integrated data processing system, the on-site metering of the ground wave radar antenna pattern can be completed. The standard gain antenna is used to receive the wireless electromagnetic signal, and the radio frequency and signal processing circuit extracts the spectrum characteristics of the ground wave radar electromagnetic signal. In conjunction with the analysis and processing of the integrated data processing system, the frequency and bandwidth characteristics of the radar wireless electromagnetic signal can be obtained in real time. The standard gain antenna, the antenna bias unit, the radio frequency and signal processing circuit, and the integrated data processing system can be used in conjunction to complete the field strength measurement at the frequency band and frequency point to be measured. The radio frequency and signal processing circuit, the bidirectional coupler, the attenuator, and the integrated data processing system can be used in conjunction to complete the measurement of the ground wave radar transmission power. It can be seen that the present invention realizes the real-time measurement of the key electrical parameters of the marine ground wave radar electromagnetic signal. Moreover, the metering device provided by the present invention is provided with a large-capacity rechargeable built-in battery, which can support long-term continuous measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0025] Figure 1 This is a schematic diagram of the basic structure of an on-site measurement device for electromagnetic signals of an ocean ground wave radar according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram of radar transmission power measurement in an embodiment of the present invention;

[0027] Figure 3 This is a front view of the internal structure of the housing in an embodiment of the present invention;

[0028] Figure 4 It is a side view of the internal structure of the housing in an embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram of the structure of the radio frequency and signal processing circuit in an embodiment of the present invention;

[0030] Figure 6 It is a software structure diagram of the comprehensive data processing system in an embodiment of the present invention.

[0031] 1. Bottom-layer fixed aluminum plate; 2. Cooling fan fixing bracket; 3. Middle-layer fixed aluminum plate; 4. Upper-layer fixed aluminum plate; 5. Antenna bias unit; 6. Integrated data processing system installation slot; 7. Standard gain antenna; 8. Antenna RF connector; 9. Shell; 10. Large-capacity rechargeable built-in battery; 11. Cooling fan; 12. Integrated data processing system power supply interface; 13. Built-in battery charging interface; 14. Built-in battery charging status display; 15. Push button switch; 16. Beidou / GPS positioning antenna. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] 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.

[0034] The present invention provides an on-site measuring device for electromagnetic signals of ocean ground wave radar, which comprises: a standard signal transmitting unit, a standard gain antenna, a shell, and a comprehensive data processing system installed inside the shell, a broadband receiving unit, an antenna bias unit, and a rechargeable built-in battery;

[0035] The standard signal transmitting unit includes a positioning module, a dedicated DDS chip for generating a standard fixed frequency signal, and a transmitting antenna connected to the signal output end of the DDS chip, and the electromagnetic signal emitted by the transmitting antenna is received by the ground wave radar antenna;

[0036] The standard gain antenna is used to receive the wireless electromagnetic signal transmitted by the ground wave radar, and the shape structure and polarization mode of the standard gain antenna are consistent with the shape structure and polarization mode of the ground wave radar transmitting antenna; wherein, the standard gain antenna can adopt a whip antenna consistent with the shape structure and polarization mode of the ground wave radar transmitting antenna, the antenna has a wider frequency band range, a lower standing wave ratio, and its important indicators such as antenna directional diagram and gain are calibrated to ensure the accuracy of the device in measuring the wireless electromagnetic signal;

[0037] The broadband receiving unit includes a radio frequency and signal processing circuit, and the radio frequency and signal processing circuit is used to extract the frequency spectrum characteristics of the input signal;

[0038] like Figure 1 As shown, the integrated data processing system is connected to the output end of the broadband receiving unit.

[0039] When measuring the frequency, bandwidth, frequency band to be measured and field strength at the frequency point of the signal, the input end of the radio frequency and signal processing circuit is connected to the output end of the standard gain antenna through the antenna bias unit. At this time, the integrated data processing system determines the frequency, bandwidth, frequency band to be measured and field strength at the frequency point of the input signal according to the spectrum characteristic signal output by the radio frequency and signal processing circuit. In this embodiment, the radio frequency and signal processing circuit can obtain the power value of each frequency point in the frequency band to be measured by extracting the spectrum characteristics of the wireless electromagnetic signal. Since the standard gain antenna has a constant and known antenna factor in the operating frequency band of the ground wave radar, the field strength value at the frequency point to be measured can be calculated according to the definition formula of the antenna factor.

[0040] When measuring the antenna pattern of the ground wave radar, the input end of the radio frequency and signal processing circuit is connected to the output end of the ground wave radar antenna, and the integrated data processing system determines the antenna pattern of the ground wave radar based on the frequency spectrum characteristic signal output by the radio frequency and signal processing circuit and the position information provided by the standard signal transmitting unit positioning module.

[0041] The rechargeable internal battery is used to power the broadband receiving unit, the integrated data processing system and the antenna bias unit.

[0042] On the basis of the above embodiment, the measuring device in this embodiment further includes: a bidirectional coupler and an attenuator. When measuring the transmission power of the ground wave radar transmitter, Figure 2 As shown, the bidirectional coupler is installed between the ground wave radar transmitter and the ground wave radar transmitting antenna, the input end of the attenuator is connected to the coupling output end of the bidirectional coupler, and the output end of the attenuator is connected to the input end of the radio frequency and signal processing circuit.

[0043] As an optional implementation, the bidirectional coupler may be a bidirectional coupler with an isolation of not less than 30 dB.

[0044] The metering device provided by the present invention is mainly composed of a broadband receiving unit, a standard gain antenna, an integrated data processing system and a standard signal transmitting unit. The first three units constitute the main part of the metering device. The standard signal transmitting unit can complete the on-site measurement of the antenna pattern by cooperating with the main part of the metering device. The broadband receiving unit measures the electromagnetic signal of the ground wave radar based on the spectrum analysis method, and obtains the frequency and bandwidth characteristics of the radar radio electromagnetic signal in real time. By using a coupler and an attenuator, the broadband receiving unit can complete the on-site measurement of the radar transmitter transmission power; by using a standard gain antenna, the broadband receiving unit can complete the field strength measurement at the frequency band and frequency point to be measured; the standard signal transmitting unit can transmit a continuous signal of a set frequency and the longitude and latitude information at the location, and by combining with the main part of the metering device, the metering device can complete the measurement of the radar antenna pattern on site. The above measurement results are all processed, displayed, analyzed and saved in real time by the integrated data processing system. The main part of the metering device is equipped with a large-capacity rechargeable battery, which is suitable for long-term automatic observation in the field. By using the on-site measurement data of the metering device of the present invention to calibrate the ocean ground wave radar, the measurement accuracy of the radar can be improved, and effective and real-time management of the working status of the ocean ground wave radar can be achieved.

[0045] It should be emphasized that the specific method or specific software module used by the integrated data processing system in the above-mentioned embodiment to determine the frequency, bandwidth, field strength, directivity pattern and radar transmitter transmission power of the signal according to the spectrum characteristic signal output by the radio frequency and signal processing circuit is a conventional method or module in this field, and the present invention will not elaborate on it, which does not belong to the content required to be protected by the present invention.

[0046] In the above embodiment, if Figure 3 and Figure 4As shown, a three-layer structure can be designed in the shell 9, the bottom layer can be installed with a large-capacity rechargeable built-in battery 10, the middle layer can be installed with a radio frequency and signal processing circuit board, and a reserved installation position for the antenna bias unit 5 is convenient for loading and unloading the unit; the top layer can be provided with a comprehensive data processing system installation slot 6, such as an installation slot for a laptop computer with supporting data processing software installed. Two groups of cooling fans 11 can also be installed in the bottom layer. Five key switches 15 can be set, respectively for system startup, broadband receiving unit power supply, antenna bias unit power supply, comprehensive data processing system power supply and cooling fan switch, and the switch form adopts a self-locking switch with LED and other indicators. The top panel can be provided with a comprehensive data processing system power supply interface 12, a built-in battery charging interface 13, and a circuit board data transmission interface to facilitate data cross-linking and power supply between the system and external devices. The shell body is made of a durable and lightweight plastic material, and can be equipped with walking wheels and handles for easy transportation in outdoor environments.

[0047] The broadband receiving unit in the above embodiment uses the basic idea of ​​spectrum analysis and adopts a superheterodyne structure to extract the spectrum characteristics of the electromagnetic signal. The radio frequency and signal processing circuit may include: a radio frequency signal processing subunit, a digital signal processing subunit based on FPGA and a microprocessor, wherein the microprocessor is used to control the processing process of the FPGA; the input signal of the radio frequency and signal processing circuit is output after passing through the radio frequency signal processing subunit and the digital signal processing subunit in sequence. The high-frequency ground wave radar electromagnetic signal enters the broadband receiving unit through the ground wave radar antenna or the standard gain antenna, and the upper frequency limit in the signal path is limited to 100MHz by a low-pass filter. An amplifier is used to amplify the local oscillator signal and the low-pass filter output signal to make it meet the signal input range of the mixer. The result after the mixing output is filtered out by bandpass filtering and the sum frequency signal is retained. It is subjected to analog-to-digital conversion, and the digital signal processing after sampling is all completed by FPGA and ARM, and the processed result is transmitted to the integrated data processing system.

[0048] like Figure 5As shown, the RF signal processing subunit may include: a local oscillator, a RF input attenuator, a low-pass filter, an amplifier, a mixer, a band-pass filter and an analog-to-digital converter. The input signal passes through the RF input attenuator, the low-pass filter and the amplifier in sequence and enters the mixer. The local oscillator signal emitted by the local oscillator enters the mixer through the amplifier. The mixed output signal passes through the band-pass filter to obtain a difference frequency signal, which is output after passing through the analog-to-digital converter. The FPGA-based digital signal processing subunit may include: a digital down-conversion module, a low-pass filtering module, a speed reduction extraction module and a spectrum calculation module. The digital down-conversion module is composed of a multiplier and a direct digital synthesizer. The signal output by the analog-to-digital converter passes through the digital down-conversion module, the low-pass filtering module, the speed reduction extraction module and the spectrum calculation module in sequence and then is output.

[0049] The design and selection of each device in the radio frequency signal processing subunit can be specifically as follows:

[0050] In order to ensure that the input signal amplitude of the mixer meets the input requirements, the mixer front-end amplifier circuit can use the chip AD8009 produced by ADI. This chip is an ultra-high-speed current feedback amplifier, which is suitable for amplifying the local oscillator signal to meet the mixing voltage of the multiplier. At the same time, it can also bias the baseband signal to facilitate the sampling requirements of the subsequent ADC. Impedance matching is performed on the input stage when designing the circuit.

[0051] The local oscillator can use the DDS dedicated chip AD9958 produced by ADI. This chip is a high-performance, excellent dynamic characteristic, dual-channel DDS device produced by Analog Devices. Each channel can control the frequency, phase, and amplitude separately. The chip can generate dual-channel signals with a maximum frequency of 250MHz. There are many control registers inside it for controlling the output signal parameters. When the system completes the measurement in the 3-50MHz frequency band, it is necessary to control the local oscillator signal generated by AD9958. The frequency, phase, and amplitude of the local oscillator signal are related to the corresponding control word of AD9958. According to the basic principle of superheterodyne, the linear scanning mode is adopted in the design. The ARM chip is used as the main control chip of the system. Through programming of this chip, the data content of the serial buffer can be sent to the internal register of AD9958, and the local oscillator signal can be output to realize the frequency sweep.

[0052] The AD835 chip is used as the mixer. This chip is an analog multiplier with a 250MHz four-quadrant voltage output. The product noise is only 50nV / Hz, and it can complete the function of outputting W=X*Y+Z signals. Since filters with lower operating frequencies are easier to implement, the difference frequency signal of the mixing output is extracted. Impedance matching is performed at the input and output stages during design to avoid voltage reflection. The local oscillator signal and the input signal are connected to the X1 and Y1 channels of the mixer respectively. The input impedance and output impedance are both 50Ω, the input voltage range is -1 to +1V, and the bandwidth is 40MHz.

[0053] AD sampling uses the AD9244 chip, which is an analog-to-digital converter with a 14-bit sampling bit number and a sampling point number of 40Msps per second at a power consumption of 300mW. In this design, AD9244 uses a sampling rate of 40MHz to sample the analog input signal, and the technical indicators of this chip meet the design requirements.

[0054] The design of each module in the FPGA-based digital signal processing subunit is selected as follows:

[0055] The digital down-conversion module consists of a multiplier and a direct digital synthesizer. The carrier frequency of the intermediate frequency signal after the RF front-end processing is 10MHz. After 40MHz sampling, the signal is down-converted. The direct digital synthesizer (DDS) in the IP core is called inside the FPGA to generate a 9.8MHz sinusoidal signal as the local oscillator signal. After mixing, the two signals are mixed to obtain signals with carrier frequencies of 200kHz and 19.8MHz.

[0056] The low-pass filter module uses a low-pass filter to filter out the signal with a center frequency of 19.8MHz after down-conversion and retain the 200kHz signal according to the requirements of the subsequent algorithm. The filter adopts the form of FIR. When designing, the passband cutoff frequency and stopband start frequency are determined in combination with the measured data while ensuring that the filter order is small.

[0057] The speed reduction module needs to perform a series of digital signal processing on the signal output by the low-pass filter, and too high a sampling rate will affect the performance of subsequent signal processing and occupy too many resources, so the filtered signal needs to be slowed down. Here, a sampling rate of 400kHz is used to resample the signal.

[0058] Assume that the original sampling sequence is x(n), and extract one data every D-1 data (double extraction) to form a new sequence x1(m), that is:

[0059] x1(m)=x(Dm)(m, D are both integers)

[0060] The signal after low-pass filtering is extracted and filtered to reduce the data rate from 40MSps to a suitable level. Because the bandwidth of the ground wave radar electromagnetic signal is less than 150kHz, in order to improve real-time performance and reduce the amount of calculation for subsequent signal processing, based on the Nyquist sampling theorem, a sampling rate of 400kHz is used for speed reduction extraction, that is, D=400 in the above formula, reducing the data rate to 400kSps.

[0061] The spectrum calculation module uses the IP core in the FPGA to complete the fast Fourier transform (FFT) of the digital signal. The selected FPGA can complete the FFT transformation of 65536 points at a time. Since the signal sampling rate has been reduced to 400kHz after descaling, it can meet the processing requirements of FFT. The signal after FFT transformation is processed by envelope detection and transmitted to the integrated data processing system through the LAN transmission line. Its frequency is used as the horizontal component, and the vertical axis shows the signal amplitude, and the spectrum of the input signal is drawn on the screen of the system.

[0062] The broadband receiving unit uses radio frequency circuits, digital circuits and microprocessor architecture, and has storage and computing functions. It is equipped with a standard interface and, as an important component of the metering device, completes the measurement of wireless electromagnetic signals.

[0063] In practical applications, the standard signal transmitting unit may also include: a processor, a power module, a data transmission radio and an antenna. The standard signal transmitting unit can transmit a fixed frequency continuous signal and current location information, has an operating frequency of 3-50MHz, has a GNSS positioning function, and has an embedded system. Among them, the positioning module can receive GPS and Beidou signals, and the horizontal positioning accuracy is better than 10 meters. The longitude and latitude information is extracted and processed by the ARM processor and then transmitted through the antenna of the data transmission radio. The processor receives external input parameters through the UART interface, forms the control parameters of the DDS chip through analysis and processing, and writes the control parameters into the DDS chip through the SPI port. The DDS chip generates a standard fixed frequency signal according to the control parameters, and its output is filtered out of the band by a bandpass filter. The out-of-band spurious signal is then transmitted through the transmitting antenna after power amplification. The transmitting antenna adopts a high-gain omnidirectional antenna in the ground wave radar frequency band to ensure reliable signal transmission. The power module supplies power to the standard signal transmitting unit.

[0064] like Figure 6As shown, the comprehensive data processing system may include a data transmission module, a data processing and analysis module, and a display and control module. The data transmission module is responsible for controlling the data communication between each measurement unit of the software and the computer, and the communication between the measurement system and other devices; including the packaging and unpacking of the measurement data and the control instruction protocol, the data input of the radar and the signal transmitting unit, etc. In order to ensure the high reliability of the data transmission module and ensure that the measurement data is not lost, an independent process mode is adopted and the background operation is carried out. The data processing and analysis module completes the calculation of the measurement elements such as the field strength value according to the equipment parameters and the measurement data, automatically analyzes the signal characteristics, and stores the measurement results. According to the measurement data, positioning data and radar data, the calculation of the antenna pattern is completed. The display and control module provides a human-computer interaction interface for the measurement system, provides the input of equipment parameters, equipment measurement parameters and instructions; displays the measurement data such as frequency, power, bandwidth, field strength in real time; can display the spectrum, and can display the spectrum waterfall diagram.

[0065] The ground wave radar electromagnetic signal on-site metering device provided by the present invention has the following advantages:

[0066] 1. Built-in large-capacity rechargeable battery, which can support the device to measure continuously for 24 hours, meet the needs of long-term continuous observation, and is suitable for long-term unattended observation of ground wave radar and its surrounding electromagnetic environment at different times and seasons;

[0067] 2. The system has high integration and diversified measurement indicators. During measurement, the system can be remotely set according to the on-site environment, and the operation is simple;

[0068] 3. It can conduct on-site measurement of ground wave radar antenna pattern. The calibrated ground wave radar can improve the accuracy of sea state element measurement;

[0069] 4. It can measure the composite field strength of the ground wave radar working frequency band or the field strength of a specific frequency point, so as to ensure the measurement of environmental noise, radar signal and interference signal field strength.

[0070] 5. Able to complete real-time measurement and data analysis of ground wave radar electromagnetic signals on site.

[0071] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0072] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A marine ground wave radar electromagnetic signal on-site measurement device, characterized in that: include: A standard signal transmitting unit, a standard gain antenna, a housing, and a comprehensive data processing system installed inside the housing, a broadband receiving unit, an antenna bias unit, and a rechargeable internal battery; The standard signal transmitting unit includes a positioning module, a dedicated DDS chip for generating a standard fixed frequency signal, and a transmitting antenna connected to the signal output end of the DDS chip; the ground wave radar antenna receives the signal emitted by the transmitting antenna of the standard signal transmitting unit; The standard gain antenna is used to receive the wireless electromagnetic signal transmitted by the ground wave radar, and the shape structure and polarization mode of the standard gain antenna are consistent with the shape structure and polarization mode of the ground wave radar transmitting antenna; The broadband receiving unit includes a radio frequency and signal processing circuit, and the radio frequency and signal processing circuit is used to extract the frequency spectrum characteristics of the input signal; The integrated data processing system is connected to the output end of the radio frequency and signal processing circuit; When measuring the frequency, bandwidth, frequency band to be measured and the field strength at the frequency point of the signal, the input end of the radio frequency and signal processing circuit is connected to the output end of the standard gain antenna through the antenna bias unit, and the integrated data processing system determines the frequency, bandwidth, frequency band to be measured and the field strength at the frequency point of the input signal according to the frequency spectrum characteristic signal output by the radio frequency and signal processing circuit; when measuring the antenna pattern of the ground wave radar, the input end of the radio frequency and signal processing circuit is connected to the output end of the ground wave radar receiving antenna through the antenna bias unit, and the integrated data processing system determines the antenna pattern of the ground wave radar according to the frequency spectrum characteristic signal output by the radio frequency and signal processing circuit and the position information provided by the positioning module; The rechargeable internal battery is used to power the broadband receiving unit, the integrated data processing system and the antenna bias unit.

2. The on-site measurement device for electromagnetic signals of ocean ground wave radar according to claim 1 is characterized in that: The measuring device also includes: a bidirectional coupler and an attenuator. When measuring the transmission power of the ground wave radar transmitter, the bidirectional coupler is installed between the ground wave radar transmitter and the ground wave radar transmitting antenna, the input end of the attenuator is connected to the coupling output end of the bidirectional coupler, and the output end of the attenuator is connected to the input end of the radio frequency and signal processing circuit.

3. The on-site measurement device for electromagnetic signals of ocean ground wave radar according to claim 2 is characterized in that: The isolation of the bidirectional coupler is not less than 30dB.

4. The on-site measurement device for electromagnetic signals of ocean ground wave radar according to any one of claims 1 to 3, characterized in that: The RF and signal processing circuit includes: a RF signal processing subunit, a digital signal processing subunit based on FPGA and a microprocessor, wherein the microprocessor is used to control the processing process of the FPGA; the input signal of the RF and signal processing circuit is output after passing through the RF signal processing subunit and the digital signal processing subunit in sequence.

5. The on-site measurement device for electromagnetic signals of ocean ground wave radar according to claim 4 is characterized in that: The RF signal processing subunit includes: a local oscillator, a RF input attenuator, a low-pass filter, an amplifier, a mixer, a band-pass filter and an analog-to-digital converter. The input signal passes through the RF input attenuator, the low-pass filter and the amplifier in sequence and enters the mixer. The local oscillator signal emitted by the local oscillator enters the mixer through the amplifier. The mixed output signal passes through the band-pass filter to obtain a difference frequency signal, and the difference frequency signal is output after passing through the analog-to-digital converter.

6. The on-site measurement device for electromagnetic signals of ocean ground wave radar according to claim 5, characterized in that: The FPGA-based digital signal processing subunit includes: a digital down-conversion module, a low-pass filtering module, a speed reduction extraction module and a spectrum calculation module. The digital down-conversion module is composed of a multiplier and a direct digital synthesizer. The signal output by the analog-to-digital converter passes through the digital down-conversion module, the low-pass filtering module, the speed reduction extraction module and the spectrum calculation module in sequence before being output.

7. The on-site measurement device for electromagnetic signals of ocean ground wave radar according to claim 1 is characterized in that: The standard signal transmitting unit also includes: a processor, a power module, a data transmission radio and an antenna; the processor receives external input parameters through the UART interface, forms control parameters of the DDS chip through analysis and processing, and writes the control parameters into the DDS chip through the SPI port; the processor is also used to extract the location information received by the positioning module, and transmit the location information to the integrated data processing system through the data transmission radio and the antenna; the power module supplies power to the standard signal transmitting unit.

8. The on-site measurement device for electromagnetic signals of ocean ground wave radar according to claim 1 is characterized in that: The comprehensive data processing system includes a data transmission module, a data processing and analysis module, and a display and control module. The data transmission module is used to complete data transmission, the data processing and analysis module is used to complete the analysis and storage of spectrum characteristic signals, and the display and control module is used to display measurement data, display a human-computer interaction interface, and provide input of equipment parameters, equipment measurement parameters, and instructions.

9. The on-site measurement device for electromagnetic signals of ocean ground wave radar according to claim 1, characterized in that: The shell is provided with a handle and running wheels.

10. The on-site measurement device for electromagnetic signals of ocean ground wave radar according to claim 1, characterized in that: The top surface of the shell is provided with a power supply interface of the integrated data processing system, a charging interface of a rechargeable built-in battery, a data transmission interface of a broadband receiving unit, a built-in battery power display screen and a key switch.

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