CN111983617B - Dual-polarization phased array weather radar - Google Patents
Dual-polarization phased array weather radar Download PDFInfo
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S13/00—Systems using the reflection or reradiation of radio waves, e.g. radar systems; Analogous systems using reflection or reradiation of waves whose nature or wavelength is irrelevant or unspecified
- G01S13/88—Radar or analogous systems specially adapted for specific applications
- G01S13/95—Radar or analogous systems specially adapted for specific applications for meteorological use
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
- Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
- Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation
Abstract
The invention relates to a dual-polarization phased array weather radar, which is characterized in that a waveguide split plane antenna array is formed by alternately configuring a horizontal polarization antenna and a vertical polarization antenna; the DTRU subsystem consists of a DTRU module and a heat dissipation fan; a digital beam forming/signal processing subsystem consisting of a signal processing module, an optical transmission module and a timing synchronization module; the system comprises a servo subsystem, a frequency source and distribution network subsystem and a monitoring subsystem, and can meet the requirements of multiple working modes of double-transmitting and double-receiving, single-transmitting and double-receiving and single-transmitting and single-receiving of the whole system. The working requirements of pitching dimensional phase scanning and single/multi-beam receiving can be realized, the weather target information is rapidly detected, and the occurrence and development of disastrous weather such as rainstorm, hailstone, tornado and the like are effectively monitored; meanwhile, the dual polarization has good performance of quantitatively measuring the intensity of the echo, and large-range precipitation can be quantitatively estimated; the fixed point, quantification and timing of precipitation forecast are realized, and reliable and scientific detection data are provided for civil and military meteorological guarantee.
Description
Technical Field
The invention relates to the field of radars, in particular to a dual-polarization phased array weather radar.
Background
The weather radar is one of weather radars, is a main tool for monitoring and early warning strong convection weather, and has the working principle that the spatial position, the strong and weak distribution, the vertical structure and the like of rainfall are obtained by transmitting a series of pulse electromagnetic waves and utilizing the scattering effect of precipitation particles such as cloud, fog, rain, snow and the like on the electromagnetic waves. The radar can effectively monitor occurrence and development of disastrous weather such as rainstorm, hail, tornado and the like; meanwhile, the method has good performance of quantitatively measuring the intensity of the echo, and can quantitatively estimate large-scale precipitation; the fixed point, quantification and timing of precipitation forecast are realized, and reliable and scientific detection data are provided for civil and military meteorological guarantee.
The radar for the active service operation weather adopts a mechanical scanning antenna, only has a single wave beam, generally needs 6-8 minutes to complete the primary airspace detection, and for aviation dangerous weather such as thunderstorm, downburst, wind shear and the like, the fine three-dimensional structure of the dangerous weather cannot be obtained immediately due to small scale and high change speed, so that the identification, monitoring and early warning of the dangerous weather are influenced. In order to ensure the detection data quality, only the number of body scanning elevation angles can be reduced, and the full coverage of a pitching airspace cannot be achieved, so that the method influences the acquisition of refined three-dimensional structural data of aviation dangerous weather such as thunderstorms, strong winds, downburst flows, wind shear and the like, and effectively detects the rapidly-changing medium and small-scale weather dangers such as the thunderstorms, the downburst flows and the like.
Under the background of global climate change abnormity, disastrous and sudden weather is increased day by day, the weather guarantee pressure is increased day by day, novel weather radar equipment is urgently required to be developed, and the detection capability of short-term dangerous weather is further improved. By adopting the phased array weather radar technology, the detection period of the dangerous weather with strong convection, such as thunderstorms, strong winds and the like, can be shortened, the average early warning time of the dangerous weather, such as downburst flow, mesoscale cyclone and the like, is prolonged from less than 10 minutes to 15 minutes at present, and the accurate detection and forecast of the short-term dangerous weather are realized.
The phased array dual-polarization Doppler weather radar has the advantages that the polarization measurement function is added on the basis of the phased array weather radar, micro physical information such as cloud and rain target particle phase, particle size spectrum and dielectric constant is further acquired on the basis of weather target intensity, speed and spectrum width information acquired by the single-polarization phased array weather radar, the precision of quantitative measurement precipitation and water content in cloud of the phased array weather radar is greatly improved, cloud and rain target phase and zero-degree layer identification is realized, and the forecasting and ensuring capability of disastrous weather is greatly improved. The phased array dual-polarization weather radar is developed, more microscopic information of weather targets can be acquired, the short dangerous weather fine detection is improved, and the phased array dual-polarization weather radar has an important effect on realizing weather radar detection technology crossing and realizing the updating of weather radar equipment.
Disclosure of Invention
The invention aims to overcome the defects of the prior art, provides a dual-polarization phased array weather radar based on a waveguide slot array antenna, and can meet the requirements of multiple polarization working modes of dual-transmitting and dual-receiving, single-transmitting and dual-receiving and single-transmitting and single-receiving of a whole system. The radar can realize the pitching phase scanning and the single/multi-beam working requirement, quickly detect the weather target information of the airspace surrounding the radar and provide timely, reliable and comprehensive weather information for the military and civil weather guarantee system.
The purpose of the invention is realized by the following technical scheme:
a dual polarization phased array weather radar, comprising:
a waveguide split plane antenna array is formed by alternately configuring a horizontal polarization antenna and a vertical polarization antenna;
the DTRU subsystem consists of a DTRU module and a heat dissipation fan;
a digital beam forming/signal processing subsystem consisting of a signal processing module, an optical transmission module and a timing synchronization module;
a servo subsystem, a frequency source and distribution network subsystem and a monitoring subsystem;
when transmitting, the DDS in each DTRU module of the full array plane generates an excitation signal according to a designated amplitude and phase control word and combines a clock and a timing signal to generate a transmission, the excitation signal is input into the antenna units through up-conversion and power amplification, and each antenna unit generates a corresponding polarized electromagnetic wave to radiate to a designated airspace for power synthesis to form a transmission beam;
when receiving, the waveguide slot plane antenna array sends the reflected electromagnetic wave signals in a receiving airspace to the DTRU module, the signals are subjected to low-noise amplification and down-conversion to intermediate frequency, the intermediate frequency signals are subjected to A/D sampling and digital down-conversion processing to generate digital orthogonal video signals I/Q, the digital orthogonal video signals I/Q are sent to a digital beam forming system, and the digital beam forming system randomly forms required receiving beams in the scanning airspace through the weighting control of the amplitude and the phase of each channel signal.
Furthermore, the horizontally polarized antenna is formed by adopting a ridge waveguide narrow side to open an oblique slit, and the vertically polarized antenna is formed by adopting a ridge waveguide wide side to open a longitudinal slit.
Furthermore, the horizontal polarization antenna and the vertical polarization antenna are respectively composed of 64 line sources, and when the antenna is transmitted, the antenna is transmitted in a constant amplitude by a middle 48 line source, and when the antenna is received, the antenna is received by a 64 line source.
Furthermore, the waveguide slot planar antenna array consists of 8 groups of sub-array antennas, and each group of sub-array antennas comprises 8 wide-edge longitudinal slot line sources and 8 narrow-edge slot line sources.
Further, the DTRU subsystem comprises 17 DTRU modules, each DTRU module comprises 8 channels, and radio frequency channels, a digital board and corresponding electrical interconnection interfaces and mechanical installation interfaces are contained in each DTRU module, wherein the radio frequency channels and the digital board can be separated.
Furthermore, the digital beam forming/signal processing subsystem is composed of a digital waveform generating module, a digital intermediate frequency receiving and processing module, a digital beam forming module, a digital pulse compression module, a doppler signal processing module and an optical transmission and timing synchronization processing module, wherein the digital waveform generating module and the digital intermediate frequency receiving and processing module are integrated in the DTRU module.
Furthermore, the radar also comprises a blind complementing mode for solving the detection blind area, wherein the blind complementing mode adopts time division blind complementing or frequency division blind complementing;
the time division blind compensation adopts the alternative transmission of wide and narrow pulse groups among pulses to solve the detection blind area, the wide pulse detects the echo of the far area, the narrow pulse carries out blind compensation processing on the wide pulse detection blind area, splicing processing is carried out by utilizing the detection data of two times, and the time division mode realizes the blind compensation processing;
the frequency division blind-repairing method adopts the intra-pulse transmission of wide and narrow pulses with different frequencies to solve the detection blind area, adopts the intra-pulse transmission of double-frequency digital waveforms, firstly transmits the wide pulse and then transmits the narrow pulse, the wide and narrow pulses adopt different frequencies in the intra-pulse, digital receiving channels are separated through different digital filters, separated narrow pulse echo signals and wide pulse echo signals after digital pulse compression processing are output to a Doppler signal processing unit to be processed, and detection distance blind-repairing processing is realized in an intra-pulse frequency division mode.
The time division blind complementing adopts the way that wide and narrow pulse groups are alternately transmitted among pulses to solve a detection blind area, the wide pulses detect far-zone echoes, the narrow pulses carry out blind complementing processing on the wide pulse detection blind area, the interval time of the wide and narrow pulses is pulse cumulative number (32, 64, 128 and 256 are optional), splicing processing is carried out by using twice detection data, and the time division mode realizes the blind complementing processing;
the frequency division blind-repairing method adopts the intra-pulse transmission of wide and narrow pulses with different frequencies to solve a detection blind area, adopts the intra-pulse transmission of double-frequency digital waveforms, firstly transmits the wide pulses and then the narrow pulses, the transmission interval of the wide and narrow pulses is less than 1 mu s, the wide and narrow pulses adopt different frequencies in the pulse, digital receiving channels are separated through different digital filters, separated narrow pulse echo signals and wide pulse echo signals after digital pulse compression processing are output to a Doppler signal processing unit to be processed, and detection distance blind-repairing processing is realized in an intra-pulse frequency division mode.
Furthermore, the radar also comprises a method for correcting the emission gain and the emission beam width, which comprises the following steps:
step 1: calculating the antenna beam width as:
wherein: theta is the off-normal angle;
λ is the wavelength;
d is the line source distance;
I n for the nth path of electric field intensity
And 2, step: the antenna gain is calculated from equation (1) as:
wherein: theta.theta. t Is the horizontal beam width;
and 3, step 3: calculating the change of the antenna receiving beam direction diagram caused by the gain change of the receiving channel as follows:
P(θ)＝|W H a(θ)|……(3)
wherein, P (theta) is an array antenna directional diagram; w is the weight vector of the array, W H Represents a conjugate transpose; a (θ) is a unit factor;
and 4, step 4: calculating the beam width change and the gain change of the phase scanning antenna as follows:
wherein:
is the vertical beam width;
delta delta is the angle of elevation from the normal
X＝1 Δδ≤30°
X＝1.5 30≤Δδ≤40°
X＝2 40≤Δδ≤50°
X＝3 50≤Δδ≤60°。
The invention has the beneficial effects that:
1. and a full-digital dual-polarization phased array system is adopted, the polarization mode is flexible and controllable, and any polarization can be realized.
2. The wide-emission narrow-emission multi-beam system is adopted, the detection period is shortened, the data rate is high, and the dangerous weather capturing capability is strong.
3. By adopting different-frequency multi-beam scanning, the meteorological echo structure for reducing interference among beams is clear.
4. And the detection data quality is improved by adopting online automatic amplitude-phase correction and complete online radar calibration.
5. And a digital active phased array is adopted, so that the reliability is high, and the maintenance cost of the whole life cycle is low.
6. The broadband active phased array antenna has a multi-frequency-point frequency hopping working mode and is high in interference resistance.
Drawings
FIG. 1 is a general schematic of the present invention;
FIG. 2 is a schematic plan view of a waveguide split planar antenna array;
FIG. 3 is a cross-sectional view of FIG. 2 taken in a vertical direction;
FIG. 4 is a side view of a waveguide split planar antenna array;
FIG. 5 is a schematic diagram of a DTRU subsystem;
FIG. 6 is a block diagram of a Digital Beam Forming (DBF)/signal processing subsystem;
FIG. 7 is a schematic diagram of Digital Beam Forming (DBF)/signal processing subsystem signal processing;
figure 8 is a functional block diagram of a Digital Beam Forming (DBF) extension;
FIG. 9 is a diagram of the operation principle and process flow of a Digital Beam Forming (DBF)/signal processing subsystem;
FIG. 10 is a schematic block diagram of a timing synchronization subsystem and network components;
FIG. 11 is a schematic diagram of a wide-narrow pulse group of time-division complementary blind alternating transmission
Fig. 12 is a schematic diagram of frequency-division blind-compensation wide-narrow pulse transmission.
Detailed Description
The technical solutions of the present invention are further described in detail below with reference to specific examples, but the scope of the present invention is not limited to the following.
As shown in fig. 1, a dual polarization phased array weather radar includes:
a waveguide split plane antenna array is formed by alternately configuring a horizontal polarization antenna and a vertical polarization antenna;
the DTRU subsystem is composed of a DTRU module and a heat radiation fan;
a digital beam forming/signal processing subsystem consisting of a signal processing module, an optical transmission module and a timing synchronization module;
a servo subsystem, a frequency source and distribution network subsystem and a monitoring subsystem;
when transmitting, presetting phase and amplitude according to amplitude and phase control words in a digital waveform generation module DDS in the full array plane DTRU module when combining a clock and a timing signal to generate a waveform, and directionally radiating a transmitting beam to a designated airspace through a waveguide fracture plane antenna array;
during receiving, the waveguide split plane antenna array receives the reflected electromagnetic wave signals in the airspace, forms digital orthogonal signals after processing, sends the digital orthogonal signals to the digital beam forming subsystem, and generates any receiving beam in the scanning airspace according to the digital orthogonal signals of the full array surface.
As a preferred embodiment, the horizontally polarized antenna is formed by opening an oblique slit 3 on the narrow side 1 of the ridge waveguide, and the vertically polarized antenna is formed by opening a longitudinal slit 4 on the wide side 2 of the ridge waveguide, and the structure can be seen in fig. 2. The horizontal polarization antenna and the vertical polarization antenna are respectively composed of 64 line sources, and when the antenna is transmitted, the antenna is transmitted in equal amplitude by a middle 48 line source, and when the antenna is received, the antenna is received by the 64 line source. The waveguide split planar antenna array consists of 8 groups of sub-array antennas, and each group of sub-array antennas comprises 8 wide-edge longitudinal slit line sources and 8 narrow-edge slit line sources. A plurality of oblique slits 3 are sequentially arranged on the narrow side 1 of the ridge waveguide along the axial direction and used as a horizontal polarization antenna; the ridge waveguide wide edge 2 is sequentially provided with a plurality of longitudinal seams 4 along the axial direction to be used as a vertical polarization antenna; the horizontally polarized antennas and the vertically polarized antennas are alternately arranged to form a ridge waveguide slot planar antenna array. The distance between the adjacent oblique slits 3 on the narrow edge 1 of the ridge waveguide is 20.8 +/-0.02 mm, and the number of the oblique slits 3 is 80. The distance between the longitudinal seams 4 is 22.1 +/-0.02 mm, the width of the longitudinal seams 4 is 1.7 +/-0.02 mm, the length of the longitudinal seams 4 is 76, and the number of the longitudinal seams 4 is 76. The longitudinal slits 4 are distributed along the wide side 2 of the ridge waveguide in an axially staggered manner, and the offset is 0.02m. One end of each of the narrow edge 1 and the wide edge 2 of the ridge waveguide is connected with a coaxial connector 5, and the other end of each of the narrow edge and the wide edge is connected with a coaxial load 6, and the structure can be seen in fig. 3 and 4.
If the vertical plane needs to meet the requirement of phase scanning +/-18 degrees, the one-dimensional phase scanning dual-polarization phased array antenna is calculated according to theory, and the distance between the antenna units is 23mm. I.e. neither the horizontally polarized nor the vertically polarized antenna element spacing can be larger than 24mm. Because the two antennas are alternately arranged, the sum of the external dimensions of the two waveguides can not exceed 24mm according to the non-interval arrangement of the two antennas. In the X wave band, there are usually standard waveguides of BJ84 and BJ100 specifications, and if a smaller BJ100 type waveguide is selected, the waveguide size is 22.86mm × 10.16mm × 1mm. The wide sides and narrow sides of the waveguides are arranged alternately with a spacing of 37.02mm. This spacing is much larger than the required cell spacing, so that the antenna line source has not been able to select a conventional standard waveguide, and the waveguide size has to be compressed.
The single ridge waveguide is characterized in that a raised ridge is arranged in the middle of the waveguide, and compared with a rectangular waveguide, due to the flange capacitance effect of the ridge waveguide, the cut-off wavelength of the TE10 wave is longer than that of the TE10 wave in the rectangular waveguide, so that the required waveguide size can be obtained by compressing the width size. The dimension of the narrow-edge linear source single-ridge waveguide is finally determined to be 18mm multiplied by 7.2mm multiplied by 1mm by balancing processing and design. The broadside line source single ridge waveguide dimensions were 11.7mm by 9.5mm by 1mm. The distance between the two waveguides is 18.9mm, and the requirement of the antenna unit distance of 24mm can be met.
As a preferred embodiment, the DTRU subsystem includes 17 DTRU modules, each DTRU module includes 8 channels, including a radio frequency channel, a digital board, and corresponding electrical interconnection interfaces and mechanical installation interfaces, wherein the radio frequency channel and the digital board are detachable, and the structure principle thereof can be described with reference to fig. 5.
The DTRU module radio frequency channel mainly completes the amplification and frequency mixing of the transmitting intermediate frequency signal and the filtering, frequency mixing and amplification of the receiving signal. The digital channel completes the generation of a transmitting signal and the digital quadrature down-conversion of a receiving signal. The power conversion unit completes voltage conversion and voltage and current monitoring. The power division board divides the signal of the input component and outputs the signal to the digital DTRU. The main functions include:
a) And (3) a transmitting function: receiving control signals such as local oscillation signals, AD clocks, DDS clocks, synchronous signals and the like, and finishing signal generation, up-conversion, initial phase compensation of components and power amplification according to the requirements of a specified working mode;
b) A receiving function: receiving a radio frequency weak signal, carrying out amplification, filtering, down-conversion, quantization and other processing, packaging the I/Q digital orthogonal signal, and outputting the packaged I/Q digital orthogonal signal through an optical link (including a simultaneous multi-frequency point receiving state);
c) The monitoring and calibration function can control the operation or non-operation of any transceiving channel, and realize transceiving test and calibration of each channel component;
d) Monitoring the working state of a transmitting channel in the module in real time and outputting a BITE signal; positioning module faults to each independent channel and outputting channel fault state information;
e) And (4) protection function: the protection functions of over-pulse width, over-repetition frequency, over-duty ratio, overvoltage, over-temperature and the like are realized;
f) The correction function of the synchronous signal is provided;
g) The module has fault isolation capability, and the fault of any channel does not influence the normal work of other channels;
h) The module is preset with a software debugging port, and the program can be upgraded without disassembling the module.
As shown in fig. 6, the digital beam forming/signal processing subsystem is composed of a digital waveform generating module, a digital if receiving processing module, a digital beam forming module, a digital pulse compressing module, a doppler signal processing module, and an optical transmission and timing synchronization processing module, wherein the digital waveform generating module and the digital if receiving processing module are integrated in the DTRU module.
Further, the digital beam forming module comprises a transmitting beam forming part and a receiving beam forming part. The DTRU scheme is adopted in the system, so that a complex power division phase shift network at the front end of the traditional analog system can be omitted, and meanwhile, a receiving and transmitting front end feed system is simple, and non-ideal factors are greatly reduced. The beam correction of the system is completed through digital processing, and the system has the advantages of flexible energy distribution, strong adaptive capacity, high precision and high reliability. All-optical interconnection is adopted for data communication of a Digital Beam Forming (DBF)/signal processing subsystem, and all uplink and downlink data streams and radar complete machine control information are transmitted through optical fibers. The data interconnection and intercommunication among the modules are connected through single-mode double-fiber optical fibers, the wiring network and logic inside the system are clear and simple, the sexuality index of the whole radar is greatly improved, the use, maintenance and repair are convenient, and the system composition block diagram is shown as 6.
The Digital Beam Forming (DBF)/signal processing subsystem is divided into: digital waveform generation (DDS), digital intermediate frequency acquisition, digital Beam Forming (DBF) and digital pulse compression processing (DPC), a timing and synchronous processing module, multi-channel Doppler signal processing and the like. The digital acquisition part is formed by distributing a plurality of acquisition board cards, a single board card integrates 8 acquisition channels, all-optical communication is adopted between the acquisition board and a digital beam forming and digital pulse compression processing board, a single digital beam forming and digital pulse compression processing unit corresponds to the input of 16 (128) acquisition board cards, the digital beam forming and digital pulse compression processing points part of data output by the digital acquisition part into a beam, performs pulse compression processing, outputs processed IQ data to a data synthesis and transmission processing unit for final beam forming processing and packaging and transmitting to multi-channel Doppler signal processing; the multichannel Doppler signal processing is used for completing multichannel Doppler parameter processing, and a processing result is output to a data acquisition system, and a signal processing connection schematic diagram is shown as 7.
The digital waveform generation and digital intermediate frequency receiving processing part is integrated in the DTRU and mainly completes intermediate frequency excitation generation, echo intermediate frequency sampling, digital intermediate frequency processing, coherent processing, IQ data optical fiber transmission and conversion. The functions are as follows:
a) The analog intermediate frequency is converted to a digital intermediate frequency process and a quadrature signal or intermediate result of the process is output.
b) And filtering and separating the frequency-division beam echoes to generate a plurality of paths of independent IQ signals.
c) And performing amplitude-phase initial correction on the echo by using the correction information.
d) And realizing the phase weighting of the output excitation signal by utilizing the wave control information.
e) And generating a digital arbitrary waveform, generating a transmitting excitation intermediate frequency pulse, simultaneously generating intermediate frequency analog and test signals, and supporting arbitrary amplitude modulation, phase modulation, frequency modulation and combination.
f) And the detection of the internal temperature, the real-time voltage detection, the front-end RF reference clock and the like of the module is completed.
g) The BITE detection of the module is completed.
Each path of digital waveform generation and digital intermediate frequency receiving complete one path of intermediate frequency excitation output and one path of intermediate frequency echo receiving processing, and simultaneously provide timing and synchronization with high stability and low phase noise for the integrated radio frequency front end. And receiving a DBF control signal from a terminal, completing corresponding working mode switching and transmitting beam phase shift control, finally outputting an IQ signal with corresponding frequency, and transmitting the IQ signal to a DBF processor through a single-mode optical fiber. The system has 129 digital receiving modules and 97 paths of strip waveform excitation output, wherein 32 paths are pure receiving channels. All control and state signals of the module, such as monitoring information, time information and the like, are packaged together with IQ data and transmitted to a Doppler signal processor through an optical fiber.
The intermediate frequency excitation waveform can be uploaded through a waveform data file, and a user can select a proper waveform file according to needs to generate a required waveform form, a required pulse width and a required pulse pressure ratio.
The digital beam forming part is divided into two parts of transmitting beam forming and receiving beam forming.
The transmitting beam forms and controls 96+1 paths of transmitting channels, the phase shift code of each transmitting beam is sent to each digital intermediate frequency receiving channel, and various phase-shifted excitation signals are generated in the DDS. Because the system adopts a time division transmission multi-beam mode, in order to reduce the blind area of the first transmission pulse echo as much as possible, the transmission beam forming is required to have very quick phase distribution capability and frequency switching capability, and the switching of the beam forming is completed within the sub-microsecond time between two adjacent pulses. The blind area caused by beam switching is greatly shortened. The optical fiber only transmits digital information, and signals such as phase shift control, synchronous triggering and the like are electrically transmitted.
The DBF extension is mainly composed of an optical fiber signal interface board, a signal processing board, a timing and interface control board, a VPX chassis (including a power supply and a fan), a VPX main board, a digital signal test source module, and the like, and a schematic diagram thereof is shown in fig. 8.
Doppler signal processing
The number of echo beams of the radar system is 20 at most, the processing capacity and the data volume of the radar system are 20 times of those of a general Doppler signal processor, and the consumption of hardware resources is very large. In design, a high performance server is employed. The processing algorithms to be completed by the signal processor include clutter cancellation, FFT transformation and related operations, data communication, fault detection and the like. The design configuration of the system hardware resources can meet the operation amount requirement of the adopted high-performance algorithm and leave proper allowance, so that the method is convenient to be upgraded into a more complex algorithm in the future and supports more beam number processing. All-optical communication is adopted between the Doppler signal processing and the DBF processor, and the processing mode supports multiple processing modes such as PPP and FFT and the output of multiple processing results.
The Doppler signal processing adopts a general server architecture platform, the mode of the existing signal processing system defined by hardware is eliminated, the decoupling degree of software and hardware is improved to the maximum extent, the software and the hardware are upgraded and maintained independently, all functions required by the system are defined by software, and the function expansion is flexible.
Calibration and synchronization processing unit
In the DBF processor, a calibration/synchronization control unit is also configured, and the unit can independently perform calibration control of transmitting and receiving when the system performs amplitude and phase calibration of the DTRU, store calibration result data, correct transmitting beam forming data and receiving beam forming data and eliminate the influence of amplitude and phase errors and the like on beam forming.
Principle of operation
The radar has 128 rows of antennas in elevation, wherein 96 rows are transmitted, 128 rows are received, and the working principle and the flow of a Digital Beam Forming (DBF)/signal processing subsystem are as follows:
a) The terminal control system transmits various system control commands to a Doppler signal processing module (the module consists of a high-performance server) through an optical fiber;
b) The Doppler signal processing module transmits the command to the data synthesis and transmission processing module through an optical fiber, and then the command is transmitted to each DTRU through the Digital Beam Forming (DBF) and digital pulse compression processing (DPC) module;
c) Under the control of a system wave control command and a timing sequence, the DTRU generates a corresponding digital transmitting signal by a reference clock which is comprehensively transmitted by frequency, converts the digital transmitting signal into radio frequency by up-conversion and radiates the radio frequency by an antenna;
d) The antenna receives radar echo reflected by a cloud and rain target, the radar echo is converted into a digital signal through a digital intermediate frequency receiving and processing module in the DTRU, and the digital signal is transmitted to a post-stage Digital Beam Forming (DBF) and digital pulse compression processing (DPC) module through a high-speed optical fiber;
e) The Digital Beam Forming (DBF) and digital pulse compression processing (DPC) module processes 128 paths of baseband I/Q data into at most 20 paths of receiving beams and transmits the receiving beams to the data synthesis and transmission processing module, the data synthesis and transmission processing module simultaneously receives time information input by the GPS time service system, and the time information is transmitted to the Doppler signal processing module through an optical fiber after data synthesis;
f) The Doppler signal processing module completes processing of at most 20 paths of meteorological echo signals and outputs the meteorological echo signals to the data acquisition and processing subsystem.
The operation principle and the processing flow chart of the Digital Beam Forming (DBF)/signal processing subsystem are shown in fig. 9.
The optical fiber transmission network is a control command and data transmission core of the whole radar system, and mainly has the functions of receiving various instructions of a main control computer and distributing the instructions to various modules, and data exchange and state information return among the modules. The optical transceiver module positioned on the array surface receives various control commands which are processed by Doppler signals and transmitted from a terminal computer, and the DBF and digital pulse compression processing module distributes the control commands to each DTRU unit, the calibration module and the timing synchronization module of the array surface; and simultaneously, receiving data and state information of each DTRU, the calibration module and the timing synchronization, packing the data and the state information by the DBF and digital pulse compression processing module, and transmitting the packed data and the state information to the Doppler signal processing unit under the array surface through the optical transceiver module. The modules are communicated by adopting single-mode bidirectional optical fibers, and meanwhile, the optical fiber transmission network only transmits control commands, data and state signals and does not transmit synchronous signals and clock signals, so that the high-speed and high-capacity transmission requirements of the system can be met, and the reliability of the whole system can be improved.
The timing synchronization subsystem and the network mainly complete the generation of clock signals, high-precision timing and synchronous signals and control the synchronous coordination work of all the constituent systems of the radar array surface. A schematic block diagram of the timing synchronization subsystem and the network is shown in fig. 10. When the timing synchronization module works, the timing synchronization module receives various control instructions forwarded by the DBF and the digital pulse compression processing module, generates synchronization signals and time sequence control signals required by each functional module according to the instructions, and controls each system of the radar to normally work according to the command of the main control computer. The timing synchronization module and the frequency synthesis module are arranged on an antenna array surface, and a hardware direct connection mode rather than an optical transmission re-decoding mode is adopted for clock, timing and synchronization required by the whole machine, so that the whole system can work stably and reliably.
The antenna servo subsystem completes two functions of antenna azimuth mechanical rotation and pitching mechanical rotation. The system comprises an azimuth motor, an azimuth reducer, an azimuth rotary transformer, a pitching electric actuating mechanism, an azimuth locking structure, a servo drive and the like.
An AC servo system is adopted, and an AC brushless servo motor is used as an actuating motor for driving an azimuth axis of the antenna. The AC brushless servo motor has good speed regulation characteristic and linear mechanical characteristic, no commutating brush, no maintenance, very small output power, small size, light weight and other advantages.
The pitching mechanical rotation of the antenna is completed by adopting a pitching electric actuating mechanism, the overturning is realized by a servo electric cylinder of the pitching mechanical actuating mechanism, and position closed-loop control is formed by utilizing an encoder in the pitching rotation process.
The main monitor controls the azimuth driver and the pitching driver to move through the RS-422 and the RS-485 respectively;
the azimuth rotary change signal, the upper limit and the lower limit of the pitching electric actuating mechanism are close to the switch signal, and the pitching angle detection encoder signal directly enters the main monitoring; azimuth rotation signal: four signal lines (COS +, COS-, SIN +, SIN-).
Proximity switch signal: a switch signal is transmitted through a signal wire (the approach switch is conducted to output +12V, and the approach switch is disconnected to output 0V);
encoder signal: the encoder transmits data via RS-485 communication.
The servo control panel is communicated with the main monitor through RS-485, and reports the state information of the pitching lock, the pitching proximity switch and the pitching angle code to the main monitor. The main monitor sends a locking instruction to the servo control board. In addition, when the antenna is removed, the antenna is removed in place, and the main monitor needs to inform the servo system so as to carry out subsequent work.
Finally, the frequency source and distribution network subsystem is mainly composed of a frequency source, 2 clock power distribution networks, 2 local oscillator power distribution networks, 1 test calibration power distribution network, and a calibration attenuator, and the structure thereof can be referred to fig. 1. The remote control of the monitoring subsystem on the whole radar comprises multiple controls on a power distribution system, a servo system, a receiving system and the like. A user can realize full-function remote control operation on the whole radar through the monitoring subsystem.
Furthermore, the radar also comprises a blind-compensating mode for solving the detection blind area, wherein the blind-compensating mode adopts time-division blind-compensating or frequency-division blind-compensating;
as shown in fig. 11, time division blind compensation adopts alternate emission of wide and narrow pulse groups between pulses to solve detection blind areas, wide pulses detect far-zone echoes, narrow pulses perform blind compensation processing on the wide pulse detection blind areas, two times of detection data are used for performing splicing processing, and a time division manner realizes blind compensation processing;
as shown in fig. 12, the frequency division blind repair adopts intra-pulse transmission of wide and narrow pulses with different frequencies to solve the blind detection area, adopts intra-pulse transmission of dual-frequency digital waveforms, first transmits the wide pulse and then transmits the narrow pulse, the wide and narrow pulses adopt different frequencies in the intra-pulse, digital receiving channels are separated through different digital filters, the separated narrow pulse echo signal and the wide pulse echo signal compressed by the digital pulse are output to a doppler signal processing unit for processing, and the intra-pulse frequency division mode realizes the detection distance blind repair processing.
Time division blind compensation adopts the alternative transmission of wide and narrow pulse groups among pulses to solve the detection blind area, the wide pulse detects the echo of a far zone, the narrow pulse carries out blind compensation processing on the wide pulse detection blind area, the interval time of the wide and narrow pulse is the pulse cumulative number (32, 64, 128 and 256 are optional), splicing processing is carried out by utilizing the two times of detection data, and the blind compensation processing is realized in a time division mode;
the frequency division blind-repairing method adopts the intra-pulse transmission of wide and narrow pulses with different frequencies to solve the detection blind area, adopts the intra-pulse transmission of double-frequency digital waveform, firstly transmits the wide pulse and then transmits the narrow pulse, the transmission interval of the wide and narrow pulses is less than 1 mu s, the wide and narrow pulses adopt different frequencies in the pulse, digital receiving channels are separated through different digital filters, the separated narrow pulse echo signal and the wide pulse echo signal after the digital pulse compression processing are output to a Doppler signal processing unit for processing, and the intra-pulse frequency division mode realizes the detection distance blind-repairing processing.
Furthermore, the radar also comprises a method for correcting the emission gain and the emission beam width, which comprises the following steps:
step 1: calculating the antenna beam width as:
wherein: theta is the off-normal angle;
λ is the wavelength;
d is the line source spacing;
I n for the nth path of electric field intensity
Step 2: the antenna gain is calculated from equation (1) as:
wherein: theta t Is the horizontal beam width;
and step 3: calculating the change of the antenna receiving beam direction diagram caused by the gain change of the receiving channel as follows:
P(θ)＝|W H a(θ)|……(3)
wherein, P (theta) is an array antenna directional diagram; w is the weight vector of the array, W H Represents a conjugate transpose; a (theta) is a unit factor;
and 4, step 4: calculating the beam width change and the gain change of the phase-scanning antenna as follows:
G＝G 0 +10Xlog(cosΔδ)……(5)
wherein:
is the vertical beam width;
delta delta is the angle of elevation from the normal
X＝1 Δδ≤30°
X＝1.5 30≤Δδ≤40°
X＝2 40≤Δδ≤50°
X＝3 50≤Δδ≤60°。
The foregoing is illustrative of the preferred embodiments of this invention, and it is to be understood that the invention is not limited to the precise form disclosed herein and that various other combinations, modifications, and environments may be resorted to, falling within the scope of the concept as disclosed herein, either as described above or as apparent to those skilled in the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the invention as defined by the appended claims.
Claims (7)
1. A dual polarization phased array weather radar, comprising:
a waveguide split plane antenna array is formed by alternately configuring a horizontal polarization antenna and a vertical polarization antenna;
the DTRU subsystem is composed of a DTRU module and a heat radiation fan;
a digital beam forming/signal processing subsystem consisting of a signal processing module, an optical transmission module and a timing synchronization module;
a servo subsystem, a frequency source and distribution network subsystem and a monitoring subsystem;
when transmitting, the DDS in each DTRU module of the full array plane generates an excitation signal according to a designated amplitude and phase control word and combines a clock and a timing signal to generate a transmission, the excitation signal is input into the antenna units through up-conversion and power amplification, and each antenna unit generates a corresponding polarized electromagnetic wave to radiate to a designated airspace for power synthesis to form a transmission beam;
when receiving, the waveguide slot plane antenna array sends the reflected electromagnetic wave signals in a receiving airspace to a DTRU module, the signals are down-converted to intermediate frequency after being amplified by low noise, the intermediate frequency signals are processed by A/D sampling and digital down-conversion to generate digital orthogonal video signals I/Q and are sent to a digital beam forming system, and the digital beam forming system arbitrarily forms required receiving beams in the scanning airspace through the weighting control of the amplitude and the phase of each channel signal;
the blind-compensating mode is used for solving the detection blind area, and adopts time division blind-compensating or frequency division blind-compensating;
the time division blind compensation adopts the alternative emission of wide and narrow pulse groups among pulses to solve a detection blind area, the wide pulse detects a far-zone echo, the narrow pulse carries out blind compensation processing on the wide pulse detection blind area, the interval time of the wide and narrow pulses is pulse cumulant, splicing processing is carried out by utilizing twice detection data, and the blind compensation processing is realized in a time division mode;
the frequency division blind complementing method adopts the intra-pulse transmission of wide and narrow pulses with different frequencies to solve the detection blind area, adopts the intra-pulse transmission of double-frequency digital waveforms, firstly transmits the wide pulses and then transmits the narrow pulses, the transmission interval of the wide and narrow pulses is less than 1 mu s, the wide and narrow pulses adopt different frequencies in the pulse, digital receiving channels are separated through different digital filters, the separated narrow pulse echo signals and the wide pulse echo signals after digital pulse compression processing are output to a Doppler signal processing unit for processing, and the intra-pulse frequency division mode realizes the detection distance blind complementing processing.
2. The dual polarization phased array weather radar of claim 1, wherein the horizontally polarized antenna is formed by making an oblique slot (3) with a ridge waveguide narrow side (1), and the vertically polarized antenna is formed by making a longitudinal slot (4) with a ridge waveguide wide side (2).
3. The dual-polarization phased array weather radar of claim 2, wherein the horizontally polarized antenna and the vertically polarized antenna are each comprised of 64 line sources, and transmit at equal amplitude from a middle 48 line source, and receive at 64 line sources.
4. The dual-polarization phased array weather radar of claim 3, wherein the waveguide slot plane antenna array is comprised of 8 sets of sub-array antennas, each set of sub-array antennas comprising 8 broadside longitudinal slot line sources and 8 narrow-side slot line sources.
5. The dual polarization phased array weather radar of claim 1, wherein the DTRU subsystem includes 17 DTRU modules, each DTRU module including 8 channels, including a radio frequency channel, a digital board, and corresponding electrical interconnect interface and mechanical mounting interface, wherein the radio frequency channel and the digital board are detachable.
6. The dual polarization phased array weather radar of claim 5, wherein the digital beam forming/signal processing subsystem is comprised of a digital waveform generation module, a digital intermediate frequency reception processing module, a digital beam forming module, a digital pulse compression module, a Doppler signal processing module, and a light transmission and timing synchronization processing module, wherein the digital waveform generation module and the digital intermediate frequency reception processing module are integrated in the DTRU module.
7. The dual polarization phased array weather radar of any one of claims 1 to 6, wherein the radar further comprises a transmit gain, transmit beam width correction method, comprising the steps of:
step 1: calculating the antenna beam width as:
wherein: theta is the off-normal angle;
λ is the wavelength;
d is the line source distance;
I n the nth path of electric field intensity;
and 2, step: the antenna gain is calculated from equation (1) as:
wherein: theta.theta. t Is the horizontal beam width;
and 3, step 3: calculating the change of the digital receiving beam direction diagram caused by the gain change of the receiving channel as follows:
P(θ)＝|W H a(θ)|……(3)
wherein, P (theta) is an array antenna directional diagram; w is the weight vector of the array, W H Represents a conjugate transpose; a (θ) is a unit factor;
and 4, step 4: calculating the change of the phase scanning beam width and the gain change of the antenna as follows:
G＝G 0 +10X log(cosΔδ)……(5)
wherein:
is the vertical beam width;
delta delta is the angle of elevation from the normal
X＝1，Δδ≤30°；
X＝1.5，30°≤Δδ≤40°；
X＝2，40°≤Δδ≤50°；
X＝3，50°≤Δδ≤60°。
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| CN112505707B (en) * | 2021-01-29 | 2021-06-01 | 成都远望探测技术有限公司 | X-waveband dual-polarization rapid scanning phased array weather radar |
| CN112986969A (en) * | 2021-02-10 | 2021-06-18 | 南京恩瑞特实业有限公司 | One-key startup and shutdown system of phased array weather radar |
| CN112986917A (en) * | 2021-02-10 | 2021-06-18 | 南京恩瑞特实业有限公司 | Automatic writing system of component parameters of phased array weather radar |
| CN113126097B (en) * | 2021-05-07 | 2024-03-26 | 华云敏视达雷达(北京)有限公司 | Meteorological detection method and digital phased array weather radar |
| CN113655455B (en) * | 2021-10-15 | 2022-04-08 | 成都信息工程大学 | Dual-polarization weather radar echo signal simulation method |
| CN113960676B (en) * | 2021-10-22 | 2023-06-16 | 中国地质科学院地球物理地球化学勘查研究所 | FPGA-based time domain aviation electromagnetic multi-wave pulse transmitting device |
| CN113687361B (en) * | 2021-10-26 | 2022-02-18 | 南京恩瑞特实业有限公司 | Simultaneous multi-channel array processing method based on space-time-frequency code wave technology |
| CN114265016B (en) * | 2021-12-28 | 2023-04-14 | 河北德冠隆电子科技有限公司 | Multi-angle adjustment wide area radar sensor system and method |
| CN114779193B (en) * | 2022-06-17 | 2022-11-01 | 成都信息工程大学 | Phased array weather radar echo signal simulation method and device |
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