CN105204023A - Echo signal processing method and device of weather radar system based on continuous wave system - Google Patents
Echo signal processing method and device of weather radar system based on continuous wave system Download PDFInfo
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- CN105204023A CN105204023A CN201510578761.XA CN201510578761A CN105204023A CN 105204023 A CN105204023 A CN 105204023A CN 201510578761 A CN201510578761 A CN 201510578761A CN 105204023 A CN105204023 A CN 105204023A
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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
- G01S7/41—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00 using analysis of echo signal for target characterisation; Target signature; Target cross-section
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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 an echo signal processing method and device of a weather radar system based on a continuous wave system. The echo signal processing method comprises the following steps that A/D conversion is carried out on an echo analog signal to obtain a digital signal; phase detection is carried out on the digital signal to obtain I/Q data; digital de-chirping processing is carried out, and difference frequency echo data are obtained through a distance matching filter; window processing and two-dimensional FFT processing are carried out on the difference frequency echo data in sequence to obtain an echo linear power spectral density distribution; spectral average processing and ground clutter filter processing are carried out on the echo linear power spectral density distribution in sequence, and parameter estimation is carried out on the obtained data to obtain the strength, speed and spectral width data of each range bin. The weather radar based on the continuous wave system can detect the strength, vertical speed and spectral width information of rainfall clouds or rainfall lower than 0.2-24 km in each height layer in real time, and the purpose of refined weather detection is achieved.
Description
Technical field
The present invention relates to weather radar field, be specifically related to a kind of echo signal processing method and device of the weather radar system based on continuous wave system.
Background technology
Measurement Precipitation Clouds or precipitation in the Ground-based remote sensing system of each height layer intensity, vertical speed, spectrum width information, weather radar adopts pulse radar usually, but owing to being subject to the restriction of fire pulse width, the range resolution of pulsed radar is lower, be not suitable for the aerological sounding that becomes more meticulous, be difficult to obtain comparatively accurate aerological sounding data yet.
Summary of the invention
Adopt the weather radar system range resolution of continuous wave system high, relative to traditional pulse regime weather radar, with the obvious advantage in the aerological sounding that becomes more meticulous.The object of the invention is for providing echo signal processing method and device based on the weather radar system of continuous wave system.
For achieving the above object, the invention provides a kind of echo signal processing method of the weather radar system based on continuous wave system, transmitting of described weather radar system adopts linear frequency modulation continuous wave signal, and described echo signal processing method comprises the following steps:
Analogue echoes signal is carried out A/D conversion, obtains echo digital signal;
Described echo digital signal is carried out phase-shift detection, obtains I/Q data;
Described I/Q data are carried out digital deramp processing, then obtains difference frequency echo data by distance matched filter;
Windowing process is carried out to described difference frequency echo data;
First dimension FFT process is carried out to the difference frequency echo data through windowing process, obtains the range distribution characteristic of echo and echo apart from upper intensity PHASE DISTRIBUTION;
Apart from upper intensity PHASE DISTRIBUTION, Two-dimensional FFT process is carried out to described echo, obtains the echo linear power spectral density distribution of each range bin;
Spectrum average treatment is carried out to the echo linear power spectral density distribution of described each range bin;
Land clutter filtering process is carried out to the echo linear power spectral density distribution of each range bin after spectrum average treatment;
Parameter estimation is carried out to the echo linear power spectral density distribution of each range bin successively after spectrum average treatment and filtering process, obtains the intensity of each range bin, speed and spectrum width data.
Preferably, described windowing process step performs one or both window functions that user selects in advance from the window function of the some different secondary lobe degree of suppression preset.
Preferably, described spectrum average treatment adopts incoherent frequency spectrum to accumulate;
Preferably, described land clutter filtering process adopts plug-in type filtering processing mode;
Preferably, described parameter estimation comprises the following steps:
Adopt sliding window method to carry out the search of spectrum peak to the echo linear power spectral density distribution of each range bin, centered by the spectrum peak position searched, carry out the calculating of square parameter to both sides expansion setting range.
Preferably, described echo signal processing method is further comprising the steps of:
To intensity, speed, the spectrum width data acquisition maximum set method of each range bin, linear averaging is carried out to the data in set, reduce data variance;
Echo power correction is carried out according to distance matched filter amplitude versus frequency characte and intensity calibration result.
Preferably, described linear frequency modulation continuous wave signal is linear frequency modulation sawtooth continuous wave signal.
Accordingly, present invention also offers a kind of echo signal processing equipment based on continuous wave system weather radar system, transmitting of described weather radar system adopts linear frequency modulation continuous wave signal, and described device comprises:
A/D converting unit, for analogue echoes signal is carried out A/D conversion, obtains echo digital signal;
Phase-shift detection unit, for described echo digital signal is carried out phase-shift detection, obtains I/Q data;
Deramp processing unit, for described I/Q data are carried out digital deramp processing, then obtains difference frequency echo data by distance matched filter;
Windowing process unit, for carrying out windowing process to described difference frequency echo data;
First dimension fft processing unit, for carrying out the first dimension FFT process to the difference frequency echo data through windowing process, obtains echo apart from upper intensity PHASE DISTRIBUTION;
Second dimension fft processing unit, for carrying out Two-dimensional FFT process to described echo apart from upper intensity PHASE DISTRIBUTION, obtains the distribution of echo linear power spectral density;
Spectrum average treatment unit, for carrying out spectrum average treatment to the echo linear power spectral density distribution of described each range bin;
Filter processing unit, for carrying out land clutter filtering process to the distribution of echo linear power spectral density;
Parameter estimation unit, for carrying out parameter estimation to the echo linear power spectral density distribution after spectrum average treatment and filtering process, obtains the intensity of each range bin, speed and spectrum width data.
Preferably, described windowing process unit comprises:
Select performance element, for selecting one or both window functions to carry out windowing process to described difference frequency echo data from window function unit according to the instruction of user;
Window function unit, comprises the window function of some different secondary lobe degree of suppression.
Preferably, described spectrum average treatment adopts incoherent frequency spectrum to accumulate;
Described land clutter filtering process adopts the mode of plug-in type filtering;
Described parameter estimation unit comprises:
Unit is searched at spectrum peak, for adopting sliding window method to carry out the search of spectrum peak to the echo linear power spectral density distribution of each range bin;
Square parameter calculation unit, for carrying out the calculating of square parameter to both sides expansion centered by the spectrum peak position searched.
Preferably, described echo signal processing equipment also comprises:
Average treatment unit, adopts maximum set method for the intensity to each range bin, speed, spectrum width, carries out linear averaging, reduce data variance to data in set;
Echo power amending unit, for carrying out echo power correction according to distance matched filter amplitude versus frequency characte and intensity calibration result.
Preferably, described linear frequency modulation continuous wave signal is linear frequency modulation sawtooth continuous wave signal.
Beneficial effect of the present invention is as follows:
Echo signal processing method in the present invention and application of installation in the weather radar based on continuous wave system, the employing continuous wave signal that transmits of this weather radar, higher relative to its range resolution of pulse radar, be specially adapted to the aerological sounding that becomes more meticulous.Echo signal processing method in the present invention and the application of device thereof, the weather radar based on continuous wave system is made to can be used in the Precipitation Clouds of measurement 15 ~ 30m highl stratification and the linear power spectral density information of precipitation echo, and can Precipitation Clouds below real-time detection 0.2 ~ 24km height or precipitation in the intensity of each height layer, vertical speed and spectrum width information, achieve the object of the aerological sounding that becomes more meticulous.
Accompanying drawing explanation
Fig. 1 is the theory diagram of an embodiment of weather radar system of the present invention;
Fig. 2 is the theory diagram of an embodiment of weather radar system of the present invention;
Fig. 3 is the theory diagram of an embodiment of weather radar system of the present invention;
Fig. 4 is the equipment appearance schematic diagram of an embodiment of weather radar system of the present invention;
Fig. 5 is the timing diagram of an embodiment of weather radar system control method of the present invention;
Fig. 6 is the structure flow chart of an embodiment of echo signal processing method in the present invention;
Fig. 7 is the structure flow chart of an embodiment of echo signal processing method in the present invention.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
Echo signal processing method and apparatus provided by the invention is used for the weather radar system based on continuous wave system, and please refer to Fig. 1, the described weather radar system based on continuous wave system comprises:
Launch extension set 300, for receiving from the linear frequency modulation continuous wave signal receiving extension set 400 and this signal being carried out obtain continuous wave and transmit after amplifications processes, and continuous wave is transmitted output to emitting antenna module 100;
Receive extension set 400, for output linearity Continuous Wave with frequency modulation signal to transmitting extension set 300, and receive the weather echo signal from receiving antenna module 200, and carry out outputting to digital processing extension set 500 after process is amplified in frequency conversion to described weather echo signal;
Emitting antenna module 100, transmits for launching continuous wave;
Receiving antenna module 200, for receiving weather echo signal;
Digital processing extension set 500, for obtaining weather data information to carrying out signal transacting from the simulating signal receiving extension set, carries out instruction control to radar system state simultaneously.
Further, as shown in Figure 2, Graphics Processing terminal extension set 700 can also be comprised in other preferred embodiments of weather radar system of the present invention, obtain Meteorological Products information for carrying out process to described weather data information, and show described Meteorological Products information.In actual applications, digital processing extension set 500 can be connected by router with Graphics Processing terminal extension set 700, complete internal data and control signal transmission, Graphics Processing terminal extension set 700 can adopt high performance computing machine, not only can complete the real-time display work of Meteorological Products information, the instruction that can also participate in weather radar system controls, the work such as collection, fusion, data prediction of raw data, the omnidistance modal data that user can also be provided to need and intensity, speed, spectrum width information, can browse various non-real-time data.
As shown in Figure 2, in other preferred embodiments of weather radar system of the present invention, the signal processing function of digital processing extension set and instruction monitoring function can be realized respectively by signal transacting extension set 501 and monitoring module 502, signal transacting extension set 501 is mainly used in obtaining weather data information by carrying out signal transacting from the simulating signal receiving extension set, and monitoring module 502 is mainly used in carrying out instruction control and fault collection to radar system state.Certainly, signal transacting extension set 501 and monitoring module 502 also can all be integrated in digital processing extension set 500 as shown in Figure 1.
Concrete, in actual applications, signal transacting extension set 501, monitoring module 502 can be connected by router with Graphics Processing terminal extension set 700, complete internal data and control signal transmission, and system is also by this router shared system data product.Receive extension set 400 to be connected with receiving antenna module phase 200 by corrugated coaxial cable.Launch extension set 300 to be connected with emitting antenna module 100 by corrugated coaxial cable.
In some preferred embodiment of weather radar system of the present invention, described emitting antenna module comprises emitting antenna, the first feed, the first shielding cylinder and first day irdome, and described first shielding cylinder and first day irdome are arranged at above described emitting antenna;
Described receiving antenna module comprises receiving antenna, the second feed, secondary shielding cylinder and the second antenna house, and described secondary shielding cylinder and the second antenna house are arranged at above described receiving antenna.
Described emitting antenna and described receiving antenna adopt the dual paraboloid antenna of bistatic, and take the isolation technology of shielding cylinder, and the isolation between emitting antenna and receiving antenna is at more than 90dB.
Concrete, in actual applications, as shown in Figure 4, described emitting antenna and receiving antenna can be arranged on same platform, and described platform is provided with rigid backbone, and rigid backbone designs according to packaged type, are provided with all devices of radar system.Emitting antenna and receiving antenna are all provided with antenna levelling device, two antennas can be made to be in same level by regulating.
Due to the continuous wave system that this weather radar system adopts, Received signal strength while transmitting, therefore designs bistatic double antenna form.Radar system devices outside drawing as shown in Figure 4, can be seen in the drawings, and emitting antenna and receiving antenna independently exist, and the two is installed on platform skeleton, can by levelling device by antenna adjustments at same surface level.In order to prevent the leakage transmitted, serious transmitting leakage power can cause receiving extension set and block, launching the noise of extension set and spuious leakage can make the reception extension set end of making an uproar worsen, and the landform clutter that the low elevation angle secondary lobe of antenna receives can have a strong impact on system generation, therefore antenna assembly of the present invention is designed to the antenna system of a high-isolation low far field secondary lobe, and adopts the structure of shielding cylinder to reduce low elevation angle secondary lobe further.
As shown in Figure 3, in some preferred embodiment of weather radar system of the present invention, described transmitting extension set comprises:
Transmitter 301, for receiving from the linear frequency modulation continuous wave signal receiving extension set and transferring signal to front stage power amplifier 302;
Front stage power amplifier 302 and final power amplifier 303, obtain continuous wave and transmit after described linear frequency modulation continuous wave signal being carried out amplification process, and transmitted by described continuous wave and output to emitting antenna module 100;
Described reception extension set comprises:
Frequency source 401 and digital waveform generator 402, for generating positive slope linear FM signal and described positive slope linear FM signal being outputted to upconverter 403, the clock signal that described digital waveform generator receive frequency source sends also generates positive slope linear FM signal under the instruction of digital processing extension set controls;
Upconverter 403 and modulation amplifier module 404, for obtaining linear frequency modulation continuous wave signal by after the frequency conversion of described positive slope linear FM signal, amplification, and flow to transmitter 301 by described linear frequency modulation continuous wave signal;
Low noise amplifier 405, for carrying out low noise amplification by the weather echo signal from receiving antenna module 200 and the signal after amplifying being flowed to low-converter 406;
Low-converter 406, obtains echo signal of intermediate frequency for the signal after amplification is carried out frequency-conversion processing, and described echo signal of intermediate frequency is outputted to digital processing extension set 500.
The product data spatial and temporal resolution of weather radar system preferred embodiment of the present invention is high, detects meticulous.Wherein, spatial resolution can reach 15m, and temporal resolution can reach 1s, and detection blind area is short, without the need to mending blind vein punching.Because transmitting and receiving work simultaneously, there is no detection blind area in theory.
Preferably, in some preferred embodiment of weather radar system of the present invention, described transmitter is solid state transmitter.Adopt all solid-state transmitter, reliability is high, and when dutycycle 100%, emissive power reaches 150W.
Further, described reception extension set also comprises:
Fixed ampllitude amplifier, numerical-control attenuator and calibration switch, the input end of described fixed ampllitude amplifier connects an output terminal of frequency converter 403, the input end of the output termination numerical-control attenuator of described fixed ampllitude amplifier, the output termination calibration switch of numerical-control attenuator, the output terminal of described calibration switch is connected with the input end of described low noise amplifier 405, and described calibration switch is used for selecting whether enter calibration mode.
Receive extension set and can be divided into mode of operation and calibration mode.In the operational mode, the positive slope linear FM signal that frequency source 401 and digital waveform generator 402 generate obtains linear frequency modulation continuous wave signal after upconverter 403 and modulation amplifier module 404 process, and described linear frequency modulation continuous wave signal is delivered to transmitter 301; Under calibration mode, digital waveform generator 402 produces intermediate frequency demarcation signal after upconverter 403 processes, a road radiofrequency signal be coupled in addition through fixed ampllitude amplifier, numerical-control attenuator, last from calibration switch through low noise amplifier 405, low-converter 406 feed-in digital processing extension set 500, this demarcation signal is demarcated weather radar system zero distance, echo strength, distance matched filter amplitude versus frequency characte, speed etc.The result of demarcating gives Graphics Processing terminal extension set, is used for correcting result.
Present invention also offers a kind of control method of the weather radar system based on continuous wave system, details are as follows for this control method:
1) transmit
Frequency source 401 sends a signal to digital waveform generator 402 and produces positive slope linear FM signal, described positive slope linear FM signal obtains chirped rf excitation signal through upconverter 403, modulation amplifier module 404 and gives transmitter 301 after processing successively, and what this chirped rf excitation signal obtained successively after front stage power amplifier 302 and final power amplifier 303 amplify transmit gives emitting antenna module 100 and radiate;
2) Received signal strength
The weather echo signal that receiving antenna module 200 receives is given low-converter 406 process and is obtained echo signal of intermediate frequency after low noise amplifier 405 amplifies, described echo signal of intermediate frequency is sent to digital processing extension set 500 (or the signal transacting extension set 501 in digital processing extension set 500), digital processing extension set 500 completes samples to the A/D of echo signal of intermediate frequency, phase-shift detection, numeral frequency modulation removal, signal after aforementioned processing obtains difference frequency echoed signal again after distance matched filtering process, described difference frequency echoed signal obtains the echo linear power spectral density distribution of each range bin successively after windowing process and FFT process, after spectrum average treatment and filtering process are carried out to the echo linear power spectral density distribution of each range bin, carry out the intensity that parameter estimation can obtain each range bin again, speed and spectrum width data, the intensity of described each range bin, speed and spectrum width data are finally sent to Graphics Processing terminal extension set 700 place.
It is pointed out that above-mentioned to transmit and the process of Received signal strength is carried out simultaneously, there is not dividing of priority.
The echo signal processing method that the embodiment of the present invention provides comprises the following steps:
Analogue echoes signal is carried out A/D conversion, obtains echo digital signal;
Described echo digital signal is carried out phase-shift detection, obtains I/Q data;
Described I/Q data are carried out digital deramp processing, then obtains difference frequency echo data by distance matched filter;
Windowing process is carried out to described difference frequency echo data;
First dimension FFT process is carried out to the difference frequency echo data through windowing process, obtains echo apart from upper intensity PHASE DISTRIBUTION;
Apart from upper intensity PHASE DISTRIBUTION, Two-dimensional FFT process is carried out to described echo, obtains the echo linear power spectral density distribution of each range bin;
Spectrum average treatment is carried out to the echo linear power spectral density distribution of described each range bin;
Land clutter filtering process is carried out to the distribution of echo linear power spectral density;
Parameter estimation is carried out to the echo linear power spectral density distribution after spectrum average treatment and filtering process, obtains the intensity of each range bin, speed and spectrum width data.
Above-described embodiment please refer to Fig. 6, comprises the following steps:
Step 51: the echo signal of intermediate frequency that reception extension set 400 is sent back is carried out A/D and is converted to echo digital signal;
Step 52: described echo digital signal is carried out phase-shift detection and obtains I/Q data; NCO (numerically-controlled oscillator), by the FM signal produced and transmitted waveform is synchronous, carries out phase-shift detection with the echo digital signal after A/D changes;
Step 53: described I/Q data are carried out digital deramp processing, then obtain difference frequency echoed signal and difference frequency echo data by distance matched filter; NCO and DDS (digital waveform generator) synchronous FM signal specifically can be adopted to complete deramp processing, and matched filtering bandwidth is relevant with distance range, can see prior art; The Main Function of distance matched filter suppresses the difference frequency signal outside range, avoids the echo distance when the first dimension FFT process folding and produce false target.
Step 54: windowing process is carried out to described difference frequency echo data;
Step 55: carry out the first dimension FFT process to the difference frequency echo data through windowing process, obtains the range distribution characteristic of echo;
Step 56: carry out Two-dimensional FFT process to the range distribution characteristic of described echo, obtains the echo linear power spectral density distribution of each range bin;
Step 57: spectrum average treatment is carried out to the echo linear power spectral density distribution of described each range bin;
Step 58: land clutter filtering process is carried out to the echo linear power spectral density distribution of each range bin through incoherent frequency spectrum accumulation process;
Step 59: parameter estimation is carried out to the echo linear power spectral density distribution after spectrum average treatment and filtering process, obtains the intensity of each range bin, speed and spectrum width data.
Preferably, in some preferred embodiment of frequently echo signal processing method in the present invention, one or both window functions that user selects in advance from the window function of the some different secondary lobe degree of suppression preset in the windowing process process of step 54, are performed.
The Strength Changes of the meteorological target such as cloud, rain is very large, add the effect of the distance factor, echo strength alters a great deal, and meteorological target strength is also very large with the gradient of height change, for the weather radar of continuous wave system, leak to avoid the first dimension FFT as much as possible and produce false target and affect detection accuracy, need to carry out meticulous weighting design to suppress the secondary lobe of FFT to leak.Classical windowed function has rectangular window, hann window, hamm window and blackman window etc., but the secondary lobe degree of suppression of these window functions is fixing.For radar detection Different periods and place, and lack adaptability and dirigibility under different target condition, windowing can cause main lobe broadening, and the range resolution performance of influential system.In order to take into account secondary lobe rejection and range resolution preferably, also be to adapt to different weather conditions simultaneously, the present embodiment is intended adopting the window function (adopt iterative search algorithm design) optimized, and provides and select for user from the window function of the secondary lobe rejection of 30dB ~ 65dB.Staff can select window function according to the situation of change of described meteorological intensity height when real work, such as when meteorological intensity height change is mild, the window function compared with Sidelobe degree of suppression can be adopted, and meteorological intensity height change violent time, for ensureing measuring accuracy, the window function of high secondary lobe degree of suppression can be adopted.
In practical application, preset not windowing ,-30dB ,-42dB ,-55dB four kinds distance window function, and four kinds of classical window functions, i.e. rectangular window, hann window, hamm window and blackman window.User can select one or two kinds or more kinds of window function to carry out windowing process from above-mentioned window function.Both can be simple distance window function during windowing process, also can be the combination of distance window function and classical window function.
Preferably, in some preferred embodiment of echo signal processing method of the present invention, the described spectrum average treatment of step 57 adopts incoherent frequency spectrum to accumulate.
Preferably, in some preferred embodiment of echo signal processing method of the present invention, step 58 land clutter filtering process carried out to echo linear power spectrum time adopt the mode of plug-in type filtering process.
Antenna beam based on the weather radar system of continuous wave system vertically points into the sky, generally the vertical movement speed of air is less, therefore the meeting of weather echo frequency spectrum and ground-clutter spectrum partly overlap, if simply carry out clutter spectrum to remove, weather echo power loss can be caused, cause there is larger ionization meter error, therefore must compensate echo power, the algorithm of the present embodiment adopts the mode of plug-in type filtering to carry out intensity compensation, is divided into the slip-on filter of two kinds of forms of fixed notch and self-adaptation recess.
Preferably, in some preferred embodiment of echo signal processing method of the present invention, the step of described parameter estimation comprises:
Sliding window method is adopted to carry out the search of spectrum peak to the echo linear power spectral density distribution of each range bin;
The calculating of square parameter is carried out to both sides expansion setting range centered by the spectrum peak position searched.
Preferably, in some preferred embodiment of echo signal processing method of the present invention, described echo signal processing method is further comprising the steps of:
Utilize maximum set method, to intensity, speed, the spectrum width data of each range bin in set, carry out linear averaging, reduce data variance;
Echo power correction is carried out according to distance matched filter amplitude versus frequency characte and intensity calibration result.
Rear class data processing needs a large amount of accumulation to extract to be submerged in the signal receiving extension set thermonoise inside, and data quality control is taked the method for uniform averaging.Uniform averaging makes again maximum set average, for the uniform averaging method of uprush, first set consistance window width, discrete sample is rejected, the sample fallen within the scope of this window width is averaged and obtains Output rusults, the variance of result can be reduced so further, improve precision.Adopt the method for quality control, when falling into, the sample size in window width is very few simultaneously, and namely mean that echo dispersion is too large, signal to noise ratio (S/N ratio) is too low, and result is invalid.
The preferred embodiment of the invention described above echo signal processing method please refer to Fig. 7, comprises the following steps:
Step 501: the echo signal of intermediate frequency that reception extension set is sent back is carried out A/D and is converted to echo digital signal;
Step 502: described echo digital signal is carried out phase-shift detection and obtains I/Q data;
Step 503: described I/Q data are carried out deramp processing, then obtain difference frequency echo data by distance matched filter;
Step 504: windowing process is carried out to described difference frequency echo data;
Step 505: carry out the first dimension FFT process to the difference frequency echo data through windowing process, obtains the range distribution characteristic of echo;
Step 506: carry out Two-dimensional FFT process to the range distribution characteristic of described echo, obtains the echo linear power spectral density distribution of each range bin;
Step 507: incoherent frequency spectrum accumulation is carried out to the echo linear power spectral density distribution of described each range bin;
Step 508: plug-in type filtering process is carried out to the distribution of echo linear power spectral density;
Step 509: adopt sliding window method to carry out the search of spectrum peak to the echo linear power spectral density distribution of each range bin;
Step 510: carry out the calculating of square parameter to both sides expansion setting range centered by the spectrum peak position searched, avoid calculating square parameter in whole frequency domain, improve sensitivity, and obtain intensity, speed, the spectrum width data of each range bin;
Step 511: utilize maximum set method, carries out linear averaging to the intensity of each range bin in set, speed, spectrum width data, reduces data variance, and plays quality control effect;
Step 512: carry out echo power correction according to distance matched filter amplitude versus frequency characte and intensity calibration result;
Step 513: afterproduct process.
Obtain can also performing afterproduct process after basic product data through step 512, improve product information further.
In actual applications, step 501 ~ step 506 is performed by signal transacting extension set 501, and step 507 ~ step 513 is performed by Graphics Processing terminal extension set 700.Echo linear power spectrum is transferred to Graphics Processing terminal extension set 700 by kilomega network, Graphics Processing terminal extension set 700 is successively through spectrum average treatment and land clutter filtering process, finally carry out parameter estimation and obtain each range bin intensity, speed, spectrum width data, and product is shown to user the most at last.
The function such as generation and display of the control of radar system, management and base data product is responsible for by Graphics Processing terminal extension set 700, is the direct user oriented window of radar.User can implement radar state control operation, malfunction monitoring and location by Graphics Processing terminal extension set 700, and pass through, to the calculation process of the master data that radar obtains, to complete the real-time display of the basic products such as the intensity of meteorological element, radial velocity and spectrum width, non real-time display and raw data storage etc.
Preferably, described linear frequency modulation continuous wave signal is linear frequency modulation sawtooth continuous wave signal.
Accordingly, present invention also offers a kind of signal processing apparatus based on continuous wave weather radar system, described device comprises:
A/D converting unit, for analogue echoes signal and echo signal of intermediate frequency are carried out A/D conversion, obtains echo digital signal;
Phase-shift detection unit, for described echo digital signal is carried out phase-shift detection, obtains I/Q data;
Deramp processing unit, for described I/Q data are carried out digital deramp processing, then obtains difference frequency echo data by distance matched filter;
Windowing process unit, for carrying out windowing process to described difference frequency echo data;
First dimension fft processing unit, ties up FFT process for entering execution first to the difference frequency echo data through windowing process, obtains the range distribution characteristic of echo and the echo range distribution characteristic apart from upper intensity PHASE DISTRIBUTION;
Second dimension fft processing unit, for carrying out the process of execution Two-dimensional FFT to described echo apart from upper intensity PHASE DISTRIBUTION, obtains the echo linear power spectral density distribution of each range bin;
Spectrum average treatment frequency spectrum accumulative element, for carrying out spectrum average treatment to the echo linear power spectral density distribution of described each range bin;
Filter processing unit, for carrying out land clutter filtering process to the distribution of echo linear power spectral density;
Parameter estimation unit, for carrying out parameter estimation to the echo linear power spectral density distribution after spectrum average treatment and filtering process, obtains the intensity of each range bin, speed and spectrum width data.
Preferably, in some preferred embodiment of echo signal processing equipment of the present invention, described windowing process unit comprises:
Select performance element, for selecting one or both window functions to carry out windowing process judging unit to described difference frequency echo data from window function unit according to the instruction of user, for judging the situation of meteorological intensity height change;
Window function unit, comprises the window function of some different secondary lobe degree of suppression.
Preferably, in some preferred embodiment of echo signal processing equipment of the present invention, described spectrum average treatment adopts incoherent frequency spectrum to accumulate.
Preferably, in some preferred embodiment of echo signal processing equipment of the present invention, described filter processing unit adopts the mode of plug-in type filtering.
Preferably, in some preferred embodiment of echo signal processing equipment of the present invention, described spectrum average treatment and parameter estimation unit comprise:
Unit is searched at spectrum peak, for adopting sliding window method to carry out the search of spectrum peak to the echo linear power spectral density distribution of each range bin;
Square parameter calculation unit, for carrying out the calculating of square parameter to both sides expansion centered by the spectrum peak position searched.
Preferably, in some preferred embodiment of echo signal processing equipment of the present invention, described echo signal processing equipment also comprises:
Average treatment unit, adopts utilize maximum set method for the intensity to each range bin, speed, spectrum width, carry out linear averaging, reduce data variance to data in set;
Echo power amending unit, for carrying out echo power correction according to distance matched filter amplitude versus frequency characte and intensity calibration result.
Preferably, in some preferred embodiment of echo signal processing equipment of the present invention, described linear frequency modulation continuous wave signal is linear frequency modulation sawtooth continuous wave signal.
The present invention launches continuous wave signal by emitting antenna module; 400, the reception extension set of Received signal strength adopts the synchronous method triggered to sample, and postpone very first time interval, very first time interval is corresponding with range;
Received signal strength sampling door pocket width was second time interval, and second time interval is corresponding with effective modulating bandwidth.
Described very first time interval corresponding corresponding range is set, described second time interval corresponding effective modulating bandwidth is set.Such as, when range is 15km, very first time interval can be 100us, and when effective modulating bandwidth is 5MHz, second time interval can be 500us.
Preferably, radar system of the present invention can be provided with routine, increase journey and high-resolution Three models, and normal mode can detect the weather data that range is 15km, and range resolution is 30m; Increase journey pattern and can detect the weather data that range is 24km, range resolution is 30m; High resolution mode can detect the weather data that range is 12km, and range resolution is 15m.The system sequence that the pattern configurations that radar system of the present invention is different is corresponding, can be arranged at terminal demonstration interface one key.
The preferred embodiment of control method of the present invention please refer to Fig. 5, for normal mode of operation, detection range is 15km, range resolution is 30m, transmits and adopts slope to be 0.01MHz/us, and the repetition period is the linear frequency modulation continuous wave signal of 600us, Received signal strength adopts and synchronous triggers that to be used for the sampling of synchronous Received signal strength initial, postpone the range of the corresponding 15km of 100us, Received signal strength sampling door pocket width is 500us, to ensure effective modulating bandwidth of 5MHz.
Preferably, in some preferred embodiment of control method of the present invention, described linear frequency modulation continuous wave signal is linear frequency modulation sawtooth continuous wave signal.
The weather radar system of linear frequency modulation continuous wave system, in the design of waveform, can adopt triangular wave or sawtooth wave.For point target, two kinds of waveforms can obtain the Distance geometry radial velocity of target by corresponding algorithm, but owing to being align by moving target the different difference frequencies that negative slope produces to carry out computing and obtain doppler velocity, therefore there is target marriage problem in triangular wave.Meteorological target belongs to body target, and the particle in target is difficult to carry out pairing process, and therefore as meteorological target detection, Waveform Design can only select sawtooth fashion.
Adopt the weather radar system of above-mentioned control method, because transmitting and receiving work simultaneously, there is no detection blind area in theory.
It should be noted that, in actual use, the signal processor of the preferred embodiment of weather radar system of the present invention can design based on general and special VLSI (very large scale integrated circuit), adopt the FPGA of high integrated, high precision, high-level efficiency, highly reliable and low-power consumption, for the singularity of continuous wave system, take advanced algorithm and up-to-date DSP technology, complete the calculation process of echo.Signal processor carries out the transmission of instruction and data by gigabit networking and monitoring module, terminal display system.
The present invention is mainly used in meteorological field, be mainly used in the Precipitation Clouds of measurement 15 ~ 30m highl stratification and the linear power spectral density information of precipitation echo, can Precipitation Clouds below real-time detection 0.2 ~ 24km height or precipitation in the intensity of each height layer, vertical speed and spectrum width information.Also can be applied in the fields such as civil aviaton, agricultural, water conservancy and atmospheric physics research simultaneously.
Claims (10)
1., based on an echo signal processing method for continuous wave system weather radar system, transmitting of described weather radar system adopts linear frequency modulation continuous wave signal, and it is characterized in that, described echo signal processing method comprises the following steps:
Analogue echoes signal is carried out A/D conversion, obtains echo digital signal;
Described echo digital signal is carried out phase-shift detection, obtains I/Q data;
Described I/Q data are carried out digital deramp processing, then obtains difference frequency echo data by distance matched filter;
Windowing process is carried out to described difference frequency echo data;
First dimension FFT process is carried out to the difference frequency echo data through windowing process, obtains the range distribution characteristic of echo and echo apart from upper intensity PHASE DISTRIBUTION;
Apart from upper intensity PHASE DISTRIBUTION, Two-dimensional FFT process is carried out to described echo, obtains the echo linear power spectral density distribution of each range bin;
Spectrum average treatment is carried out to the echo linear power spectral density distribution of described each range bin;
Land clutter filtering process is carried out to the echo linear power spectral density distribution of each range bin after spectrum average treatment;
Parameter estimation is carried out to the echo linear power spectral density distribution of each range bin successively after spectrum average treatment and filtering process, obtains the intensity of each range bin, speed and spectrum width data.
2. echo signal processing method according to claim 1, is characterized in that, described windowing process step performs one or both window functions that user selects in advance from the window function of the some different secondary lobe degree of suppression preset.
3. echo signal processing method according to claim 1 and 2, is characterized in that, described spectrum average treatment adopts incoherent frequency spectrum to accumulate;
Described land clutter filtering process adopts plug-in type filtering processing mode;
Described parameter estimation comprises the following steps:
Adopt sliding window method to carry out the search of spectrum peak to the echo linear power spectral density distribution of each range bin, centered by the spectrum peak position searched, carry out the calculating of square parameter to both sides expansion setting range.
4. echo signal processing method according to claim 1 and 2, is characterized in that, described echo signal processing method is further comprising the steps of:
To intensity, speed, the spectrum width data acquisition maximum set method of each range bin, linear averaging is carried out to the data in set, reduce data variance;
Echo power correction is carried out according to distance matched filter amplitude versus frequency characte and intensity calibration result.
5. echo signal processing method according to claim 1 and 2, is characterized in that: described linear frequency modulation continuous wave signal is linear frequency modulation sawtooth continuous wave signal.
6., based on an echo signal processing equipment for continuous wave system weather radar system, transmitting of described weather radar system adopts linear frequency modulation continuous wave signal, and it is characterized in that, described device comprises:
A/D converting unit, for analogue echoes signal is carried out A/D conversion, obtains echo digital signal;
Phase-shift detection unit, for described echo digital signal is carried out phase-shift detection, obtains I/Q data;
Deramp processing unit, for described I/Q data are carried out digital deramp processing, then obtains difference frequency echo data by distance matched filter;
Windowing process unit, for carrying out windowing process to described difference frequency echo data;
First dimension fft processing unit, for carrying out the first dimension FFT process to the difference frequency echo data through windowing process, obtains echo apart from upper intensity PHASE DISTRIBUTION;
Second dimension fft processing unit, for carrying out Two-dimensional FFT process to described echo apart from upper intensity PHASE DISTRIBUTION, obtains the distribution of echo linear power spectral density;
Spectrum average treatment unit, for carrying out spectrum average treatment to the echo linear power spectral density distribution of described each range bin;
Filter processing unit, for carrying out land clutter filtering process to the distribution of echo linear power spectral density;
Parameter estimation unit, for carrying out parameter estimation to the echo linear power spectral density distribution after spectrum average treatment and filtering process, obtains the intensity of each range bin, speed and spectrum width data.
7. echo signal processing equipment according to claim 6, is characterized in that, described windowing process unit comprises:
Select performance element, for selecting one or both window functions to carry out windowing process to described difference frequency echo data from window function unit according to the instruction of user;
Window function unit, comprises the window function of some different secondary lobe degree of suppression.
8. the echo signal processing equipment according to claim 6 or 7, is characterized in that,
Described spectrum average treatment adopts incoherent frequency spectrum to accumulate;
Described land clutter filtering process adopts the mode of plug-in type filtering;
Described parameter estimation unit comprises:
Unit is searched at spectrum peak, for adopting sliding window method to carry out the search of spectrum peak to the echo linear power spectral density distribution of each range bin;
Square parameter calculation unit, for carrying out the calculating of square parameter to both sides expansion centered by the spectrum peak position searched.
9. the echo signal processing equipment according to claim 6 or 7, is characterized in that, described echo signal processing equipment also comprises:
Average treatment unit, adopts maximum set method for the intensity to each range bin, speed, spectrum width, carries out linear averaging, reduce data variance to data in set;
Echo power amending unit, for carrying out echo power correction according to distance matched filter amplitude versus frequency characte and intensity calibration result.
10. the echo signal processing equipment according to claim 6 or 7, is characterized in that: described linear frequency modulation continuous wave signal is linear frequency modulation sawtooth continuous wave signal.
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