CN112684421A - Coherent calibration source system for linear frequency modulation continuous wave radar - Google Patents
Coherent calibration source system for linear frequency modulation continuous wave radar Download PDFInfo
- Publication number
- CN112684421A CN112684421A CN201910987447.5A CN201910987447A CN112684421A CN 112684421 A CN112684421 A CN 112684421A CN 201910987447 A CN201910987447 A CN 201910987447A CN 112684421 A CN112684421 A CN 112684421A
- Authority
- CN
- China
- Prior art keywords
- radar
- signal
- frequency
- calibration source
- lfm
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 230000001427 coherent effect Effects 0.000 title claims abstract description 26
- 238000006243 chemical reaction Methods 0.000 claims abstract description 75
- 238000012545 processing Methods 0.000 claims abstract description 37
- 238000001914 filtration Methods 0.000 claims abstract description 16
- 230000003321 amplification Effects 0.000 claims abstract description 14
- 238000003199 nucleic acid amplification method Methods 0.000 claims abstract description 14
- 238000001228 spectrum Methods 0.000 claims abstract description 13
- 238000013139 quantization Methods 0.000 claims abstract description 5
- 238000012360 testing method Methods 0.000 claims description 42
- 238000001514 detection method Methods 0.000 claims description 20
- 230000005540 biological transmission Effects 0.000 claims description 15
- 238000004088 simulation Methods 0.000 claims description 9
- 230000005855 radiation Effects 0.000 claims description 8
- 230000035945 sensitivity Effects 0.000 claims description 8
- 230000010355 oscillation Effects 0.000 claims description 6
- 238000005070 sampling Methods 0.000 claims description 6
- 230000005284 excitation Effects 0.000 claims description 5
- 238000004364 calculation method Methods 0.000 claims description 3
- 230000003111 delayed effect Effects 0.000 claims description 3
- 230000001934 delay Effects 0.000 claims description 2
- 238000000034 method Methods 0.000 description 49
- 230000006870 function Effects 0.000 description 11
- 238000005516 engineering process Methods 0.000 description 9
- 230000006872 improvement Effects 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 230000008901 benefit Effects 0.000 description 5
- 230000015572 biosynthetic process Effects 0.000 description 5
- 238000007689 inspection Methods 0.000 description 5
- 238000003786 synthesis reaction Methods 0.000 description 5
- 230000010354 integration Effects 0.000 description 4
- 238000011056 performance test Methods 0.000 description 4
- 230000008859 change Effects 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000010586 diagram Methods 0.000 description 3
- 238000001308 synthesis method Methods 0.000 description 3
- 238000004458 analytical method Methods 0.000 description 2
- 230000006835 compression Effects 0.000 description 2
- 238000007906 compression Methods 0.000 description 2
- 238000013461 design Methods 0.000 description 2
- 230000033001 locomotion Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 230000003068 static effect Effects 0.000 description 2
- 238000010897 surface acoustic wave method Methods 0.000 description 2
- 238000009825 accumulation Methods 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000002457 bidirectional effect Effects 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000018109 developmental process Effects 0.000 description 1
- 238000003745 diagnosis Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000001307 helium Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- SWQJXJOGLNCZEY-UHFFFAOYSA-N helium atom Chemical compound [He] SWQJXJOGLNCZEY-UHFFFAOYSA-N 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 125000004435 hydrogen atom Chemical class [H]* 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 239000013307 optical fiber Substances 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000004576 sand Substances 0.000 description 1
- 230000003595 spectral effect Effects 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 238000011282 treatment Methods 0.000 description 1
Images
Abstract
The invention discloses a coherent calibration source system of a linear frequency modulation continuous wave radar, aiming at providing a coherent calibration source system with high reliability and flexibility, which is realized by the following technical scheme: the receiving antenna collects the transmitting signal of the linear frequency modulation continuous wave radar needing calibration, sends the signal to the down-conversion unit, carries out frequency conversion on the radar transmitting signal and the local oscillator signal generated by the reference source, filters the signal and sends the signal to the baseband processing unit to carry out analog-to-digital (A/D) conversion, completes the quantization, delay playback and related control of the receiving channel signal, completes distance delay and Doppler frequency superposition according to the requirement, reforms the analog signal through digital-to-analog (D/A) conversion, sends the signal to the up-conversion unit, carries out frequency conversion, filtering and amplification on the baseband signal generated by the baseband processing unit and the local oscillator signal generated by the reference source, completes the frequency spectrum moving, sends the signal to the transmitting antenna, converts the radio frequency signal into an electromagnetic wave signal to radiate the radar, and externally radiates the.
Description
Technical Field
The invention relates to a calibration source system of a phase-coherent system of a linear frequency modulation continuous wave (LFM-CW) radar.
Background
Linear frequency modulated continuous wave (LFM-CW) radar is a technique for obtaining range information in a radar by frequency modulating a continuous wave signal. The frequency modulation used in radar is various, and the waveforms of the transmitted signals of radars with different systems, radars with different purposes and radars with different performance requirements are different. The LFM-CW radar adopts a continuous wave system, determines the distance to a target by changing the frequency of a transmitted signal in time and measuring the frequency difference of an echo signal relative to the transmitted signal, and can also measure the radial velocity of the target by using the doppler effect. Compared with other system radars, the linear frequency modulation continuous wave radar has good maneuverability and can adapt to complex and severe environments; the receiver has high sensitivity; the required emission peak power is lower, the modulation is easy, the circuit is simple, the size is small, the weight is light, the cost is low, the signal processing is simple, and the like. With the increasing importance of radar function, the function and performance of radar are improved, so that the complexity of a radar system is increased, and the test difficulty of the radar is increased. The development and the perfection of the radar test technology generate massive radar test data, and a method for storing, accurately analyzing and efficiently managing the data in real time provides huge challenges and provides higher requirements for accurate and comprehensive system function and performance tests of each stage in the whole life cycle of the radar.
The test of the linear frequency modulation continuous wave calibration source system of the coherent system is divided into built-in test and off-line test. The built-in test is to utilize the technology of the built-in self-test of the radar, provide the BIT information by the radar itself, mainly used for checking, testing and recording the performance of the radar system when the radar works, and monitor the fault condition of each stage when the radar runs, so that a user can really master the working condition of the radar system. The off-line test is to test the radar by using an Automatic Test System (ATS) and perform fault reasoning on the test result. The testing capability of the BIT requires that the BIT device has the capability of sending excitation, response recovery and intelligent analysis, which requires a large amount of software and hardware to be added to the whole system and each subsystem or even individual components, which means the reduction of the reliability of the system, makes the system more complex and more difficult to use and maintain, and the BIT is established to realize the testing capability on the premise that the BIT device has no fault, and once the BIT device has the fault, a false alarm, and incapability of detection and diagnosis are caused. And an external ATS test is required for the fault points which cannot be detected by BIT.
The content and the range of the radar test of the linear frequency modulation continuous wave calibration source system of the prior coherent system have universality. The test can be carried out at different levels from a component/chip level, a circuit board level to a functional unit level, a subsystem level, a system level and the like; the method can test different aspects such as radar emission signal parameters, radar receiver performance parameters, radar system performance and the like; the performance indexes required by a special radar system, such as the sensitivity of a radar receiver, the angular tracking characteristic, the Doppler frequency coverage range of the receiver, the measurement accuracy of the measurement radar on a high-speed target and other technical parameters can be tested. There are two main methods of radar testing: firstly, a large number of universal instruments and meters are used to be matched with a special test tool to test partial parameters (mainly static parameters) of the radar; and secondly, dynamically detecting the flying, namely releasing the balloon, and carrying out radar cross-sectional area (RCS) calibration and remote control of the drone by hanging the metal standard ball by the unmanned aerial vehicle to test the actual detection performance of the radar. In the past, a radar calibration source is generally an optical fiber delay type fixed single-target calibration signal source, RCS measurement adopts a balloon or kite hanging and placing mode, but the calibration success rate is not high due to the influence of weather.
The method 1 focuses on the test of the static performance of a system in a single device and a device, and cannot comprehensively reflect the overall dynamic performance of the system. Instruments and meters used for testing are various, precise and expensive, cannot be deployed in all units simultaneously according to the number of the radars, and are inconvenient to detect the radars at any time, so that the testing method is greatly limited. In addition, the method needs to rely on instruments to generate numerous and complicated input excitation signals, a very large scale integrated circuit is mostly adopted in the radar digital plug-in, FPGA input pins are mostly bidirectional, most signals are only interconnected in a printed board, the excitation signals provided by the instruments cannot meet the requirement in quantity, and the complexity cannot meet the testing requirement. Due to various reasons, the actual measurement indexes of part of subsystems can not meet the design index requirements or the performance of part of subsystems is reduced due to aging, the situation can bring great influence on the actual test work, whether the influence is within an acceptable range or not can not give a quick and intuitive conclusion. Often, the analysis and judgment are carried out by depending on the actual experience of technicians and simple theoretical calculation, and an objective and scientific means is lacked to make accurate definition and actual inspection.
Although the 2 nd method can test the key performance of the radar, such as detection power, detection precision and the like, the dynamic flight detection and the actual work have larger difference, the performance of the equipment is not comprehensively detected, and the states of different types of targets detected by the radar cannot be simulated. In addition, dynamic flight inspection is limited by manpower, material resources, airspace and the like, so that the cost is high, a large number of flight inspection shelves are often needed for obtaining accurate data, and the flight inspection cannot be frequently performed in actual operation or organized at any time according to needs.
One of the major problems in measuring the characteristics of an outfield radar target is how to calibrate with high accuracy, i.e. to establish a strict mathematical relationship between RCS and the power or voltage measured by the radar. The common calibration method is divided into a relative calibration method and an absolute calibration method, the relative calibration method calculates the RCS value of a target by the power (or voltage) ratio measured by a standard target which is known and isotropic to the RCS and a target to be measured, and the RCS value of a calibration body is accurately measured. The absolute calibration method is to directly calibrate the measured radar parameters and then calculate the RCS value of the target according to a radar equation. In actual use, the relative calibration method is represented by a calibration ball calibration method, and the absolute calibration method is represented by a signal source calibration method. Both methods have advantages and disadvantages. The calibration method of the calibration ball only needs to prepare a hydrogen (helium) ball and release the calibration ball into the air by using a winch, the equipment is simple and easy to operate, but the calibration method of the calibration ball is greatly restricted by meteorological conditions. And the signal source calibration method is adopted, so that the equipment is relatively complex and the technical requirement is high. Compared with a calibration ball calibration method, the error caused by the alignment precision of the radar antenna and the signal source antenna in the signal source calibration method is small. The target characteristic measuring radar is mostly under broadband and multi-polarization conditions, and can greatly influence the accuracy of RCS measuring results.
At present, means for external field debugging and testing of Linear Frequency Modulation (LFM) continuous wave- (CW) -High Frequency (HF) radar is lacked. The prior art discloses a radar performance test system of a quasi-coherent system, which is a full digital simulation system based on a digital quadrature modulation technology (DQM) and a direct digital frequency synthesis (DDS) technology, and mainly completes the performance test of an LFM-CW-HF radar by simulating a target signal and an interference signal of the LFM-CW-HF radar, but the LFM-CW-HF radar of the quasi-coherent system adopts the digital quadrature modulation technology and the direct digital frequency synthesis technology to occupy a large amount of instrument resources.
At present, there are two basic methods of generating chirp signals, an analog method and a digital method. The conventional simulation methods are further classified into an active method and a passive method. The active method is to generate a chirp signal using a linear sawtooth Voltage Controlled Oscillator (VCO), which is also called a direct synthesis method. To achieve good linearity using this method, VC0 and the sawtooth waveform generator must be optimally designed. The direct synthesis method simulates and generates a chirp signal, and although the method is a simpler method for generating an FMCW signal, the method has the outstanding problems that the phases of a carrier wave of the generated chirp signal and a reference signal are not coherent, the coherence, the long stability and the short stability of the signal cannot be ensured to be not ideal, the frequency can generate drift along with the change of temperature, the phase noise index is not high, and the like. These disadvantages determine that the chirped continuous wave signal generated by the direct VCO method is strictly coherent during the period of the required signal, and the use of the LFMCW radar is limited, which ensures low phase noise and high frequency stability, and for the oscillator, the long-term stability and the short-term stability are poor, and the oscillation frequency generated when the temperature changes may drift, and the phase noise performance is also poor. A common way of passive method is to use a Surface Acoustic Wave (SAW) device to perform spectral broadening and compression of waveform signals. The method is mainly used in pulse system radars to realize compression processing of the pulse frequency modulation signals. The frequency-modulated continuous wave signal is generated in the mode, and an all-pass or band-pass network with a linear group delay characteristic is mainly designed. The linear frequency modulation signal generated by the method is limited by the level of the device, the performance of the large time-bandwidth product cannot be realized, and the application range of the linear frequency modulation signal is limited. It is seen that it is difficult to achieve the desired performance level of the signal using simulation. The digital method is a new developed method, and is divided into two methods, namely a waveform storage direct reading method and a direct digital synthesis frequency (DDS) method. The waveform storage direct reading method is a method of storing sampling values of an LFM signal in a memory under specific sampling frequency f, a signal E and a signal time width Z, and directly generating an analog signal after performing digital-to-analog conversion and low-pass filtering on a read waveform under a clock; direct digital frequency synthesis is a method of generating an analog signal by phase accumulation, amplitude look-up table, and digital-to-analog conversion. The waveform storage direct reading method has the advantages of simple principle and low cost, but has the defect of relatively complex structure; the direct digital frequency synthesis method has the advantages of high integration level, good flexibility, simple circuit structure and the like, but has the disadvantages of higher cost, weaker amplitude and phase compensation capability and the like. Compared with the traditional frequency synthesis technology, the DDS technology has higher frequency resolution, continuous phase change and higher frequency switching rate than the common method, and can modulate an output signal, thereby meeting the requirements of modern radar signals. This method is also currently used to generate some radar signals. It mainly utilizes one or more different reference frequency sources to produce output signals of several discrete frequencies by means of harmonic generator, and directly produces output signals of several discrete frequencies by means of frequency multiplication, frequency division, frequency mixing, filtering and analog switch; the signal obtained by the method has the advantages of higher frequency stability, lower phase noise and higher frequency conversion speed; meanwhile, the device also has a plurality of inevitable defects, such as more complex structure and higher debugging difficulty compared with the similar signal generator, and also has poor stray rejection performance.
Disclosure of Invention
The invention aims to provide a coherent calibration source system of a linear frequency modulation continuous wave radar, which has high reliability, high integration level and flexibility and can finish the functions of radar distance calibration, radar emission signal power detection, radar sensitivity test, improvement factor test, channel detection, track processing detection and the like aiming at the defects of the existing linear frequency modulation continuous wave radar testing technology.
The above functions of the present invention can be achieved by the following measures, and a system for calibrating a coherent standard of a chirped continuous wave radar includes: the device comprises an up-conversion unit connected with a transmitting antenna, a down-conversion unit connected with a receiving antenna, a reference source connected between the up-conversion unit and the down-conversion unit, and a baseband processing unit connected with the reference source and a power supply, and is characterized in that the receiving antenna collects transmitting signals of a linear frequency modulation continuous wave radar to be calibrated and sends the signals to the down-conversion unit, the down-conversion unit carries out frequency conversion and filtering on the radar transmitting signals collected by the receiving antenna and local oscillator signals generated by the reference source to complete low noise amplification, frequency spectrum shifting and frequency band signals of the radar transmitting signals, the signals are sent to the baseband processing unit for processing, the baseband processing unit carries out sampling, filtering and analog-to-digital (A/D) conversion on analog signals sent by the down-conversion unit, and quantization, digital down-conversion (DDC), digital up-conversion (DUC) and digital down-conversion (DUC) of receiving channel signals, The device comprises a base band processing unit, an up-conversion unit, a transmitting antenna, a storage unit, a delay playback unit, a delay control unit, a frequency spectrum shifting unit and a frequency spectrum shifting unit, wherein the base band processing unit is used for generating a base band signal, the up-conversion unit is used for carrying out frequency conversion, filtering and amplification on the base band signal and a local oscillation signal generated by a reference source, the base band signal is transmitted to the up-conversion unit, the frequency spectrum shifting unit is used for carrying out frequency conversion, filtering and amplification on the base band signal and the local oscillation signal, the base band signal is transmitted to the transmitting antenna, the transmitting antenna is used for receiving a radio.
Compared with the prior art, the invention has the following beneficial effects:
the reliability is high, and the integrated level is high. The invention adopts the up-conversion unit connected with the transmitting antenna, the down-conversion unit connected with the receiving antenna, the reference source connected between the up-conversion unit and the down-conversion unit, the baseband processing unit connected with the reference source and the power supply, and the linear frequency modulation continuous wave radar coherent calibration source system formed by integration level, has strong function and high cost performance, can effectively control the distance and speed range to be tested, has the advantage of high integration level compared with the traditional test by utilizing a universal instrument, and can achieve the reliability of effective test on target detection.
Flexibility is provided. The invention adopts the down-conversion unit to carry out frequency conversion and filtering on the radar transmitting signal collected by the receiving antenna and the local oscillator signal generated by the reference source, completes low-noise amplification, frequency spectrum shifting and frequency band signal of the radar transmitting signal, and sends the signal to the baseband processing unit for processing, and the working system is advanced. By utilizing the delay transponder with coherence and high cost performance, an arbitrary waveform generator of the delay transponder can automatically generate various signals when no received signal exists, the polarization of a receiving and transmitting antenna is orthogonal, the requirements on vertical and horizontal polarization calibration can be met simultaneously, the receiving and transmitting delay can be continuously adjusted, the receiving and transmitting delay can be kept unchanged after adjustment, the gain can be kept constant along with the change of factors such as time, temperature and humidity, the received signal is subjected to treatments such as undistorted delay and amplification, and the calibration requirements on various pulse waveforms transmitted by a target characteristic measurement radar can be met. High flexibility and repeated use. The problems that the traditional calibration source is low in reliability, heavy in size, poor in frequency stability, easy to interfere, poor in applicability, high in use environment requirement, incomplete in test coverage and the like are solved.
The system has complete functions. The invention baseband processing unit samples, filters and A/D converts the analog signal sent by the down-conversion unit, according to the baseband processed clock signal provided by the reference source, completes the quantization of the received channel signal, digital down-conversion DDC, digital up-conversion (DUC), storage, delay playback and related control, completes the distance delay and superposition of Doppler frequency according to the requirement, and reforms the analog signal through D/A conversion, and sends to the up-conversion unit, the up-conversion unit carries out frequency conversion, filtering and amplification on the baseband signal generated by the baseband processing unit and the local oscillator signal generated by the reference source, completes the spectrum shift, and sends to the transmitting antenna, thus completing the test of radar main functions such as radar distance calibration, radar transmitting signal power detection, radar sensitivity test, improvement factor test, channel detection and track processing detection, the system function and performance test can be carried out on the radar system comprehensively. The received radar signal is in the linear region of the signal source amplifier, the signal radiated after the amplification is in the linear region of the RCS measurement radar receiver, and the like, and the working requirements of RCS radar on various broadband signals can be met.
Drawings
FIG. 1 is a schematic block diagram of a coherent calibration source system for a chirped continuous wave radar in accordance with the present invention.
FIG. 2 is a schematic diagram of a calibration source application of the present invention.
Fig. 3 is a schematic diagram of the variation of the chirp of the source transmit signal and the frequency of the received signal scattered back according to the present invention.
Detailed Description
See fig. 1. In a preferred embodiment described below, a system for a chirped continuous wave radar coherent calibration source for a chirped continuous wave-like calibration source of a coherent system comprises: the calibration system comprises an up-conversion unit connected with a transmitting antenna, a down-conversion unit connected with a receiving antenna, a reference source connected between the up-conversion unit and the down-conversion unit, and a baseband processing unit connected with the reference source and a power supply, wherein the power supply mainly provides stable and reliable power supply for the whole calibration system and has the functions of input protection, output power supply overvoltage, undervoltage, overcurrent protection and the like. The reference source mainly generates a clock signal required by the baseband processing unit and local oscillator signals required by the up-conversion unit and the down-conversion unit. The receiving antenna collects the transmitted signal of the linear frequency modulation continuous wave radar to be calibrated, the signal is sent to the down-conversion unit, the down-conversion unit carries out frequency conversion and filtering on the radar transmitted signal collected by the receiving antenna and a local oscillation signal generated by a reference source, low noise amplification, frequency spectrum shift and frequency band signal of the radar transmitted signal are completed, the signal is sent to the baseband processing unit for processing, the baseband processing unit carries out sampling, filtering and analog-digital A/D conversion on the analog signal sent by the down-conversion unit, quantization, digital down-conversion DDC, digital up-conversion (DUC), storage, delayed playback and related control of a receiving channel signal are completed according to a clock signal of baseband processing provided by the reference source, and after distance delay and Doppler frequency superposition are completed according to needs, the analog signal is reformed through digital-analog D/A conversion and sent to the up-conversion unit, the up-conversion unit carries out frequency conversion, filtering and amplification on a baseband signal generated by the baseband processing unit and a local oscillator signal generated by a reference source, then completes spectrum movement, and sends the signals to the transmitting antenna, the transmitting antenna receives the radio-frequency signal output by the up-conversion unit, converts the radio-frequency signal into an electromagnetic wave signal to radiate to a radar, and externally radiates a signal generated by a calibration source.
The linear frequency modulation continuous wave radar starting-up radiation signal is received by the calibration source system through the receiving antenna to obtain a radar excitation signal, and the coherent system of the calibration source system is realized through the modes of storage, delayed forwarding and radar re-receiving.
See fig. 2. During application, the calibration source is placed on a flat ground with a distance R from the linear frequency modulation continuous wave radar, and the erection height is basically consistent with the height of the radar. The linear frequency modulation continuous wave radar transmitting antenna transmits radar radiation signals to the calibration source receiving antenna, and the calibration source transmitting antenna transmits the calibration source radiation signals to the linear frequency modulation continuous wave radar receiving antenna.
Each function of the present invention will be specifically described below.
See fig. 3. LFM-CW radar at an initial frequency f0And (3) for a coordinate origin, changing the frequency of a transmitting signal on time t during transmission, calibrating the distance of the linear frequency modulation continuous wave radar, and measuring the distance of a target by constructing a rectangular coordinate system in the frequency f range of a receiving signal relative to the transmitting signal. Frequency difference f between peaks on two curves of the received signal with respect to the frequency of the transmitted signaldA Doppler shift in which a moving object is superimposed on the scattered signal, an
In the formula, λ is radar wavelength, and v is moving speed of the moving target.
The frequency f of the transmitting signal and the receiving signal of the LFM-CW radar is within one modulation period TmOf frequency modulation of0+△f-f0Range of- Δ f, two phases formed by intersecting axes of lower and upper edges of the peak of the frequencySimilar to a triangle, when two relation curves of the frequency f of the transmitting signal and the frequency f of the receiving signal relative to the time tau are both positive slopes, according to the frequency difference fb of the transmitting signal and the receiving signal, and through the geometric relation similar to the triangle, the instantaneous frequency difference between the two relation curves of the frequency f of the transmitting signal and the frequency f of the receiving signal relative to the time t is obtained through linear triangular modulation
When the two curves of the received signal relative to the frequency f of the transmitted signal are both negative slopes, the instantaneous frequency difference between the two curves can be obtained by linear triangular modulation according to the geometric relation of similar triangle
And is
Where Δ f is the frequency modulation range, R is the distance between the calibration source and the LFM-CW radar, and c is the transmission speed of electromagnetic waves in space, about 3 × 108m/s，TmIs the modulation period.
Calibrating the distance between the source and the LFM-CW radar
In the formula (I), the compound is shown in the specification,
is the average frequency difference.
When the calibration source calibrates the distance of the LFM-CW radar, firstly, the working frequency f of the LFM-CW radar is set1The re-emission of the calibration source has a certain frequency difference f relative to the working frequency of the LFM-CW radarbSignal f of1+fbThe LFM-CW radar receives the signal and performs a distance calculation on the signal to obtain a distance R1For calibrating the distance R and frequency difference f between the source and the LFM-CW radarbCorresponding distance R2Sum according to
Theoretically calculating a certain frequency difference fbThe corresponding distance is R2If the distance R between the calibration source and the LFM-CW radar is equal to R1-R2Therefore, the calibration of the LFM-CW to the radar distance is realized.
For the LFM continuous wave radar system, the gain G of the transmitting antenna of the known LFM-CW radar system is R, LFM-CW radar system with the calibration source distancetCalibration source receiving antenna gain GrIn the case of (2), the one-way transmission equation of the LFM-CW radar radiation signal relative to the calibration source received signal is: transmission power
LFM-CW radar transmission signal power detection transmission power
The signal power of the receiving antenna port is obtained through the calibration source, the radar radiation power detection can be completed, and the wavelength lambda (2cm) can be regarded as a constant.
In the radar sensitivity test, a calibration source delays signals to the outside of a radar blind area, then radiates the signals to a radar system through a transmitting antenna, and transmits power P according to radartEquation, calibration source simulation target echo power Prσ：
Wherein G ist、GrAnd the gain is the antenna gain of the LFM-CW radar, and R is the distance between the LFM-CW radar and a calibration source. According to known theory, calibration source simulation target equivalent radar cross section RCS and calibration source link net gain GσThe relationship of (1) is:
sensitivity to the system is PrminThe simulated target distance of the LFM-CW radar of (1) is RsThe time-simulated target equivalent RCS should be:
therefore, in the known LFM-CW radar transmission power GtIn the case of (3), the simulation target distance R is specifiedsAnd adjusting the link gain of the calibration system, counting the detection probability of the LFM-CW radar system, and measuring the sensitivity of the LFM-CW radar system.
And (5) testing an improvement factor. And adjusting the Doppler characteristic of the calibration source system simulation target, and counting the detection results of the LFM-CW radar system under different multi-general characteristics to obtain the improvement factor of the radar.
Channel detection and track processing. Setting a calibration source to output a simulated target signal containing Doppler characteristics, radiating the signal to an LFM-CW radar system through a transmitting antenna, and carrying out amplification, frequency conversion and SFC control processing on the signal by the LFM-CW radar receiving subsystem; the signal processing subsystem carries out digital sampling and resolving on the difference frequency IQ analog signal sent by the receiving subsystem; and the data processing and communication control subsystem completes data processing according to the target signals resolved by the signal processing subsystem and establishes a track of target motion, so that the channel detection and track processing inspection of the radar system are realized.
The foregoing is directed to the preferred embodiment of the present invention and it is noted that the above-mentioned embodiments illustrate rather than limit the invention, and that those skilled in the art will be able to design alternative embodiments without departing from the scope of the appended claims. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.
Claims (10)
1. A coherent calibration source system for a linear frequency modulation continuous wave radar comprises: the device comprises an up-conversion unit connected with a transmitting antenna, a down-conversion unit connected with a receiving antenna, a reference source connected between the up-conversion unit and the down-conversion unit, and a baseband processing unit connected with the reference source and a power supply, and is characterized in that the receiving antenna collects transmitting signals of a linear frequency modulation continuous wave radar to be calibrated and sends the signals to the down-conversion unit, the down-conversion unit carries out frequency conversion and filtering on the radar transmitting signals collected by the receiving antenna and local oscillator signals generated by the reference source to complete low noise amplification, frequency spectrum shifting and frequency band signals of the radar transmitting signals, the signals are sent to the baseband processing unit for processing, the baseband processing unit carries out sampling, filtering and analog-to-digital (A/D) conversion on analog signals sent by the down-conversion unit, and quantization, digital down-conversion (DDC), digital up-conversion (DUC) and digital down-conversion (DUC) of receiving channel signals, The device comprises a base band processing unit, an up-conversion unit, a transmitting antenna, a storage unit, a delay playback unit, a delay control unit, a frequency spectrum shifting unit and a frequency spectrum shifting unit, wherein the base band processing unit is used for generating a base band signal, the up-conversion unit is used for carrying out frequency conversion, filtering and amplification on the base band signal and a local oscillation signal generated by a reference source, the base band signal is transmitted to the up-conversion unit, the frequency spectrum shifting unit is used for carrying out frequency conversion, filtering and amplification on the base band signal and the local oscillation signal, the base band signal is transmitted to the transmitting antenna, the transmitting antenna is used for receiving a radio.
2. The chirped continuous wave radar coherent calibration source system according to claim 1, wherein: the calibration source system is used for detecting and receiving radar radiation signals through the receiving antenna to obtain radar excitation signals, and a coherent system of the calibration source system is realized through storage, delayed forwarding and radar re-receiving.
3. The chirped continuous wave radar coherent calibration source system according to claim 1, wherein: LFM-CW radar at an initial frequency f0For the origin of coordinates, the frequency of a transmitted signal is changed at time t during transmission, the distance of a linear frequency modulation continuous wave radar is calibrated, and a rectangular coordinate system is constructed in the frequency f range of a measured received signal relative to the transmitted signal to measureDistance of the object, frequency difference between peaks on two curves of the received signal with respect to the frequency of the transmitted signal fdA Doppler shift in which a moving object is superimposed on the scattered signal, an
In the formula, λ is LFM-CW radar wavelength, and v is moving speed of moving target.
4. The chirped continuous wave radar coherent calibration source system according to claim 1, wherein: the frequency f of the transmitting signal and the receiving signal of the LFM-CW radar is within one modulation period TmOf frequency modulation of0+△f-f0And in the range of minus delta f, two similar delta triangles are formed by intersecting coordinate axes of the lower edge and the upper edge of the peak value of the frequency, when two relation curves of the frequency f of the transmitting signal and the frequency f of the receiving signal relative to the time tau are both positive slopes, according to the frequency difference fb of the transmitting signal and the receiving signal, and through the geometrical relation of the similar delta triangles, the instantaneous frequency difference between the two relation curves of the frequency f of the transmitting signal and the frequency f of the receiving signal relative to the time t is obtained by linear triangular modulation
In the formula, Δ f is the frequency modulation range, R is the distance between the calibration source and the LFM-CW radar, and c is the transmission speed of the electromagnetic wave in the space.
5. The chirped continuous wave radar coherent calibration source system according to claim 4, wherein: when the two curves of the received signal relative to the frequency f of the transmitted signal are both negative slopes, the instantaneous frequency difference between the two curves can be obtained by linear triangular modulation according to the geometric relation of similar triangle
And is
Where Δ f is the frequency modulation range, R is the distance between the calibration source and the LFM-CW radar, c is the transmission speed of electromagnetic wave in space, and T ismIs the modulation period.
6. The chirped continuous wave radar coherent calibration source system according to claim 5, wherein: distance between calibration source and LFM-CW radar
And the number of the first and second electrodes,
is the average frequency difference.
7. The chirped continuous wave radar coherent calibration source system according to claim 6, wherein: when the calibration source calibrates the distance of the LFM-CW radar, firstly, the working frequency f of the LFM-CW radar is set1The re-emission of the calibration source has a certain frequency difference f relative to the working frequency of the LFM-CW radarbSignal f of1+fbThe LFM-CW radar receives the signal and performs a distance calculation on the signal to obtain a distance R1For calibrating the distance R and frequency difference f between the source and the LFM-CW radarbCorresponding distance R2Sum according to
Calculating a certain frequency difference fbThe corresponding distance is R2If the distance R between the calibration source and the LFM-CW radar is equal to R1-R2Therefore, the calibration of the LFM-CW to the radar distance is realized.
8. The chirped continuous wave radar coherent calibration source system according to claim 7, wherein: transmitting antenna increase of known LFM-CW radar system and calibration source distance R, LFM-CW radar systemYi GtCalibration source receiving antenna gain GrIn the case of (2), the one-way transmission equation of the LFM-CW radar radiation signal relative to the calibration source received signal is: transmission power
LFM-CW radar transmission signal power detection transmission power
And (3) acquiring the signal power of a receiving antenna port through a calibration source, and finishing the detection of the radiation power of the radar, wherein t represents transmission, r represents reception and the wavelength lambda is a constant.
9. The chirped continuous wave radar coherent calibration source system according to claim 8, wherein: in the radar sensitivity test, a calibration source delays signals to the outside of a radar blind area, then radiates the signals to a radar system through a transmitting antenna, and transmits power P according to radartEquation, calibration source simulation target echo power Prσ：
Wherein G ist、GrAnd the gain is the antenna gain of the LFM-CW radar, and R is the distance between the LFM-CW radar and a calibration source.
10. The chirped continuous wave radar coherent calibration source system according to claim 9, wherein: according to known theory, the calibration source simulation target equivalent radar cross section RCS (sigma) and calibration source link net gain GσThe relationship of (1) is:
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910987447.5A CN112684421A (en) | 2019-10-17 | 2019-10-17 | Coherent calibration source system for linear frequency modulation continuous wave radar |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910987447.5A CN112684421A (en) | 2019-10-17 | 2019-10-17 | Coherent calibration source system for linear frequency modulation continuous wave radar |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN112684421A true CN112684421A (en) | 2021-04-20 |
Family
ID=75444479
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910987447.5A Pending CN112684421A (en) | 2019-10-17 | 2019-10-17 | Coherent calibration source system for linear frequency modulation continuous wave radar |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112684421A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113406585A (en) * | 2021-07-01 | 2021-09-17 | 四川九洲电器集团有限责任公司 | Dynamic target simulator and phased array system |
| CN116621044A (en) * | 2023-07-21 | 2023-08-22 | 常州海图信息科技股份有限公司 | Intelligent auxiliary driving system and method for monorail crane |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101082670A (en) * | 2006-06-02 | 2007-12-05 | 中国科学院电子学研究所 | Active externally coefficient potentiometer and scaling method of wideband synthetic aperture radar |
| CN102590794A (en) * | 2012-02-28 | 2012-07-18 | 北京航空航天大学 | Broadband coherent radar target simulator |
| CN103873122A (en) * | 2012-12-11 | 2014-06-18 | 中兴通讯股份有限公司 | Method, device and apparatus for sending antenna signals |
| CN104391283A (en) * | 2014-12-01 | 2015-03-04 | 无锡市雷华科技有限公司 | Radar target simulation method and system |
| CN206258575U (en) * | 2016-12-23 | 2017-06-16 | 四川先导中通光电科技有限公司 | A kind of millimeter wave transceiving module and receiver module |
| US20170343646A1 (en) * | 2014-12-16 | 2017-11-30 | Robert Bosch Gmbh | Method and device for operating a radar system of a motor vehicle |
| CN108828540A (en) * | 2018-07-25 | 2018-11-16 | 华清瑞达（天津）科技有限公司 | radar echo simulation device |
| CN109444837A (en) * | 2019-01-04 | 2019-03-08 | 北京环境特性研究所 | A kind of radar return emulation mode and device |
-
2019
- 2019-10-17 CN CN201910987447.5A patent/CN112684421A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101082670A (en) * | 2006-06-02 | 2007-12-05 | 中国科学院电子学研究所 | Active externally coefficient potentiometer and scaling method of wideband synthetic aperture radar |
| CN102590794A (en) * | 2012-02-28 | 2012-07-18 | 北京航空航天大学 | Broadband coherent radar target simulator |
| CN103873122A (en) * | 2012-12-11 | 2014-06-18 | 中兴通讯股份有限公司 | Method, device and apparatus for sending antenna signals |
| CN104391283A (en) * | 2014-12-01 | 2015-03-04 | 无锡市雷华科技有限公司 | Radar target simulation method and system |
| US20170343646A1 (en) * | 2014-12-16 | 2017-11-30 | Robert Bosch Gmbh | Method and device for operating a radar system of a motor vehicle |
| CN206258575U (en) * | 2016-12-23 | 2017-06-16 | 四川先导中通光电科技有限公司 | A kind of millimeter wave transceiving module and receiver module |
| CN108828540A (en) * | 2018-07-25 | 2018-11-16 | 华清瑞达（天津）科技有限公司 | radar echo simulation device |
| CN109444837A (en) * | 2019-01-04 | 2019-03-08 | 北京环境特性研究所 | A kind of radar return emulation mode and device |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113406585A (en) * | 2021-07-01 | 2021-09-17 | 四川九洲电器集团有限责任公司 | Dynamic target simulator and phased array system |
| CN116621044A (en) * | 2023-07-21 | 2023-08-22 | 常州海图信息科技股份有限公司 | Intelligent auxiliary driving system and method for monorail crane |
| CN116621044B (en) * | 2023-07-21 | 2023-10-20 | 常州海图信息科技股份有限公司 | Intelligent auxiliary driving system and method for monorail crane |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN106707291B (en) | Double-frequency linear frequency modulation coherent wind lidar | |
| CN107728127B (en) | Radar simulation test system | |
| CN110988830A (en) | Multi-frequency-band radar target simulator | |
| US5122805A (en) | Radio acoustic sounding system for remotely determining atmospheric temperature profiles | |
| CN104166126B (en) | A kind of simulated radar echo method for continuous wave radar | |
| JPH02140680A (en) | Method and apparatus using antenna receiving system of radio theodolite | |
| Al-Ashwal | Measurement and modelling of bistatic sea clutter | |
| CN103900616B (en) | A kind of Tacan simulator metering method and device | |
| CN113009436B (en) | Spatial angular position parameter calibration method | |
| CN110596657B (en) | Device for testing operation of distance measuring machine/Takang | |
| CN112558495B (en) | Anti-interference semi-physical simulation system and method for radar altimeter | |
| Suh et al. | Drone-based external calibration of a fully synchronized ku-band heterodyne FMCW radar | |
| CN112684421A (en) | Coherent calibration source system for linear frequency modulation continuous wave radar | |
| CN111257655A (en) | Intercepted distance testing device for radio frequency sensor | |
| CN113835070A (en) | Radar tactical performance detection and anti-interference capability evaluation simulator | |
| Shi et al. | Wuhan ionospheric oblique-incidence sounding system and its new application in localization of ionospheric irregularities | |
| US6484124B1 (en) | System for measurement of selected performance characteristics of microwave components | |
| CN105024770B (en) | Quantitative testing for sensitivity of a non-coherent FMCW autodyne receiver | |
| CN112859023A (en) | Calibration system of phased array weather radar | |
| CN113109771B (en) | Calibration device for calibration instrument and true value calibration method for weather radar echo intensity | |
| Gong et al. | Design and application of the digital multifunctional ionosonde | |
| CN107728101B (en) | Angular precision calibration method for microwave landing simulator | |
| CN113608183B (en) | Hypersonic broadband radio frequency target simulation system | |
| CN111856520A (en) | Time delay measuring system of satellite navigation receiver | |
| CN215599350U (en) | Calibration device of weather radar foundation active calibration instrument |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination |