CN1295486C - Non-linear evolutional correction method for levelmeter of linear frequency-modulation radar - Google Patents
Non-linear evolutional correction method for levelmeter of linear frequency-modulation radar Download PDFInfo
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Abstract
The present invention relates to a non-linear evolutional correction method for a linear frequency modulation radar level meter, and belongs to the technical fields of signal processing and automatic measurement. A frequency sweep voltage curve for controlling a voltage controlled oscillator is segmented, characteristic information is extracted by using spectral analysis, end point coordinates of the segmenting curve are obtained through an evolutional calculation principle, and the non-linear frequency sweep curve is formed to compensate the nonlinearity of the voltage controlled oscillator. The present invention can generate linear frequency modulation signal with high linearity without measuring the frequency or the phase of a microwave signal with high frequency, solve the non-linear problem of the frequency modulation of the linear frequency-modulated radar, ensure the measurement precision, can be suitable for the measurement of various phases, have no need of adding special circuits for linearity correction, and have low cost.
Description
One, technical field
Non-linear evolutional correction method for levelmeter of linear frequency-modulation radar of the present invention belongs to signal Processing and automatic measurement technology field, be a kind of spectrum analysis characteristic information extraction that utilizes specifically, adopt the principle of evolutionary computation to solve the nonlinear problem of linear FM radar frequency modulation.
Two, technical background
LINEAR CONTINUOUS frequency modulation radar body place meter has noncontact, resolution height in level gauging, the advantage of medium wide adaptability is widely used in various level gaugings.Because the voltage controlled oscillator that uses in the LINEAR CONTINUOUS ripple frequency modulated(FM) radar has the non-linear of essence, when adopting linear fully voltage to carry out frequency modulation (PFM), can make the frequency signal of final output present nonlinear characteristic, owing to there is frequency shift (FS), Beat Signal after the mixing is not the simple signal under the ideal linearity FM signal situation, frequency spectrum is with broadened, thereby cause LFMCW radar level gauge resolution to reduce, also can cause the decline of signal to noise ratio (S/N ratio) after the FFT spectrum analysis simultaneously, influence final computational accuracy.Non-linear in order to eliminate, generally adopt 2 kinds of methods: open loop correction and closed-loop corrected.Open loop correction is to measure the electric voltage frequency relation of VCO in advance, is stored in the storer, and the digital quantity by storage in advance during actual the use is carried out the output of sweep voltage by D/A converter.Or utilize potentiometer and amplifier to constitute the hardware circuit of the gamma correction of multistage, and to carry out hardware correctedly, the shortcoming of these two kinds of methods is that the characteristic of each VCO is all inequality, workload is very big in the production debug process, is difficult for mass production.Temperature influence is also very big in the actual use, is difficult to guarantee measuring accuracy.Closed-loop corrected method is that the measuring method of employing frequency or phase place is obtained the frequency under the corresponding voltage, then the digital quantity that produces control voltage is revised, and to obtain the satisfied linearity, this will increase the workload of hardware cost and software.
In order to address this problem, it is synthetic that the method that people adopt the synthetic and digital phase-locked loop of Direct Digital is carried out numeral to needed signal, but can not drop into the application of reality owing to following reason.At first adopt the synthetic method of Direct Digital also not reach the X-band of fill level radar work at present, can only adopt the method for frequency multiplication or up-conversion, this method one is that cost is too high, system complex, the 2nd, the microwave signal that produces through frequency multiplication has a lot of harmonic components, phase noise is big, can produce negative influence to measurement result.In addition, need a transient process when utilizing phaselocked loop to change frequency, so its frequency inverted time is longer, and can not satisfies the requirement of the high speed frequency sweep characteristic of linear frequency modulation ripple radar.
Three, summary of the invention
Non-linear evolutional correction method for levelmeter of linear frequency-modulation radar purpose of the present invention is: provide a kind of easy and need not increase the bearing calibration of the fm linearity of any hardware, solve the problem of the difficult and more complicated of present linearity correction, solve because the problem of the non-linear influence that measuring accuracy is brought of frequency modulation, a kind of radar levelmeter of producing and debugging be convenient to is provided.
Non-linear evolutional correction method for levelmeter of linear frequency-modulation radar of the present invention, utilize the evolution principle to the frequency modulation of the voltage controlled oscillator in the radar levelmeter non-linear carry out closed-loop corrected, it is characterized in that: the non-linear frequency modulation that remedies voltage controlled oscillator that utilizes the fm voltage curve is non-linear, the fm voltage curve is divided into plurality of sections, every section end points coordinate is divided certain region of variation, adopt the evolution principle to ask for the end points coordinate of corresponding best fm linearity, with the fm voltage curve after each end points connection can formation correction; Need not measure the frequency or the phase place of high-frequency microwave signal, ask for evaluation function in the evolution principle, realize the nonlinear correction of voltage controlled oscillator frequency modulation by extracting the difference frequency signal spectrum signature; Adopt the fm linearity of the method raising voltage controlled oscillator of overlapping analysis; Specifically, the hardware foundation of the linearity evolution bearing calibration of LFMCW radar levelmeter voltage controlled oscillator of the present invention mainly comprises digital signal processing unit and microwave unit [structure sees Fig. 1 for details], digital signal processing unit is by keyboard display communication interface module 1, D/A converter 2, digital signal processor 3, buffer amplifier 4, storer 5, wave filter 12, digital program controlled gain amplifier 13 and high-speed a/d converter 14 are formed, microwave unit is by voltage controlled oscillator 6, coupling mechanism 7, antenna 9, circulator 10 and frequency mixer 11 are formed, digital signal processor 3 output digital quantity signals are given D/A converter 2, convert voltage signal to, form the control voltage of the voltage controlled oscillator 6 of microwave unit through buffer amplifier 4, excitation voltage controlled oscillator 6 produces the microwave FM signal, the microwave FM signal is passed through coupling mechanism 7 after circulator 10 is launched by antenna 9, the signal that coupling mechanism 7 is coupled out is simultaneously delivered to frequency mixer 11 as the reference signal, target object 8 reflection echos receive through antenna 9, behind circulator 10, also be sent to frequency mixer 11 and reference signal mixing, signal after the mixing forms difference frequency signal by low-pass filter 12 backs, difference frequency signal is sampled by high-speed a/d converter 14 by digital program controlled gain amplifier 13 backs, converting Serial No. to is read by digital signal processor 3, storage in storer 5,3 pairs of sampled digital sequences of digital signal processor are carried out FFT or small echo computing and analysis, extract the non-linear characteristics amount of representing;
There is non-linear [the seeing Fig. 3] of essence in voltage controlled oscillator, among Fig. 3 desirable frequency modulation transmit 18 and desirable echoed signal 20 mixing after be point-frequency signal, actual frequency modulation transmits and 17 has nonlinear characteristic, actual ghosts signal 19 also has nonlinear characteristic, will make spectral aliasing after the two phase mixing, make the resolution of measurement reduce the position that maybe can't differentiate concrete target object, spectrum peak 21 is corresponding concrete thing positions among Fig. 4, there are two peak points 22 and 23 in adjacent very near position, might cause to differentiate concrete material position, this is a kind of reasonable situation in laboratory measurement, will be more serious in the actual measurement process, Fig. 5 is the frequency spectrum that adopts after method of the present invention is proofreaied and correct the linearity, except that the spectrum peak 24 of representative position, other composition is effectively suppressed, and the phase noise of VCO and the non-linear influence that brings are eliminated, and the non-linear evolution bearing calibration of linear FM radar level meter voltage controlled oscillator of the present invention is adopted based on the principle of evolvement method the frequency modulation voltage curve is carried out the piecewise linearity correction, concrete way is, the fm voltage curve is divided into plurality of sections, among Fig. 6 the frequency modulation curve is divided into six sections, be respectively line segment 25, line segment 26, line segment 27, line segment 28, line segment 29, line segment 30, have seven end points, be respectively starting point 31, terminal point 37 and the middle variable end-point 32 that is assigned Variable Area, 33,34,35,36, starting point 31 and terminal point 37 are changeless point, connect each end points and form a nonlinear fm voltage curve, the non-linear of voltage controlled oscillator compensated, every section end points adopts the method for evolving to obtain, and by the frequency spectrum after FFT or the small echo computing is analyzed, obtains to represent the characteristic quantity of non-linear and interfere information, the concrete thing position of 21 correspondences, spectrum peak among Fig. 4, be to need in the measuring process, and two other peak point 22 and 23 is phase noise and non-linear causing by VCO, need be inhibited, can select to compose in peak and spectrum both sides, the peak certain limit several peak values the merchant's and as estimating the non-linear evaluation function that impacts, make this function reach certain numerical value by evolvement method, can effectively suppress the phase noise and the non-linear influence that causes of frequency modulation of voltage controlled oscillator, the numerical value at spectrum peak 21 and spectrum peak 22 among for example optional Fig. 4,23 numerical value the merchant's and as evaluation function, evaluation to the evolution calibration result, the method of proofreading and correct of evolving sees Fig. 9 for details, the coding colony of variable end-point coordinate in the middle of first subprocess 43 after trimming process begins among Fig. 9 is used for producing at random in the variable end-point region of variation in the middle of each, and coding can adopt binary coding or other coding form, the figure place of coding can be determined as required, the quantity of individual in population is N, and the quantity of population determines that as required the quantity of variable is M in the individuality, quantity decision by curve segmentation, thereafter subprocess 44 is with the loop variable zero clearing, and subprocess 45 converts the encoded radio of each end points of curve in the individuality to coordinate figure, and subprocess 46 is with starting point, variable end-point in the middle of each, terminating point connects together, generate the sweep voltage curve, this curve is actually a digital quantity sequence, and subprocess 47 is exported the digital quantity sequence with predetermined speed continuously by D/A converter 2, produces the sweep voltage curve to voltage controlled oscillator 6, control voltage controlled oscillator 6 output microwave FM signal, through coupling mechanism 7, circulator 10, antenna 9 is transmitted into a planar metal thin plate, and the reflection echo signal that antenna 9 receives enters frequency mixer 11 and carries out mixing by the reference frequency signal that coupling mechanism 7 is coupled out through circulator 10, and the mixed frequency signal of generation forms difference frequency signal through wave filter 12 backs, after digital program controlled gain amplifier 13 amplifications or decay, carry out the Serial No. that sample quantization forms difference frequency signal by high-speed a/d converter 14 in subprocess 48, the Serial No. of 3 pairs of samplings of digital signal processor carries out FFT computing or wavelet analysis in subprocess 49, obtains spectrum curve, carry out the Characteristic Extraction of curve, thereafter subprocess 50 is used for calculating the performance evaluation function of this sweep voltage curve, and subprocess 51 judges whether evaluation function satisfies predetermined requirement, if meet the demands then by subprocess 52 saving results, finish trimming process, otherwise subprocess 53, the 54 pairs of loop variables increase progressively and judge, the curve of each individual representative can both be tested and estimate in the colony that guarantees to encode, and carry out evolutionary computation by evolutionary computation subprocess 55 after initial population test and evaluation are finished, the result clusters body weight that is produced is carried out above-mentioned test and evaluation procedure again, thick line sweep voltage curve 38 among Fig. 7 has been represented the sweep voltage curve after overcorrect, and sweep voltage curve 38 has been non-linear as can be seen, by the non-linear microwave FM signal of revising the non-linear acquisition high linearity of voltage controlled oscillator of sweep voltage curve 38, need to prove in the subprocess 55 and can adopt genetic algorithm, or other evolution algorithm is evolved such as thinking, evolutional programming, immunoevolution method etc., the selection of evaluation function also is diversified simultaneously, has divided 6 sections to the frequency modulation voltage curve among the present invention, the segmentation of adopting other quantity also is feasible, the many more calibration results of segmentation also can be got well, and improve the sampling rate of A/D conversion, obtain surpassing the sample sequence that FFT counts, employing is carried out overlapping FFT computing to original sample sequence, obtain a plurality of frequency spectrums of single frequency sweep curve, Fig. 8 has represented the crude sampling sequence is carried out overlapping segmentation thought in detail, for example can be divided into overlapped sequence length identical 39,40,41,42 data segments, each section is carried out the FFT computing, characteristic quantity on comprehensive a plurality of frequency spectrum is estimated, and can obtain the higher correction result of the linearity, but the increase that can bring operand.
Advantage of the present invention: be mainly used in industrial and mining enterprises various things position measurement and can be used for some range observation occasions.The correction of the linear frequency modulation linearity relies on level meter itself to carry out, need not external measurement devices and instrument, and correcting mode and algorithm are simple, proofread and correct back linearity height; The cost of instrument is low, produces and debugs simply, enhances productivity; The measuring accuracy height, error is little, antijamming capability is strong, adapt to abominable industrial environment, and is reliable and stable.
Four, description of drawings
Fig. 1 is the structural drawing of way of realization 1 of the present invention
Fig. 2 is the structural drawing of form 2 of the present invention
Fig. 3 is the nonlinear characteristic of voltage controlled oscillator
Frequency spectrum before Fig. 4 proofreaies and correct
Frequency spectrum after Fig. 5 proofreaies and correct
The segmentation of Fig. 6 sweep voltage curve
Fig. 7 proofreaies and correct back sweep voltage curve
The overlapping segmentation of Fig. 8 crude sampling sequence
Fig. 9 linearization correcting process figure
Figure 10 sweep voltage curve of correspondence as a result of evolving
Number in the figure
1, display keyboard communication interface 2, high-speed d/a converter
3, digital signal processor 4, buffer amplifier
5, storer 6, voltage controlled oscillator
7, coupling mechanism 8, target object or metal plate
9, antenna 10, circulator
11, frequency mixer 12, low-pass filter
13, digital program controlled gain amplifier 14, high-speed a/d converter
15, microwave delay line 16, microwave switch
17, the nonlinear properties 18 of actual transmission, desirable linearity transmit
19, the echo nonlinear properties 20 of actual reception, desirable echoed signal
21, the target peak in the spectrum curve 22, by the interference peak value of the non-linear generation of frequency modulation
23, by the interference peak value 24 of the non-linear generation of frequency modulation, the single peak value after the evolution linearity correction
25, sweep voltage curve segmentation 1 26, sweep voltage curve segmentation 2
27, sweep voltage curve segmentation 3 28, sweep voltage curve segmentation 4
29, sweep voltage curve segmentation 5 30, sweep voltage curve segmentation 6
31, in the middle of the sweep voltage curve starting point 32, sweep voltage curve variable end-point 1 and
Region of variation
33, in the middle of the sweep voltage curve in the middle of variable end-point 2 34, the sweep voltage curve variable end-point 3 and
And region of variation region of variation
35, in the middle of the sweep voltage curve in the middle of variable end-point 4 36, the sweep voltage curve variable end-point 5 and
And region of variation region of variation
37, the sweep voltage curve after sweep voltage curve terminating point 38, the correction
39, the overlapping segmentation 1 40 of crude sampling sequence, the overlapping segmentation 2 of crude sampling sequence
41, the overlapping segmentation 3 42 of crude sampling sequence, the overlapping segmentation 4 of crude sampling sequence
43, produce coding colony 44, the loop variable zero clearing of end points coordinate
45, the end points encoded radio converts end points 46 in the individuality, connection end point generates the frequency sweep curve
Coordinate figure
47, output sweep voltage curve 48, acquisition difference frequency signal sampled digital sequence
49, carry out the performance that frequency spectrum calculated and extracted spectrum signature 50, calculates the sweep voltage curve
Amount
51, judge whether the linearity reaches requirement 52, preserve and proofread and correct the result
53, loop variable increases progressively 54, whether judgement is estimated each individuality in the colony finishes
55, colony is carried out evolutionary computation
Five, embodiment
Table 1 initial population example
| Sequence number | Variable end- | Variable end- | Variable end- | Variable end-point 4 | Variable end-point 5 | |||||
| X1’ | Y1’ | X2’ | Y2’ | X3’ | Y3’ | X4’ | Y4’ | X5’ | Y5’ | |
| 1 | 16838 | 5202 | 26703 | 2750 | 28528 | 21293 | 1696 | 19975 | 413 | 23236 |
| 2 | 5758 | 9171 | 6270 | 879 | 23363 | 29441 | 18585 | 10519 | 26281 | 7254 |
| 3 | 10113 | 4434 | 13870 | 30989 | 21087 | 19484 | 13455 | 21472 | 12389 | 11688 |
| 4 | 17515 | 28317 | 11529 | 30134 | 19052 | 12759 | 92 | 19641 | 11357 | 5003 |
| 5 | 31051 | 24582 | 27499 | 29752 | 31235 | 15400 | 18288 | 9349 | 4887 | 32203 |
| 6 | 5627 | 6815 | 4500 | 28364 | 15109 | 6211 | 31755 | 23391 | 17532 | 8788 |
| 7 | 23010 | 4586 | 8607 | 4880 | 17075 | 4144 | 29167 | 30563 | 1555 | 23915 |
| 8 | 7419 | 9653 | 5808 | 5629 | 11755 | 15335 | 27412 | 22184 | 12299 | 1199 |
| 9 | 16212 | 26306 | 15725 | 2235 | 10675 | 22704 | 25030 | 19958 | 9490 | 13424 |
| 10 | 4086 | 7174 | 12457 | 21332 | 288 | 32520 | 31717 | 41 | 26460 | 24408 |
| 11 | 2749 | 18451 | 16542 | 24145 | 32053 | 23789 | 24842 | 27666 | 24911 | 6490 |
| 12 | 12767 | 23448 | 16474 | 3356 | 14157 | 32121 | 28572 | 23363 | 14183 | 27655 |
| 13 | 9084 | 6473 | 11531 | 5243 | 5758 | 21913 | 26393 | 25344 | 22704 | 21593 |
| 14 | 12060 | 32434 | 17222 | 3079 | 5222 | 23571 | 27828 | 2410 | 17412 | 13310 |
| 15 | 32225 | 8193 | 3952 | 3988 | 17488 | 12369 | 11805 | 28635 | 20961 | 3072 |
| 16 | 17543 | 14110 | 17024 | 807 | 18945 | 2770 | 3660 | 1006 | 20382 | 12038 |
| 17 | 25089 | 24748 | 19894 | 24979 | 10294 | 1594 | 5838 | 20068 | 3608 | 5087 |
| 18 | 21183 | 28210 | 24015 | 31357 | 11200 | 887 | 9046 | 26660 | 5811 | 1697 |
| 19 | 25137 | 29320 | 18247 | 914 | 5171 | 18093 | 18182 | 20562 | 7168 | 23526 |
| 20 | 25566 | 32049 | 11276 | 21187 | 14305 | 32317 | 23772 | 29323 | 20794 | 7448 |
| 21 | 26966 | 12956 | 26278 | 3540 | 7951 | 11188 | 12354 | 13764 | 12286 | 17497 |
| 22 | 4978 | 14162 | 19365 | 14022 | 6601 | 27640 | 15377 | 21307 | 13771 | 15802 |
| 23 | 20495 | 4166 | 8746 | 10149 | 23608 | 4295 | 14885 | 7773 | 27844 | 19649 |
| 24 | 10311 | 14997 | 21976 | 609 | 7214 | 12490 | 22759 | 10683 | 6684 | 30555 |
| 25 | 11367 | 7793 | 18092 | 29009 | 6377 | 25859 | 22934 | 9013 | 11255 | 25891 |
| 26 | 30054 | 32310 | 25851 | 24833 | 13865 | 3106 | 1903 | 8216 | 29227 | 1020 |
| 27 | 17031 | 21391 | 29088 | 16696 | 25369 | 24786 | 6159 | 28834 | 26960 | 18267 |
| 28 | 13145 | 19799 | 29163 | 5432 | 27215 | 17097 | 26145 | 15571 | 27448 | 14366 |
| 29 | 19882 | 7926 | 2231 | 24999 | 8030 | 5062 | 10045 | 15241 | 9086 | 23408 |
| 30 | 25736 | 14905 | 26233 | 28863 | 177 | 27943 | 26847 | 2303 | 8526 | 12848 |
| 31 | 30524 | 25885 | 29732 | 16369 | 16849 | 31247 | 17401 | 24754 | 1211 | 29762 |
| 32 | 28505 | 2582 | 21106 | 28676 | 11337 | 12292 | 29783 | 928 | 26131 | 22042 |
| 33 | 28394 | 15610 | 5411 | 24077 | 2699 | 16846 | 4167 | 3417 | 8645 | 23252 |
| 34 | 22102 | 5000 | 9874 | 7701 | 23099 | 3962 | 781 | 32048 | 11552 | 31440 |
| 35 | 24851 | 8052 | 5448 | 1691 | 8531 | 28479 | 24287 | 12018 | 18627 | 21810 |
The row curve.With these frequency sweep curve negotiating D/A converter 2 outputs, can obtain linear modulation frequency.Can enter normal metering system after proofreading and correct end, be installed to the scene.Therefore, adopting method of the present invention to proofread and correct at the scene also is very easily.During normal the use, calculate real material level signal, utilize the mode that shows via display keyboard communication interface unit 1, or export to outside Displaying Meter, or communicate the transmission data by communication interface and outside Displaying Meter by electric current;
Table 2 is proofreaied and correct the result
| Starting point | Variable end- | Variable end- | Variable end- | Variable end-point 4 | Variable end-point 5 | Terminal point | ||||||||
| X0 | Y0 | X1 | Y1 | X2 | Y2 | X3 | Y3 | X4 | Y4 | X5 | Y5 | X6 | Y6 | |
| The shaping value of binary coding correspondence | Do not have | Do not have | 13061 | 4002 | 3410 | 9286 | 11470 | 12125 | 5166 | 5896 | 15445 | 21762 | Do not have | Do not have |
| Coordinate | 0 | 0 | 2170 | 2608 | 4223 | 4677 | 6601 | 6820 | 8714 | 9240 | 11133 | 10986 | 13383 | 13383 |
Claims (1)
1. non-linear evolutional correction method for levelmeter of linear frequency-modulation radar, utilize the evolution principle to the frequency modulation of the voltage controlled oscillator in the radar levelmeter non-linear carry out closed-loop corrected, it is characterized in that: the non-linear frequency modulation that remedies voltage controlled oscillator that utilizes the fm voltage curve is non-linear, the fm voltage curve is divided into plurality of sections, every section end points coordinate is divided certain region of variation, adopt the evolution principle to ask for the end points coordinate of corresponding best fm linearity, with the fm voltage curve after each end points connection can formation correction; Need not measure the frequency or the phase place of high-frequency microwave signal, ask for evaluation function in the evolution principle, realize the nonlinear correction of voltage controlled oscillator frequency modulation by extracting the difference frequency signal spectrum signature; Adopt the fm linearity of the method raising voltage controlled oscillator of overlapping analysis.
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| FR2917166B1 (en) * | 2007-06-05 | 2012-04-27 | Toulouse Inst Nat Polytech | METHOD AND DEVICE FOR DETECTING WATER IN AN ALVEOLAR STRUCTURE. |
| CN101110565B (en) * | 2007-06-28 | 2010-04-14 | 安徽蓝盾光电子股份有限公司 | Linearity correcting device for radar voltage controlled oscillator collecting vehicle information |
| CN102540262B (en) * | 2010-12-27 | 2013-10-30 | 中国电子科技集团公司第五十研究所 | Nonlinear node detector |
| US8505382B2 (en) | 2011-02-10 | 2013-08-13 | Ut-Battelle, Llc | Nonlinear nanomechanical oscillators for ultrasensitive inertial detection |
| DE102011007372B4 (en) * | 2011-04-14 | 2023-05-04 | Endress+Hauser SE+Co. KG | Calibration and/or monitoring method for FMCW radar level gauges |
| CN102901954A (en) * | 2012-09-04 | 2013-01-30 | 天津职业技术师范大学 | Non-linear software correction method of linear frequency modulated continuous wave radar |
| CN104079269B (en) * | 2014-05-30 | 2016-08-17 | 中国电子科技集团公司第十研究所 | Microwave VCO directly modulation High Linear FM signal generation circuit |
| CN107765239A (en) * | 2016-08-22 | 2018-03-06 | 邹谋炎 | A kind of design and implementation method of economical short distance range radar |
| CN110243436B (en) * | 2019-07-08 | 2020-05-19 | 智驰华芯(无锡)传感科技有限公司 | Close-range interference signal eliminating system for radar level meter |
| CN111325238B (en) * | 2020-01-21 | 2023-06-09 | 全球能源互联网研究院有限公司 | Phase noise compensation method and system |
| CN114994653A (en) * | 2020-03-20 | 2022-09-02 | 华为技术有限公司 | Beat frequency signal processing method and device |
| CN111175696A (en) * | 2020-04-10 | 2020-05-19 | 杭州优智联科技有限公司 | Single-base-station ultra-wideband AOA (automatic optical inspection) positioning method based on frequency modulated continuous waves |
| CN114900606B (en) * | 2022-03-31 | 2024-01-05 | 浙江华创视讯科技有限公司 | Calibration method and device for zoom tracking curve, electronic device and storage medium |
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| DE19713967A1 (en) * | 1997-04-04 | 1998-10-08 | Siemens Ag | Distance measurement device using FMCW radar |
| CN1243243A (en) * | 1999-06-18 | 2000-02-02 | 中国科学院上海技术物理研究所 | Linear frequency-modulation continuous wave radar feed location instrument and measuring method thereof |
| US6204803B1 (en) * | 1999-05-28 | 2001-03-20 | Mitsubishi Denki Kabushiki Kaisha | Radar apparatus |
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| DE19713967A1 (en) * | 1997-04-04 | 1998-10-08 | Siemens Ag | Distance measurement device using FMCW radar |
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