CN102621556A - Laser ranging method for frequency modulation and phase measurement - Google Patents
Laser ranging method for frequency modulation and phase measurement Download PDFInfo
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- CN102621556A CN102621556A CN201210122949XA CN201210122949A CN102621556A CN 102621556 A CN102621556 A CN 102621556A CN 201210122949X A CN201210122949X A CN 201210122949XA CN 201210122949 A CN201210122949 A CN 201210122949A CN 102621556 A CN102621556 A CN 102621556A
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Abstract
The invention relates to a laser ranging method for frequency modulation and phase measurement and belongs to the technical field of laser. The advantages of high precision and high real-time properties of phase ranging are combined with the advantage of high interference resistance of frequency modulation ranging; and moreover, the problems of laser ranging on application occasions which are high in optical transmission environment interference and high in real-time ranging requirements and ranging precision and in which high-speed moving objects can be ranged are well solved, and the invention has the advantages of high ranging real-time properties, high optical transmission environment interference resistance, narrow signal processing bandwidth, continuously adjustable fixed distance, low cost, simple structure, high realizability by engineering and the like, and the method is hardly influenced by Doppler frequency, is particularly suitable for short-range laser ranging and has a good application prospect.
Description
Technical field
The present invention relates to a kind of frequency modulation and survey the phase laser distance measurement method, belong to laser technology field.
Background technology
LDMS generally adopts dual mode to find range: pulsed laser ranging and continuous wave laser range finding.
The impulse method range finding is that the laser that range measurement system is launched is received by the range finding system again after the reflection of measured target; Range measurement system is the round time of recording laser simultaneously; Half of the product of the light velocity and two-way time; Be exactly the distance between range measurement system and the measured target, the impulse method distance accuracy is low and have apart from the blind area, is not suitable for the closely application scenario of precision distance measurement.
The continuous wave laser range finding is divided into linear frequency modulation continuous wave (FMCW) method and Amplitude Modulation Continuous Wave (AMCW) phase ranging method; The modulating frequency of FMCW telemetry through transmission Laser Measurement two-way time changes obtains target information; This method emission coefficient and receiving system need bigger bandwidth; And system complex is subject to the influence of Doppler frequency when the measurement high speed moving target; The AMCW method is utilized the frequency of radio wave band that laser beam is carried out amplitude modulation(PAM) and is measured modulated laser and comes and goes the phase delay that is produced; Converse this for postponing the distance of representative according to the light modulated wavelength again; High but the anti-light transmission environmental disturbances ability of this method precision, and when the measurement high speed moving target, be subject to the Doppler frequency influence.
Existing laser distance measurement method is big in the light transmission environmental disturbances, the range finding real-time is required high and can find range to high-speed moving object and be not subject to be difficult to satisfy application need in the application of some occasion (for example laser PF) of Doppler frequency influence.
Summary of the invention
The objective of the invention is that existing to survey the phase laser ranging technique not high and be subject to the problem of Doppler frequency influence to the high-speed moving object distance accuracy under perturbation light transmission environment in order to solve, provide the frequency modulation of a kind of high anti-interference, high distance accuracy and high real-time to survey LDMS mutually.
The present invention realizes through following steps:
Step 1 produces the first via sinusoidal electric signals and the second tunnel sinusoidal electric signals that are used to find range, and two paths of signals is with the frequency homophase;
The first via sinusoidal electric signals that step 2, step 1 produce number is carried out frequency modulation to high-frequency carrier telegraphy, obtains the frequency modulation electric signal, the input laser driver;
Step 3, laser driver are when receiving the frequency modulation electric signal, and be luminous according to the Changing Pattern exciting laser pipe of frequency modulation electric signal, obtains the laser of light intensity according to the frequency modulation change in electric;
Step 4, optical transmitting system carries out beam shaping to the laser that step 3 obtains, and emission of lasering beam;
Step 6, photodetector is converted into electric signal with laser signal, delivers to FM demodulator, obtains the sinusoidal electric signals that phase place changes, and carries out analog to digital conversion then and obtains digital signal;
Step 7 after the second tunnel sinusoidal electric signals that step 1 is produced is carried out analog to digital conversion, is carried out digital phase demodulation with the digital signal that step 6 obtains, and obtains range information.Accomplish the laser ranging process.
Beneficial effect
The inventive method is got up the advantages of the high anti-jamming capacity of the high precision of phase ranging and high real-time advantage and frequency modulation range finding; Solved preferably big in the light transmission environmental disturbances, the range finding real-time is required height and distance accuracy is high, and the application scenario laser ranging problem down that can find range to high-speed moving object, have that the range finding real-time is high, anti-light transmission environmental disturbances ability by force, is not subject to the Doppler frequency influence, the signal Processing bandwidth is little, spacing apart from continuously adjustable, cost is low, simple in structure, be easy to advantage such as Project Realization.Short range laser ranging in being particularly useful for has a good application prospect.
Description of drawings
Fig. 1 is the process flow diagram of the inventive method;
Fig. 2 is that the frequency modulation of embodiment is surveyed phase LDMS structural representation;
Fig. 3 is the simulated experiment analogous diagram of the inventive method of embodiment; Wherein, Fig. 3 .1 is the FM signal of emission, the FM signal of reception, sinusoidal signal, the filtered sinusoidal signal of reception back demodulation; Fig. 3 .2 is a phase detector identified result and to the filtered result of identified result; Fig. 3 .3 is the range finding resultant error.
Embodiment
For objects and advantages of the present invention are described better, the present invention is further specified below in conjunction with accompanying drawing and embodiment.
The operating process of the inventive method is as shown in Figure 1.
Under Matlab develops software environment; The inventive method is carried out emulation; Simulation process is: writing m file analog signal generator generated frequency is the 5MHz sinusoidal signal, and this signal is that the high frequency carrier of 500MHz carries out frequency modulation and obtains FM signal to frequency, and this FM signal is added noise signal; Be used for the interference that the simulated laser transmission course receives, signal to noise ratio (S/N ratio) is made as 14dB; The target setting distance is 10m; Automatically calculate in view of the above and have the echo sinusoidal signal mathematic(al) representation that phase place has changed; This signal is carried out amplitude limit and filtering, and filtering and amplitude limit in order to the analog photoelectricity detector carries out carry out demodulation to the signal after handling again and restore the 5MHz sinusoidal signal; This sinusoidal signal and the initial sinusoidal signal that produces are quantized; The sample quantization function of simulation analog to digital converter utilizes digital phase demodulation method that the two-way sinusoidal signal is carried out digital phase demodulation at last, calculates distance.Fig. 3 .1 is the FM signal of emission, the FM signal of reception, sinusoidal signal, the filtered sinusoidal signal of reception back demodulation; Fig. 3 .2 is a phase detector identified result and to the filtered result of identified result; Fig. 3 .3 is the range finding resultant error.
Design a kind of frequency modulation according to the inventive method and survey the phase LDMS; Comprise sinusoidal signal generator, signal processor, frequency interleaved modulation modulator, FM demodulator, laser driver, photodetector, optical transmitting system, receiving optics, first analog to digital converter and second analog to digital converter, as shown in Figure 2.The output of sinusoidal signal generator connects the frequency interleaved modulation modulator and first analog to digital converter respectively, and optical transmitting system is delivered in the output of frequency interleaved modulation modulator behind laser driver, and signal processor is delivered in the output of first analog to digital converter; The output of receiving optics is connected to photodetector, and its output connects FM demodulator, delivers to signal processor through second analog to digital converter then.
(1) signal processor can be made up of FPGA, DSP, single-chip microcomputer and peripheral related device, can carry out phase demodulation, range information extraction with echoed signal to transmitting, produce or control outside DDS device generation sine wave.
(2) frequency interleaved modulation modulator and FM demodulator carry out frequency modulation and demodulation to modulation signal.
(3) laser driver is a light signal with sinusoidal frequency modulation electrical signal conversion, and the exciting laser pipe produces the laser signal that light intensity receives this signal modulation.
(4) photodetector converts the light signal that receives electric signal into and carries out amplification and filtering, the amplitude limit of signal.
(5) optical transmitting system and receiving optics are respectively applied for the Laser emission signal are carried out beam shaping and the laser signal that receives is converged to photodetector.
Sinusoidal signal generator in the present embodiment adopts Direct Digital frequency synthesis (DDS) AD9850 chip; Signal processor adopts the ALTERA EP3C10E144C8FPGA of company chip; The two-way analog to digital converter adopts the ADI dual channel high speed analog to digital converter AD9218 of company chip, adopts phaselocked loop (PLL) FM circuit and frequency modulation demodulation circuit and APD photodetection circuit.
At first produce the sinusoidal simulating signal of two-way with the frequency homophase by fpga chip control Direct Digital frequency synthesis chip; The first via is delivered to the phaselocked loop FM circuit and is produced sinusoidal FM signal; Amplify through laser drive circuit then, the excitation continuous wave laser diode produces the laser signal that light intensity changes with CW with frequency modulation, and this signal shines target after via the optical transmitting system shaping and reflects; Part laser signal energy enters into receiving optics; Converge to APD photodetection circuit, behind APD photodetection circuit amplification filtering and amplitude limit, deliver to and carry out demodulation in the phaselocked loop frequency modulation demodulation circuit; Restore sinusoidal simulating signal; Compare with the sinusoidal signal that FPGA before the emission produces, variation has taken place in this sine wave phase, is to deliver to the phase detector among the FPGA after the digital signal with it through analog-digital conversion ic sample quantization; The second the tunnel gives the phase detector among the FPGA after converting digital signal into through the analog to digital conversion integrated chip; FPGA carries out digital phase demodulation to two paths of signals, calculates distance value.
The frequency modulation of present embodiment is surveyed the phase LDMS to be applied in the outdoor experimental situation of greasy weather of an atmospheric visibility 200m; This static target of standard reflecting plate to detection range 10m place is found range; Wherein standard reflecting plate is perpendicular to ground, and light reflectivity is 20%.The emission light beam vertical irradiation of the LDMS of present embodiment records through spectrum analyzer that the signal to noise ratio (snr) of FM signal is about 10dB after the opto-electronic conversion to standard reflecting plate, the result that finds range this moment is 10.12m, and error is 0.12m.Target range is increased, and every separated 2m once tests, and measurement result is as shown in the table:
| Distance (unit: m) | Signal to noise ratio (S/N ratio) (unit: dB) | Distance measure (unit: m) | Error (unit: m) |
| 10 | About 10 | 10.12 | 0.12 |
| 12 | About 10 | 11.91 | 0.09 |
| 14 | About 9 | 14.13 | 0.13 |
| 16 | About 8 | 16.18 | 0.18 |
| 18 | About 6 | 18.21 | 0.21 |
The present invention serves as the utilization background with the range finding of CW with frequency modulation laser fuze, short range laser ranging in can be applicable to.This system is hidden in the range information of target in the phase place of sinusoidal modulation signal; Little with the amplitude relation of laser signal, therefore be not subject to the influence of light transmission environment, and bandwidth is narrower; Basically there is not the influence of parastic modulation; Therefore the simple and realization easily of signal Processing, transmit and the phase differential of echoed signal that final range finding utilizes are found range, so the distance accuracy height.
More than combine the accompanying drawing specific embodiments of the invention to be described; But these explanations can not be understood that to have limited scope of the present invention; Protection scope of the present invention is limited the claims of enclosing, and any change on claim of the present invention basis all is protection scope of the present invention.
Claims (4)
1. a frequency modulation is surveyed the phase laser distance measurement method, it is characterized in that: comprise the steps:
Step 1 produces the first via sinusoidal electric signals and the second tunnel sinusoidal electric signals that are used to find range;
The first via sinusoidal electric signals that step 2, step 1 produce number is carried out frequency modulation to high-frequency carrier telegraphy, obtains the frequency modulation electric signal, the input laser driver;
Step 3, laser driver are when receiving the frequency modulation electric signal, and be luminous according to the Changing Pattern exciting laser pipe of frequency modulation electric signal, obtains the laser of light intensity according to the frequency modulation change in electric;
Step 4, optical transmitting system carries out beam shaping to the laser that step 3 obtains, and emission of lasering beam;
Step 5, laser beam irradiation are after target, and part energy reflected back receiving optics converges to photodetector;
Step 6, photodetector is converted into electric signal with laser signal, delivers to FM demodulator, obtains the sinusoidal electric signals that phase place changes, and carries out analog to digital conversion then and obtains digital signal;
Step 7 after the second tunnel sinusoidal electric signals that step 1 is produced is carried out analog to digital conversion, is carried out digital phase demodulation with the digital signal that step 6 obtains, and obtains range information; Accomplish the laser ranging process.
2. a kind of frequency modulation according to claim 1 is surveyed the phase laser distance measurement method, it is characterized in that: the described first via sinusoidal electric signals of step 1 and the second tunnel sinusoidal electric signals are with the frequency homophase.
3. a kind of frequency modulation according to claim 1 is surveyed the phase laser distance measurement method; It is characterized in that: a kind of frequency modulation of the said method of performing step one to step 7 is surveyed the phase LDMS, comprises sinusoidal signal generator, signal processor, frequency interleaved modulation modulator, FM demodulator, laser driver, photodetector, optical transmitting system, receiving optics, first analog to digital converter and second analog to digital converter; The output of sinusoidal signal generator connects the frequency interleaved modulation modulator and first analog to digital converter respectively, and optical transmitting system is delivered in the output of frequency interleaved modulation modulator behind laser driver, and signal processor is delivered in the output of first analog to digital converter; The output of receiving optics is connected to photodetector, and its output connects FM demodulator, delivers to signal processor through second analog to digital converter then.
4. a kind of frequency modulation according to claim 1 is surveyed the phase laser distance measurement method, it is characterized in that: short range laser ranging in being applicable to.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103744176A (en) * | 2014-01-21 | 2014-04-23 | 武汉虹识技术有限公司 | Liquid lens focusing system and method based on phase-locked ring |
| CN105785385A (en) * | 2016-04-15 | 2016-07-20 | 中国科学院上海技术物理研究所 | Laser ranging method and device based on synchronous sampling and multiple phase measurement |
| CN105842708A (en) * | 2016-06-21 | 2016-08-10 | 昆山穿山甲机器人有限公司 | Robot photoelectric ranging anti-collision system for preventing background light interference and robot photoelectric ranging anti-collision method thereof |
| CN106249246A (en) * | 2016-07-21 | 2016-12-21 | 湖南拓视觉信息技术有限公司 | Distance-finding method and device, measuring circuit |
| WO2017113245A1 (en) * | 2015-12-30 | 2017-07-06 | 深圳市柔宇科技有限公司 | Automatically-adjustable head-mounted display device and adjustment method therefor |
| WO2017181453A1 (en) * | 2016-04-20 | 2017-10-26 | 深圳市速腾聚创科技有限公司 | Laser ranging system and method employing time domain waveform matching technique |
| CN110187351A (en) * | 2019-05-22 | 2019-08-30 | 北京石油化工学院 | A kind of digital laser distance measuring method using high frequency pulse-amplitude modulation wave |
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| CN101187556A (en) * | 2007-12-13 | 2008-05-28 | 北京理工大学 | Optical fiber distance measuring method and device |
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| CN101187556A (en) * | 2007-12-13 | 2008-05-28 | 北京理工大学 | Optical fiber distance measuring method and device |
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Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103744176A (en) * | 2014-01-21 | 2014-04-23 | 武汉虹识技术有限公司 | Liquid lens focusing system and method based on phase-locked ring |
| WO2017113245A1 (en) * | 2015-12-30 | 2017-07-06 | 深圳市柔宇科技有限公司 | Automatically-adjustable head-mounted display device and adjustment method therefor |
| CN105785385A (en) * | 2016-04-15 | 2016-07-20 | 中国科学院上海技术物理研究所 | Laser ranging method and device based on synchronous sampling and multiple phase measurement |
| WO2017181453A1 (en) * | 2016-04-20 | 2017-10-26 | 深圳市速腾聚创科技有限公司 | Laser ranging system and method employing time domain waveform matching technique |
| US11592553B2 (en) | 2016-04-20 | 2023-02-28 | Suteng Innovation Technology Co., Ltd | Distance measurement system and method using lidar waveform matching |
| CN105842708A (en) * | 2016-06-21 | 2016-08-10 | 昆山穿山甲机器人有限公司 | Robot photoelectric ranging anti-collision system for preventing background light interference and robot photoelectric ranging anti-collision method thereof |
| CN106249246A (en) * | 2016-07-21 | 2016-12-21 | 湖南拓视觉信息技术有限公司 | Distance-finding method and device, measuring circuit |
| CN106249246B (en) * | 2016-07-21 | 2018-12-21 | 湖南拓视觉信息技术有限公司 | Distance measuring method and device, measuring circuit |
| CN110187351A (en) * | 2019-05-22 | 2019-08-30 | 北京石油化工学院 | A kind of digital laser distance measuring method using high frequency pulse-amplitude modulation wave |
| CN110187351B (en) * | 2019-05-22 | 2021-06-22 | 北京石油化工学院 | Digital laser ranging method using high-frequency pulse amplitude modulation wave |
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Application publication date: 20120801 |