CN100510775C - Method for ultrasonic distance measuring under low signal-to-noise ratio and range finder thereof - Google Patents
Method for ultrasonic distance measuring under low signal-to-noise ratio and range finder thereof Download PDFInfo
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- CN100510775C CN100510775C CNB2006101491701A CN200610149170A CN100510775C CN 100510775 C CN100510775 C CN 100510775C CN B2006101491701 A CNB2006101491701 A CN B2006101491701A CN 200610149170 A CN200610149170 A CN 200610149170A CN 100510775 C CN100510775 C CN 100510775C
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Abstract
The invention discloses an ultrasonic ranging method and the range finder in the low SNR which can be used in water, rain and snow and fog day. It is made up of the measured object and ultrasonic rang finder. The transmitting transducer of the ultrasonic range finder sends an ultrasonic signal to the measured object and then receives the reflected ultrasonic signal from the measured object. The distance track ring can get the estimated value tao of the reflecting signal compared to the emitting signal to get the object distance which is also the main character of the invention. It can clean out the environment noise influence and has the good detecting, anti-jamming ability and the precision. The device is especially proper for the in water, rain and snow and fog day.
Description
Technical field: range observation
The present invention relates to a kind of system that utilizes hyperacoustic reflection measurement distance, particularly relate to the method that a kind of " distance tracking loop " realizes ultrasonic distance measuring under low signal-to-noise ratio.
Background technology:
The river middle and lower reaches cause the decline of the pondage in river because the mud of piling up has improved the height in riverbed gradually.In order to obtain the pondage in river easily, need to measure the height of riverbed to the water surface.Can adopt the boat-carrying ultrasonic range finder, ship laterally streaks the river, utilizes the distance of the ultrasonic range finder section test water surface to the riverbed.General known range finding all adopts electromagenetic wave radiation or reflection to carry out, but electromagnetic wave is absorbed by the water medium easily under water and decays, and can't penetrate water layer, and sound wave can overcome this problem, can adopt ultrasound wave to carry out undersea ranging.Under inclement weather environment such as sleet, dense fog, adopt ultrasound wave to carry out range observation, also can obtain good effect.
Supersonic sounding or pulsed radar range finding all are as modulated wave with square profiled pulses modulating wave, launch to measured target by transmitting transducer, its reflection wave is received by receiving transducer, be emitted to the needed journey time of measured target round trip according to ultrasound wave self-emission transducer, determine the distance of target.When being used to find range, the ultrasonic range finder of hull bottom is launched an acoustic signals s vertically downward in water
1(t), signal is reflected by the riverbed, and ultrasonic range finder just receives reflected signal s
2(t),, obtain the propagation delay time τ of signal through than circuitry phase, so can obtain distance:
Wherein v is the transfer rate of ultrasound wave in water.
Ultrasonic range finder is receiving the echoed signal s that reflects
2(t) time, also to receive a large amount of interference and noise signal.According to reflection equation, received signal to noise ratio S/N be inversely proportional to apart from 4 powers of d, promptly along with distance strengthens, S/N sharply descends.So the echoed signal that general ultrasonic range finder receives all has very big noise, even signal is buried by noise.Echoed signal S/N is low to be the principal element of restriction ultrasonic range finder combination property.In order to improve the combination property of ultrasonic range finder, people have proposed many improvement projects, develop the stadimeter of better performances, but the progress of not making a breakthrough property as yet so far, are always attending to one thing and lose sight of another aspect its integrated performance index improving, and the result is still undesirable.
A kind of design proposal of pulsed radar is disclosed as Jap.P. JP62-235587, this scheme is by adopting electronegative potential threshold level and two parallel detector circuits, can detect the moment that echo arrives as soon as possible on the one hand, the wrong moment value of thinking that echoed signal arrives of moment value that clutter can not arrived again simultaneously.This scheme reduced threshold level, improved the accuracy of range finding, but still has threshold level to exist, and can not accurately measure the real moment that echo arrives, and measuring error is still bigger, and is can detected target range also quite limited.
Jap.P. JP60-27875 provides a kind of dipulse ranging scheme, to closely with distant object the measurement appropriate signal of contrasting handle resolution characteristic when having improved close-in measurement and the detectivity when having strengthened telemeasurement.The defective of this scheme is that measuring error is bigger, and in receiving loop, through the signal after the envelope detection, its waveform rising front slows down, so be difficult to determine the accurate moment of echo arrival; Threshold level with certain potentials value is set in comparator circuit for this reason, is used to eliminate the clutter influence, but, must cut the part of signal waveform rising front, cause measuring error thus because threshold level exists.If the potential value of threshold level is too small, then clutter information can be thought by mistake be echoed signal, and cause bigger measuring error.
Patent CN1059498C provides a kind of method of pseudo-random supersonic ranging, this method is only to having the signal identification extraction of this time pseudorandom feature, thereby thoroughly eliminate the influence of environment clutter, be not subjected to the restriction of neighbourhood noise intensity, greatly improved antijamming capability.But the defective of this scheme is to receive and dispatch comparing one by one of the corresponding chip of pseudo-random code, expend the regular hour, particularly when the code length of pseudo-random code was very long, the time of cost was just longer, therefore this scheme does not have real-time, and realizes comparatively complicated.
Summary of the invention:
The object of the present invention is to provide a kind of " distance tracking loop " to realize the method and the ultrasonic range finder thereof of ultrasonic distance measuring under low signal-to-noise ratio, just use " distance tracking ring " to extract ultrasound wave self-emission transducer and be emitted to the needed journey time of measured target round trip, be the propagation delay time τ of picked up signal, thereby record the distance of measured target.
The fundamental measurement systematic schematic diagram is made of measured target 1 and the ultrasonic range finder 2 that is placed on the measuring point shown in Figure of description 1.The transmitting transducer 8 of ultrasonic range finder 2 is to measured target 1 emission one ultrasonic signal.The receiving transducer 9 of ultrasonic range finder 2 will receive the ultrasonic signal that measured target 1 reflects, and obtains video detection signal a after the amplification of ultrasonic signal process low noise, filtering and the detection that reflects.13 pairs of video detection signals of distance tracking ring a by ultrasonic range finder 2 does a series ofly to handle the estimated value that the back obtains the propagation delay time τ that reflected signal transmits relatively, thereby records the distance of measured target.
Ultrasonic ranging method of the present invention is to adopt distance tracking ring 13 to obtain the estimated value of the propagation delay time τ that reflected signal transmits relatively, and this has reflected major technique feature of the present invention, and the schematic diagram of distance tracking ring 13 is shown in Figure of description 2.The pulse signal baud generator 3 of ultrasonic range finder 2 is when producing transponder pulse signal s, and the recurrent pulse generator 29 of distance tracking ring 13 produces the input pulse P of a VCD (Control of Voltage time delay generator)
In, by input pulse P
In Trigger sawtooth generator 28 and produce a sawtooth voltage u (t), simultaneous input pulse P
InTrigger one of ripple gate pulse generator 30 generation sooner or later and open the pulse b of ripple door 21 early, pulse b produces the pulse c of a late ripple door 22 of unlatching through delayer 31.Under the control of pulse b and pulse c, ripple door 21 passes through late ripple door 22 through low-pass filter 24 integrations through low-pass filter 23 integrations with during pulse c to video detection signal a passing through early during the pulse b, obtains the integrated signal of two branch roads respectively.The integrated signal of these two branch roads subtracts each other in totalizer 25 after 26 filtering of F (s) loop filter, can obtain the error voltage e (t) of a corresponding propagation delay time τ.By the acting in conjunction of error voltage e (t) and sawtooth voltage u (t), will produce the output pulse P of a VCD at Control of Voltage time delay generator (VCD) 27
Out, the output pulse P of VCD so
OutInput pulse P with VCD
InBetween the time delay difference
, be the estimated value of the propagation delay time τ that reflected signal transmits relatively.
Description of drawings:
Fig. 1 is the fundamental measurement systematic schematic diagram.Among the figure, the 1st, measured target.The 2nd, ultrasonic range finder.The 3rd, the pulse signal baud generator.The 4th, frequency mixer.The 5th, local vibration source.6, the 11st, bandpass filter.The 7th, power amplifier.The 8th, transmitting transducer.The 9th, receiving transducer.The 10th, low noise amplifier.The 12nd, wave detector.The 13rd, the distance tracking ring.The 14th, range display.
Fig. 2 is the schematic diagram of distance tracking ring 13, has reflected major technique feature of the present invention.Among the figure, the 21st, ripple door early.The 22nd, late ripple door.23, the 24th, low-pass filter.The 25th, totalizer.The 26th, F (s) loop filter.The 27th, Control of Voltage time delay generator (VCD).The 28th, sawtooth generator.The 29th, the recurrent pulse generator.The 30th, morning and evening ripple gate pulse generator.The 31st, delayer.
Fig. 3 is the oscillogram of corresponding each point in the distance tracking ring 13.Among the figure, s is the transponder pulse signal waveform.A is the video detection signal waveform of reflection.B is for opening the pulse waveform of ripple door 21 early.C is for opening the pulse waveform of late ripple door 22.T
1Width for transponder pulse signal s.T
2Be the repetition period of transponder pulse signal s.τ is a propagation delay time.
Fig. 4 is the schematic diagram of Control of Voltage time delay generator (VCD) 27.Among the figure, P
InInput pulse for VCD.E (t) is control voltage.U (t) is a reference voltage.Pout is the output pulse of VCD.
Be the propagation delay time estimated value.
Implement metering system:
The concrete enforcement of fundamental measurement system is as follows.At radiating portion, pulse signal baud generator 3 produces one-period single pulse signal s, and (pulse width is T
1, the pulse repetition time is T
2, shown in Figure of description 3), produce local oscillation signal mixing in frequency mixer 4 with local vibration source 5, obtain modulation signal.Modulation signal is ultrasonic signal by transmitting transducer 8 with electrical signal conversion after bandpass filter 6 filtering and power amplifier 7 amplifications, to measured target 1 emission.Measured target 1 returns the ultrasonic reflections of incident to ultrasonic range finder 2.At receiving unit, the ultrasonic signal that measured target reflects receives through receiving transducer 9, the ultrasonic signal that receives is converted to electric signal, after low noise amplifier 10 is done low noise amplification, bandpass filter 11 filtering, obtains video detection signal a do envelope detection at wave detector 12.This video detection signal a is input to the estimation that distance tracking ring 13 is made propagation delay time τ, by estimating to obtain the time delay difference
Through conversion obtain measured target apart from d, on range display 14, show measurement result.
Because the estimation of 13 couples of propagation delay time τ of distance tracking ring is a major technique feature of the present invention, the realization principle and the specific implementation process of distance tracking ring 13 are as follows:
1. when the pulse signal baud generator 3 of ultrasonic range finder 2 was producing transponder pulse signal s, the recurrent pulse generator 29 of distance tracking ring 13 produced the input pulse P of a VCD
In, by the input pulse P of VCD
In Trigger sawtooth generator 28 and produce a sawtooth voltage u (t).Input pulse P
InWith sawtooth voltage u (t) shown in Figure of description 4.
2. the while is by the input pulse P of VCD
InTrigger one of ripple gate pulse generator 30 generation sooner or later and open the pulse b of ripple door 21 early, pulse b postpones T through delayer 31
1/ 2 backs produce a pulse c who opens late ripple door 22.Pulse b left margin is aimed at the input pulse P of VCD
In(also promptly aim at and send out the starting point that signal is penetrated in pulse).
3. ought receive the ultrasonic signal of a reflection, through a series of processing of fundamental measurement system receiving unit, the video detection signal a that obtains is input to distance tracking ring 13, and the relative transponder pulse signal of the video detection signal a s of this reflection has a time-delay τ.The waveform of transponder pulse signal s, pulse b, pulse c and video detection signal a is shown in Figure of description 3.
4. ripple door 21 passes through late ripple door 22 through low-pass filter 24 integrations through low-pass filter 23 integrations with during pulse c to this video detection signal a passing through early during the pulse b, can obtain the two-way integrated signal respectively, and by morning ripple door branch road integral energy be less than integral energy by late ripple door branch road.
5. the integrated signal of these two branch roads subtracts each other in totalizer 25, pass through 26 filtering of F (s) loop filter again after, just export the error voltage e (t) of a corresponding propagation delay time τ.Propagation delay time τ is big more, and error voltage e (t) is just big more.
6. this error voltage e (t) inputs to VCD Control of Voltage time delay generator 27 as control voltage, the sawtooth voltage u (t) that saw-toothed wave generator 28 produces also offers 27 conducts of VCD Control of Voltage time delay generator with reference to voltage, during as sawtooth voltage u (t) in case greater than control voltage e (t), VCD Control of Voltage time delay generator 27 will be exported the output pulse Pout of a VCD immediately.Time delay difference between the input pulse Pin of the output pulse Pout of VCD and VCD so
, be the estimated value of the propagation delay time τ that reflected signal transmits relatively.The schematic diagram of voltage control delay generator (VCD) is shown in Figure of description 4.
During concrete enforcement, should satisfy following relation:
If 1. the ultimate range between ultrasonic range finder 2 and the measured target 1 is d
Max, then pairing maximum transmitted time delay is τ
Max
2. the pulse width of the periodic single pulse signal s of pulse signal baud generator 3 generations is T
1, the pulse repetition time is T
2In order to improve distance accuracy and not have range ambiguity, should satisfy T
2T
1, T
1〉=2 τ
Max
3. as propagation delay time τ=τ
MaxThe time, error voltage e this moment (t) is just maximum, is set at V
Max
4. the maximum voltage value of setting the sawtooth voltage u (t) of saw-toothed wave generator 28 generations is V
Max, the value of u (t) is from the V that is raised to above freezing
MaxThe needed time is τ
Max
Compare with prior art, the present invention is used in to find range under the bad weather environment such as water, sleet and dense fog has following outstanding advantage:
1. for ambient noise, pass through late ripple door 22 by energy and the ambient noise of ripple door 21 morning behind low pass filter 23 integrations Energy behind low pass filter 24 integrations about equally, this two-way noise energy is almost nil after subtracting each other in adder 25, Can not impact error voltage e (t), can eliminate ambient noise so adopt apart from tracking loop, even signal is submerged in ring Also can effectively signal extraction be come out in the noise of border, therefore can realize telemeasurement and greatly improve anti-interference energy Power. And prior art arranges threshold level and stops noise, and threshold level has also been blocked far away when blocking noise The weak echo signal of distance, thereby limited widely the detectivity of ultrasonic range finder.
2. adopt distance-finding method of the present invention not need the real moment of determining that echo arrives, improved the accuracy of measuring. And existing skill Art becomes very mild because of the forward position of echo-signal waveform, and can't determine exactly the real moment that echo arrives, and measures Error is bigger.
3. not very big multipath signal for those Multipath Transmission time delays, adopt apart from tracking loop can reduce it to certainty of measurement yet Impact, therefore measuring system of the present invention has the ability that certain anti-multipath disturbs.
4. realize that simply operand is little.
Therefore, the detectivity of ultrasonic range finder of the present invention, antijamming capability, resolution characteristic, comprehensive technical performance indexs such as degree of accuracy all are to maximize.Ultrasonic range finder of the present invention be particularly suitable under water with inclement weather environment such as sleet, dense fog in range observation under the low signal-to-noise ratio.
Claims (2)
1. an employing " distance tracking loop " realizes the method for ultrasonic distance measuring under low signal-to-noise ratio, it is characterized in that adopting following steps:
The pulse signal baud generator (3) of A, ultrasonic range finder (2) is when producing transponder pulse signal s, and the recurrent pulse generator (9) of distance tracking ring (13) produces the input pulse P of a Control of Voltage time delay generator (VCD)
In, by the input pulse P of VCD
InTrigger sawtooth generator (28) and produce a sawtooth voltage u (t);
B, simultaneously by the input pulse P of VCD
InTrigger one of ripple gate pulse generator (30) generation sooner or later and open the pulse b of ripple door (21) early, pulse b postpones T through delayer (31)
1/ 2 backs produce a pulse c who opens late ripple door (22), and pulse b left margin is aimed at the input pulse P of VCD
In(also promptly aim at and send out the starting point that signal is penetrated in pulse);
C, when the ultrasonic signal of receiving a reflection, a series of processing through fundamental measurement system receiving unit, the video detection signal a that obtains is input to distance tracking ring (13), and the relative transponder pulse signal of the video detection signal a s of this reflection has a time-delay τ;
D, under the control of pulse b and pulse c, video detection signal a is passing through late ripple door (22) through low-pass filter (24) integration by ripple door morning (21) through low-pass filter (23) integration with during pulse c during the pulse b, obtain the two-way integrated signal respectively, and by morning ripple door branch road integral energy be less than integral energy by late ripple door branch road;
The integrated signal of E, these two branch roads subtracts each other in totalizer (25), pass through F (s) loop filter (26) filtering again after, just export the error voltage e (t) of a corresponding propagation delay time τ, propagation delay time τ is big more, error voltage is just big more;
F, this error voltage e (t) input to VCD Control of Voltage time delay generator (27) as control voltage, the sawtooth voltage u (t) that saw-toothed wave generator (28) produces also offers VCD Control of Voltage time delay generator (27) conduct with reference to voltage, during as sawtooth voltage u (t) in case greater than control voltage e (t), VCD Control of Voltage time delay generator (27) will be exported the output pulse Pout of a VCD, the time delay difference between the input pulse Pin of the output pulse Pout of VCD and VCD so immediately
, be the estimated value of the propagation delay time τ that reflected signal transmits relatively;
G, by the estimated value of propagation delay time τ
Obtain the distance of measured target through conversion.
2. ultrasonic range finder of implementing the described method of claim 1, comprise pulse signal wave launcher (3), frequency mixer (4), local vibration source (5), bandpass filter (6), (11), power amplifier (7), transmitting transducer (8), receiving transducer (9), low noise amplifier (10), wave detector (12), distance tracking ring (13), range display (14).
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| CN102096064B (en) * | 2010-11-12 | 2013-10-30 | 嘉兴中科声学科技有限公司 | Method and system used for accurately measuring time delay difference in short base line underwater acoustic positioning system |
| CN102889968B (en) * | 2012-10-12 | 2015-05-13 | 河海大学常州校区 | Acoustical method for detecting low-concentration sulfur hexafluoride gas |
| CN105187133B (en) * | 2015-09-30 | 2017-10-13 | 常州机电职业技术学院 | A kind of adaptive subsurface communication method of carrier frequency and its device |
| CN106771845B (en) * | 2015-11-19 | 2021-03-30 | 中兴通讯股份有限公司 | Method and device for determining distance between first reflection point and radio frequency unit |
| TWI646344B (en) * | 2018-03-19 | 2019-01-01 | 廣達電腦股份有限公司 | Electronic device, ultrasonic distance measuring device and method |
| CN108680909B (en) * | 2018-03-23 | 2021-06-04 | 海华电子企业(中国)有限公司 | Device and method for realizing performance monitoring of wave-measuring radar |
| CN109444898B (en) * | 2018-09-13 | 2020-09-04 | 中国船舶重工集团公司第七一五研究所 | Active sonar single-frequency tracking method |
| CN109520613B (en) * | 2018-11-29 | 2020-12-01 | 安徽江淮汽车集团股份有限公司 | Method for detecting bombing sound in pure electric van-type commercial vehicle |
| CN113390490A (en) * | 2021-07-26 | 2021-09-14 | 广州中工水务信息科技有限公司 | Inspection well water level measuring method, system and storage medium |
| CN114167424B (en) * | 2022-02-10 | 2022-05-17 | 北京星天科技有限公司 | Sound wave distance measuring method, device and system |
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| 低噪声回波测距系统的电路设计与系统分析. 陈先中，王伟，张争，程素森.北京科技大学学报，第27卷第4期. 2005 |
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