毕业设计论文 外文文献翻译 超声波测距 中英文对照

汽车学院毕业设计科技文献翻译《Ultrasonic ranging system design》《超声测距系统设计》姓名刘涛涛专业电气工程及其自动化学号************班级2009级04班指导教师王红梅2013年 4月Ultrasonic ranging system designPublication title: Sensor Review. Bradford: 1993. Vol. 13 ABSTRACT：Ultrasonic ranging technology has wide using worth in many fields，such as the industrial locale，vehicle navigation and sonar engineering．Now it has been used in level measurement，self-guided autonomous vehicles, fieldwork robots automotive navigation，air and underwater target detection，identification，location and so on．So there is an important practicing meaning to learn the ranging theory and ways deeply. To improve the precision of the ultrasonic ranging system in hand，satisfy the request of the engineering personnel for the ranging precision，the bound and the usage，a portable ultrasonic ranging system based on the single chip processor was developed．Keywords：Ultrasound r，Ranging System，Single Chip Processor1.IntroductiveWith the development of science and technology, the improvement of people's standard of living, speeding up the development and construction of the city. urban drainage system have greatly developed their situation is constantly improving. However, due to historical reasons many unpredictable factors in the synthesis of her time, the city drainage system. In particular drainage system often lags behind urban construction. Therefore, there are often good building excavation has been building facilities to upgrade the drainage system phenomenon. It brought to the city sewage, and it is clear to the city sewage and drainage culvert in the sewage treatment system. comfort is very important to people's lives. Mobile robots designed to clear the drainage culvert and the automatic control system Free sewage culvert clear guarantee robot, the robot is designed to clear the culvert sewage to the core. Control System is the core component of the development of ultrasonic range finder. Therefore, it is very important to design a good ultrasonic range finder.2. A principle of ultrasonic distance measurement2.1 The principle of piezoelectric ultrasonic generatorPiezoelectric ultrasonic generator is the use of piezoelectric crystal resonators to work. Ultrasonic generator, the internal structure as shown, it has two piezoelectric chip and a resonance plate. When it's two plus pulse signal, the frequency equal to the intrinsic piezoelectric oscillation frequency chip, the chip will happen piezoelectric resonance, and promote the development of plate vibration resonance, ultrasound is generated. Conversely, if the two are not inter-electrode voltage, when the board received ultrasonic resonance, it will be for vibration suppression of piezoelectric chip, the mechanical energy is converted to electrical signals, then it becomes the ultrasonic receiver.The traditional way to determine the moment of the echo's arrival is based on thresholding the received signal with a fixed reference. The threshold is chosen well above the noise level, whereas the moment of arrival of an echo is defined as the first moment the echo signal surpasses that threshold. The intensity of an echo reflecting from an object strongly depends on the object's nature, size and distance from the sensor. Further, the time interval from the echo's starting point to the moment when it surpasses the threshold changes with the intensity of the echo. As a consequence, a considerable error may occur Even two echoes with different intensities arriving exactly at the same time will surpass the threshold at different moments. The stronger one will surpass the threshold earlier than the weaker, so it will be considered as belonging to a nearer object.2.2The principle of ultrasonic distance measurementUltrasonic transmitter in a direction to launch ultrasound, in the moment to launch the beginning of time at the same time, the spread of ultrasound in the air, obstacles on his way to return immediately, the ultrasonic reflected wave received by the receiver immediately stop the clock. Ultrasound in the air as the propagation velocity of 340m / s, according to the timer records the time t, we can calculate the distance between the launch distance barrier (s), that is: s = 340t / 23.Ultrasonic Ranging System for the Second Circuit DesignSystem is characterized by single-chip microcomputer to control the use of ultrasonic transmitter and ultrasonic receiver since the launch from time to time, single-chip selection of 8751, economic-to-use, and the chip has 4K of ROM, to facilitate programming. Circuit schematic diagram shown in Figure 2.Figure 1 circuit principle diagram3.1 40 kHz ultrasonic pulse generated with the launchRanging system using the ultrasonic sensor of piezoelectric ceramic sensors UCM40, its operating voltage of the pulse signal is 40kHz, which by the single-chip implementation of the following procedures to generate.puzel: mov 14h, # 12h; ultrasonic firing continued 200mshere: cpl p1.0; output 40kHz square wavenop;nop;nop;djnz 14h, here;retRanging in front of single-chip termination circuit P1.0 input port, single chip implementation of the above procedure, the P1.0 port in a 40kHz pulse output signal, after amplification transistor T, the drive to launch the first ultrasonic UCM40T, issued 40kHz ultrasonic pulse, and the continued launch of 200ms. Ranging the right and the left side of the circuit, respectively, then input port P1.1 and P1.2, the working principle and circuit in front of the same location.3.2 Reception and processing of ultrasonicUsed to receive the first launch of the first pair UCM40R, the ultrasonic pulse modulation signal into an alternating voltage, the op-amp amplification IC1A and after polarization IC1B to IC2. IC2 is locked loop with audio decoder chip LM567, internal voltage-controlled oscillator center frequency of f0 = 1/1.1R8C3, capacitor C4 determine their target bandwidth. R8-conditioning in the launch of the carrier frequency on the LM567 input signal is greater than 25mV, the output from the high jump 8 feet into a low-level, as interrupt request signals to the single-chip processing.Ranging in front of single-chip termination circuit output port INT0 interrupt the highest priority, right or left location of the output circuit with output gate IC3A access INT1 port single-chip, while single-chip P1.3 and P1. 4 received input IC3A, interruptedby the process to identify the source of inquiry to deal with, interrupt priority level for the first left right after. Part of the source code is as follows:receive1: push pswpush accclr ex1; related external interrupt 1jnb p1.1, right; P1.1 pin to 0, ranging from right to interrupt service routine circuitjnb p1.2, left; P1.2 pin to 0, to the left ranging circuit interrupt service routinereturn: SETB EX1; open external interrupt 1pop accpop pswretiright: ...; right location entrance circuit interrupt service routineAjmp Returnleft: ...; left Ranging entrance circuit interrupt service routineAjmp Return3.3 The calculation of ultrasonic propagation timeWhen you start firing at the same time start the single-chip circuitry within the timer T0, the use of timer counting function records the time and the launch of ultrasonic reflected wave received time. When you receive the ultrasonic reflected wave, the receiver circuit outputs a negative jump in the end of INT0 or INT1 interrupt request generates a signal, single-chip microcomputer in response to external interrupt request, the implementation of the external interrupt service subroutine, read the time difference, calculating the distance . Some of its source code is as follows:RECEIVE0: PUSH PSWPUSH ACCCLR EX0; related external interrupt 0MOV R7, TH0; read the time valueMOV R6, TL0CLR CMOV A, R6SUBB A, # 0BBH; calculate the time differenceMOV 31H, A; storage resultsMOV A, R7SUBB A, # 3CHMOV 30H, ASETB EX0; open external interrupt 0POP ACCPOP PSWRETIFor a flat target, a distance measurement consists of two phases: a coarse measurement and. a fine measurement:Step 1: Transmission of one pulse train to produce a simple ultrasonic wave.Step 2: Changing the gain of both echo amplifiers according to equation , until the echo is detected.Step 3: Detection of the amplitudes and zero-crossing times of both echoes.Step 4: Setting the gains of both echo amplifiers to normalize the output at, say 3 volts.Setting the period of the next pulses according to the : period of echoes. Setting the time window according to the data of step 2.Step 5: Sending two pulse trains to produce an interfered wave. Testing the zero-crossing times and amplitudes of the echoes. If phase inversion occurs in the echo, determine to otherwise calculate to by interpolation using the amplitudes near the trough. Derive t sub m1 and t sub m2 .Step 6: Calculation of the distance y using equation .4. The ultrasonic ranging system software designSoftware is divided into two parts, the main program and interrupt service routine. Completion of the work of the main program is initialized, each sequence of ultrasonic transmitting and receiving control.Interrupt service routines from time to time to complete three of the rotation direction of ultrasonic launch, the main external interrupt service subroutine to read the value of completion time, distance calculation, the results of the output and so on.5. ConclusionsRequired measuring range of 30cm ~ 200cm objects inside the plane to do a number of measurements found that the maximum error is 0.5cm, and good reproducibility. Single-chip design can be seen on the ultrasonic ranging system has a hardware structure is simple, reliable, small features such as measurement error. Therefore, it can be used not only for mobile robot can be used in other detection systems.Thoughts: As for why the receiver do not have the transistor amplifier circuit, because the magnification well, integrated amplifier, but also with automatic gain control level, magnification to 76dB, the center frequency is 38k to 40k, is exactly resonant ultrasonic sensors frequencyREFERENCES1. Fox, J.D., Khuri-Yakub, B.T. and Kino, G.S., "High Frequency Acoustic Wave Measurement in Air", in Proceedings of IEEE 1983 Ultrasonic Symposium, October 31-2 November, 1983, Atlanta, GA, pp. 581-4.2. Martin Abreu, J.M., Ceres, R. and Freire, T., "Ultrasonic Ranging: Envelope Analysis Gives Improved Accuracy", Sensor Review, Vol. 12 No. 1, 1992, pp. 17-21.3. Parrilla, M., Anaya, J.J. and Fritsch, C., "Digital Signal Processing Techniques for High Accuracy Ultrasonic Range Measurements", IEEE Transactions: Instrumentation and Measurement, Vol. 40 No. 4, August 1991, pp. 759-63.4. Canali, C., Cicco, G.D., Mortem, B., Prudenziati, M., and Taron, A., "A Temperature Compensated Ultrasonic Sensor Operating in Air for Distance and Proximity Measurement", IEEE Transaction on Industry Electronics, Vol. IE-29 No. 4, 1982, pp. 336-41.5. Martin, J.M., Ceres, R., Calderon, L and Freire, T., "Ultrasonic Ranging Gets ThermalCorrection", Sensor Review, Vol. 9 No. 3, 1989, pp. 153-5.超声测距系统设计原文出处：传感器文摘布拉福德:1993年第13页摘要：超声测距技术在工业现场、车辆导航、水声工程等领域都具有广泛的应用价值，目前已应用于物位测量、机器人自动导航以及空气中与水下的目标探测、识别、定位等场合。

毕业设计(论文)外文资料翻译系（院）：电子与电气工程学院专业：电气工程及其自动化姓名：学号：外文出处：United States Patent 5442592(用外文写)附件： 1.外文资料翻译译文；2.外文原文。

指导教师评语：签名：（手写签名）年月日注：请将该封面与附件装订成册。

外文资料翻译译文超声波测距仪文件类型和数目：美国专利5442592摘要：提出了一种可以抵消温度的影响和湿度的变化的新型超声波测距仪，包括测量单元和参考资料。

在每一个单位，重复的一系列脉冲的产生，每有一个重复率，直接关系到各自之间的距离，发射机和接收机。

该脉冲序列提供给各自的计数器，计数器的产出的比率，是用来确定被测量的距离。

出版日期：1995年8月15日主审查员：罗保.伊恩j.一、背景发明本发明涉及到仪器的测量距离，最主要的是，这种仪器，其中两点之间传输超声波。

精密机床必须校准。

在过去，这已经利用机械设备来完成，如卡钳，微米尺等。

不过，使用这种装置并不利于本身的自动化技术发展。

据了解，两点之间的距离可以通过测量两点之间的行波传播时间的决定。

这样的一个波浪型是一种超声波，或声波。

当超声波在两点之间通过时，两点之间的距离可以由波的速度乘以测量得到的在分离的两点中波中转的时间。

因此，本发明提供仪器利用超声波来精确测量两点之间的距离对象。

当任意两点之间的介质是空气时，声音的速度取决于温度和空气的相对湿度。

因此，它是进一步的研究对象，本次的发明，提供的是独立于温度和湿度的变化的新型仪器。

二、综述发明这项距离测量仪器发明是根据上述的一些条件和额外的一些基础原则完成的，其中包括一个参考单位和测量单位。

参考和测量单位是相同的，每个包括一个超声波发射机和一个接收机。

间隔发射器和接收器的参考值是一个固定的参考距离，而间距之间的发射机和接收机的测量单位是有最小距离来衡量的。

在每一个单位，发射器和接收器耦合的一个反馈回路，它会导致发射器产生超声脉冲，这是由接收器和接收到一个电脉冲然后被反馈到发射机转换，从而使重复系列脉冲的结果。

超声波清洗机论文中英文对照资料外文翻译文献中英文对照资料外文翻译文献超声波清洗超声波清洗是工业领域一种广泛应用的新方法，可以去除工件表面的磨削，研磨，抛光后表面残留的碎屑，去除工件表面残留的油污，甚至可以去除油漆层。

超声波清洗能够应用于从大到小的工业零件，大到波音747 飞机的引擎大修，小到手表的部件制作，都有超声波清洗的用武之地，目前广泛应用超声波清洗的行业涉及电子，精密机械，照明工程，光学，冶金，医疗仪器设备等诸多领域。

超声波清洗对工业的推动和影响是显而易见的，要真正理解超声波的价值，我们需要进一步了解超声波的原理。

超声波清洗原理超声波清洗的作用主要是一种叫做“空化效应”的现象造成的，每分钟数以十亿计的空泡向内爆裂，撞击到工件的表面，将工件表面的附着物剥离，分散开来。

对于一些手工清洗难以达到的位置，（例如深孔，死角等）超声波清洗也可以有很好的清洗效果，这也是超声波清洗的一个优点。

超声波清洗常用频率在 20 千赫到 50 千赫之间，常用清洗温度在50 -80 ℃ 之间。

在一个超声波清洗系统中,空化效应是由于一系列超声波换能器把声波导入清洗槽中的清洗液而产生。

这个声波传遍整个清洗槽, 在液体中产生了波的压缩和扩张。

在压缩波时，清洗液中的分子被紧密的压缩在一起，相反，在扩张波时，分子被快速的拉开了。

扩张是那么戏剧性，以至于分子被裂开了，形成了精微的气泡。

气泡里是局部真空的。

当气泡周围的压力变大时，周围的液体就涌过来，并使气泡爆裂。

当这个发生时，就产生了液体的喷射，导致温度高达 9032华氏度 (约为太阳的温度)。

这个极高的温度，伴随着液体喷射的速度，产生了一个非常强烈的清洗作用。

然而，因为气泡的扩张和爆裂周期是那么短暂，伴随在气泡外的液体迅速吸收了热量，从而在清洗过程中防止了清洗槽和清洗液过热。

影响清洗效果的因素有 7 个主要影响清洗效果的原因:1.清洗时间2.清洗液温度3.采用的清洗液4.工件的外形设计5.超声波频率6.超声功率密度7.清洗装夹方式清洗时间是影响超声波清洗效果的一个主要因素，清洗时间取决于工件的污染程度以及清洁度要求，典型的清洗时间是 2-10 分钟，只有少数工件能够在很短的时间里面清洗干净。

附录A 英文原文ULTASONIC RANGING IN AIRG. E. Rudashevski and A. A. GorbatovOne of the most important problems in instrumentation technology is the remote,contactless measurement of distances in the order of 0.2 to 10 m in air.Such a problem occurs,for instance,when measuring the relativethre edimensional position of separate machine members or structural units.Interesting possibilities for its solution are opened up by utilizing ultrasonic vibrations as an information carrier.The physical properties of air,in which the measurements are made,permit vibrations to be employed at frequencies up to 500 kHz for distances up to 0.5 m between a member and the transducer,or up to 60 kHz when ranging on obstacles located at distances up to 10 m.The problem of measuring distances in air is somewhat different from other problems in the a -pplication of ultrasound.Although the possibility of using acoustic ranging for this purpose has been known for a long time,and at first glance appears very simple,nevertheless at the present time there are only a small number of developments using this method that are suitable for practical purposes.The main difficulty here is in providing a reliable acoustic three-dimensional contact with the test object during severe changes in the air's characteristic.Practically all acoustic arrangements presently known for checking distances use a method of measuring the propagation time for certain information samples from the radiator to the reflecting member and back.The unmodulated acoustic(ultrasonic)vibrations radiated by a transducer are not in themselves a source of information.In order to transmit some informational communication that can then be selected at the receiving end after reflection from the test member,the radiated vibrations must be modulated.In this case the ultrasonic vibrations are the carrier of the information which lies in the modulation signal,i.e.,they are the means for establishing the spatial contact between the measuring instrument and the object being measured.This conclusion,however,does not mean that the analysis and selection of parameters for the carrier vibrations is of minor importance.On the contrary,the frequency of the carrier vibrations is linked in a very close manner with the coding method for the informational communication,with the passband of the receiving and radiating elements in the apparatus,with the spatial characteristics of the ultrasonic communication channel,and with the measuring accuracy.Let us dwell on the questions of general importance for ultrasonic ranging in air,namely:on the choice ofa carrier frequency and the amount of acoustic power received.An analysis shows that with conical directivity diagrams for the radiator and receiver,and assuming thatthe distance between radiator and receiver is substantially smaller than the distance to the obstacle,theamount of acoustic power arriving at the receiving area Pr for the case of reflection from an ideal planesurface located at right angles to the acoustic axis of the transducer comes towhere Prad is the amount of acoustic power radiated,B is the absorption coefficient for a plane wave inthe medium,L is the distance between the electroacoustic transducer and the test me -mber,d is the diameterof the radiator(receiver),assuming they are equal,and c~is the angle of the directivity diagram for theelectroacoustic transducer in the radiator.Both in Eq.(1)and below,the absorption coefficient is dependent on the amplitude and not on theintensity as in some works[1],and therefore we think it necessary to stress this difference.In the various problems of sound ranging on the test members of machines and structures,therelationship between the signal attenuations due to the absorption of a planewave and due to thegeometrical properties of the sound beam are,as a rule,quite different.It must be pointed out that the choiceof the geometrical parameters for the beam in specific practical cases is dictated by the shape of thereflecting surface and its spatial distortion relative to some average position.Let us consider in more detail the relationship betweenthe geometric and the power parameters ofacoustic beams for the most common cases of ranging on plane and cylindrical structural members.It is well known that the directional characteristic W of a circular piston vibrating in an infinite baffle is afunction of the ratio of the piston's diameter to the wavelength d/λ as found from the following expression:(2)where Jl is a Bessel function of the first order and α is the angle between a normal to the piston and aline projected from the center of the piston to the point of observation(radiation).From Eq.(2)it is readily found that a t w o-t o-o n e reduction in the sensitivity of a radiator with respectto sound pressure will occur at the angle（3）For angles α≤20.Eq.(3)can be simplified to（4） where c is the velocity of sound in the medimaa and f is the frequency of the radiated vibrations.It follows from Eq.(4)that when radiating into air where c=330 m/s e c,the necessary diameter of the radiator for a spedfied angle of the directivity diagram at the 0.5 level of pressure taken with respect to the fdc 76.05.0≈αaxis can befound to be（5）where disincm,f is in kHz,and α is in degrees of angle.Curves are shown in Fig.1 plotted from Eq.(5)for six angles of a radiator's directivity diagram.The directivity diagrm needed for a radiator is dictated by the maximum distance to be measured and bythe spatial disposition of the test member relative to the other structural members.In order to avoid theincidence of signals reflected from adjacent members onto the acoustic receiver,it is necessary to provide asmall angle of divergence for the sound beam and,as far as possible,a small-diameter radiator.These tworequirements are mutually inconsistent since for a given radiation frequency a reduction of the beam'sdivergence angle requires an increased radiator diameter.In fact,the diameter of the"sonicated"spot is controlled by two variables,namely:the diameter of theradiator and the divergence angle of the sound beam.In the general case the minimum diameter ofthe"sonicated"spot Dmin on a plane surface normally disposed to the radiator's axis is given by（6）where L is the least distance to the test surface. The specified value of Dmin corresponds to a radiator with a diameter（7）As seen from Eqs.(,6)and(7),the minimum diameter of the"sonieated"spot at the maximum requireddistancecannot be less than two radiator diameters.Naturally,with shorter distances to the obstacle the sizeof the"sonicated" surface is less.Let us consider the case of sound ranging on a cylindrically shaped object of radius R.The problem is to measure the distance from the electroacoustic transducer to the side surface of the cylinderwith its various possible displacements along the X and Y axes.The necessary angleαof the radiator'sdirectivity diagram is given in this case by the expression（8） whereα is the value of the angle for the directivity diagram,Ymax is the maximum displacement of the cylinder's center from the acoustic axis,and Lmin is the minimum distance from the center of theelectroacoustic transducer to the reflecting surface measured along the straight line connecting the center ofthe m e m b e r with the center of the transducer.It is clear that when measuring distance,the"running"time of the information signal is controlled by thefd α1400≈fcL d 5.1=fcLD 6min =min maxarcsinL R y +≥αlength of the path in a direction normal to the cylinder's surface,or in other words,the measure distance isalways the shortest one.This statement is correct for all cases of specular reflection of the vibrations from thetest surface.The simultaneous solution of Eqs.(2)and(8)when W=0.5 leads to the following expression:(9) In the particular case where the sound ranging takes place in air having c=330 m/sec,and on theasstunption that L min <<R,the necessary d i a m e t e r of a unidirectional piston radiator d can be found fromthe fomula (10) where d is in cm and f is in kHz. Curves are shown in Fig.2 for determining the necessary diameter of the radiator as a function of theratio of the cylinder's radius to the maximum displacement from the axis for four radiation frequencies.Alsoshown in this figure is the directivity diagram angle as a function of R and Y rnax for four ratios of m i n i m u mdistance to radius.The ultrasonic absorption in air is the second factor in determining the resolution of ultrasonic rangingdevices and their range of action.The results of physical investigations concerning the measurement ofultrasonic vibrations air are given in[1-3].Up until now there has been no unambiguous explanation of thediscrepancy between the theoretical and expe -rimental absorption results for ultrasonic vibrations inair.Thus,for frequencies in the order of 50 to 60 kHz at a temperature of+25oC and a relative humidity of37%the energy absorption coefficient for a plane wave is about 2.5dB/m while the theoretical value is 0.3 dB/m.The absorption coefficient B as a function of frequency for a temperature of+25o Cand a humidity of37%according to the data in[2]can be described by Table 1.The absorption coefficient depends on the relative humidity.Thus,for frequencies in the order of 10 to20kHz the highest value of the absorption coefficient occurs at 20%humidity[3],and at 40%humidity theabsorption is reduced by about two to one.For frequencies in the order of 60 kHz the maximum absorptionoccurs at 30.7o humidity,dropping when it is increased to 98% or lowered to 10%by a factor of approximatelyfour to one.The air temperature also has an appreciable effect on the ultrasonic absorption[1].When thetemperature of the medium is increased from+10 to+30,the absorption for frequencies between 30 and 50kHz increases by about three to one.Taking all the factors noted above into account we arrive at the following approximate values for theabsorption coefficient:at a frequency of 60 kHz /3min =0.15 m -1 and~max=0.5-1;at a frequency of 200 ()maxmin 76.0y L R d +=λmax25fy R d ≈kHz/~min=0.6 m -1 and B max =2 m -1.（11）The values for the minimum~min and rnaxil-num~max"transmittance"coefficients were obtained in thea bsence of aerosols and rain.Their difference is the result of the possible variations in temperature over therange from -3 0 to+50~and in relative hmnidity over the range from 10 to 98%.The overall value ofthe"transmittance"is obtained by multiplying the values of g and 0 for given values of L,f,and d.L I T E R A T U R E C I T E DMoscow(1957).Moscow(1960).附录B 中文翻译在空气中超声测距G. E. Rudashevski and A. A. Gorbatov在仪器技术中远程是最重要的一个问题。

International Journal of Computer science & Information Technology (IJCSIT), Vol 1, No 2, November 2009EFFECT OF VARIATION OF SEPARATION BETWEEN THE ULTRASONIC TRANSMITTER AND RECEIVER ON THE ACCURACY OF DISTANCE MEASUREMENTAjay Kumar Shrivastava1, Ashish Verma2 and S. P. Singh31Department of Computer Application, Krishna Institute of Engineering and Technology, Ghaziabad (U.P.), Indiaajay@2Department of Physics and Electronics, Dr H S Gour University, Sagar (M.P.), Indiavermaashish31@3Department of Electronics and Communication, Noida Institute of Engineering and Technology, Ghaziabad (U.P.), Indiasahdeopsingh@ABSTRACTAccuracy of distance measurement of an object from an observation point such as a stationary or moving vehicle, equipment or person is most important in large number of present day applications. Ultrasonic sensors are most commonly used due to its simplicity and low cost. The accuracy of the measured distance is dependent on the separation between the ultrasonic transmitter and receiver. This dependency has been studied and reported in this paper. The result shows that the accuracy of distance measured is dependent on the separation between the transmitter and the receiver.KEYWORDSAccuracy of distance measurement, Ultrasonic sensor, distance measurement, microcontroller, sewer pipeline inspection, sewer pipeline maintenance, robotics.1. INTRODUCTIONDistance measurement of an object in front or by the side of a moving or stationary entity is required in a large number of devices and gadgets. These devices may be small or large and also quite simple or complicated. Distance measurement systems for such applications are available. These use various kinds of sensors and systems. Low cost and accuracy as well as speed are important in most of the applications. Hence ultrasonic sensors are most commonly used. To maintain the accuracy of measured distance the separation between transmitter and receiver is very important. In this paper, we describe the results of a study on the variation of error of measurement of distance of an object by varying the separation between the transmitter and receiver of the ultrasonic sensors by using microcontroller P89C51RD2. Ultrasound sensors are very versatile in distance measurement. They are also providing the cheapest solutions. Ultrasound waves are suitable both for air and underwater use [1].19International Journal of Computer science & Information Technology (IJCSIT), Vol 1, No 2, November 2009Ultrasonic sensors are also quite fast for most of the common applications. In simpler system a low cost version of 8- bit microcontroller can be used to implement the system to lower the cost. We are applying this system for sewer inspection system. Sewer blockages have become quite common. The blockages have become more frequent due to the dumping of polythene bags, hair and solid materials into the sewer system [2], [3]. There has been no work done in this direction. This is a new study which is useful to find out the optimal separation between ultrasonic transmitter and receiver to measure small distances.2. PRINCIPLEUltrasonic transducer uses the physical characteristics and various other effects of ultrasound of a specific frequency. It may transmit or receive the ultrasonic signal of a particular strength. These are available in piezoelectric or electromagnetic versions. The piezoelectric type is generally preferred due to its lower cost and simplicity to use [5]. The transmitter and receiver are available either as single unit or as separate units. The Ultrasonic wave propagation velocity in the air is approximately 340 m/s, the same as sonic velocity. To be precise, the ultrasound velocity is governed by the medium, and the velocity in the air is calculated using the formula given below (1). V= 340+0.6(t-15) m/s t:temperature, °C (1)In this study, we assumed the temperature to be 20°C, so the velocity of ultrasound in the air is 343 m/s. Because the travel distance is very short, the travel time is little affected by temperature. It takes approximately 29.15µsec for the ultrasound to propagate through 1cm, so it is possible to have 1cm resolution in the system [6].3. EXPERIMENTAL SETUPThe system consists of a transmitter and a receiver module controlled by a microcontroller P89C51RD2. We have used a microcontroller development kit for testing of the system. We are using 40Khz ultrasound sensors for our experiments. The Simplified block diagram of the system is shown in Fig.1. In Fig. 1, the interrupt1 signal initiates the system. When the interrupt1 signal is generated, MCU starts the timer1 to measure time and simultaneously generates the controlled 40Khz pulses having a train of specific number of pulses. These pulses are applied to the amplifier circuit and after amplification the ultrasound transmitter transmits the pulse train in the direction of the object. These ultrasonic pulses are reflected from the object and travels back in different directions. These reflected waves arrive at receiver. After amplification and processing it generates signal interrupt. This is applied as interrupt2 to the MCU. Interrupt2 stops the timer1, and MCU calculates the time elapsed between the generation of the wave and reception of the wave. This time is proportional to the distance travelled by the waves. Using the formula, MCU calculates the distance of the obstacle and display it or transfer it to the part of the total system where it is used for further control. Using this elapsed time, we calculate the distance of the object from the ultrasonic sensors.20International Journal of Computer science & Information Technology (IJCSIT), Vol 1, No 2, November 2009INT1 MCU Ultrasound Transmitter CircuitTINT2 Receiver Amplifier Display RFig 1: Block Diagram of the System4. EXPERIMENTAL RESULTSThe waveforms of the transmitted and received waveforms of the ultrasonic signal is stored in Digital Storage Oscilloscope. We have taken the readings for various separation between tranmitter and reciever. We have measured the distance in the interval of 5cm. For every measured distance three reading have been taken. The table shows the average of the three readings. The maesured distance is calculated on the basis of travelled time. The formula to calculate the distance is given below: Dist. (cm) = (Travelled Time*10-6 * 34300) / 2 (2)The ultrasonic waves travelled from the transmitter to the object and from the object back to the receiver hence the whole distance is divided by two. Values of %Error have also been calculated and shown. The error result shows that there is some error in recording the start and finish times in the system. When the distance increases the error is distributed in a larger distance and hence the %error decreases. We have taken the measurements for various separations of transmitter and receiver renging from 2cm to 15cm. The Table 1 shows the results when separation between tranmitter and reciever is 2cm. Table 1: Experimental Results (For 2cm Separation between Transmitter and Reciever) S.No . 1 2 3 4 5 6 7 8 9 10 Actual Distance(cm) 5 10 15 20 25 30 35 40 45 50 Travelled Time (µSec) 400 690 1050 1250 1650 1930 2180 2400 2700 3000 Measured Distance (cm) 6.86 11.83 18.01 21.44 28.30 33.10 37.39 41.16 46.31 51.45 % Error 37.20 18.34 20.05 7.19 13.19 10.33 6.82 2.90 2.90 2.90The result shows that the acuracy of measured distance is increses for longer distances. The %error becomes constant for measured distances above 40cm. The highest %error is occured in small distance of 5cm. It is also shown by Fig.2.21International Journal of Computer science & Information Technology (IJCSIT), Vol 1, No 2, November 2009Fig. 2: Graph of Actual Distance versus Measured Distance for 2cm Separation between Transmitter and Reciever. The Table 2 shows the result when separation between transmitter a reciever is 5cm. Table 2: Experimental Results for 5cm Separation between Transmitter and reciever) S.No. 1 2 3 4 5 6 7 8 9 10 Actual Distance(cm) 5 10 15 20 25 30 35 40 45 50 Travelled Time (µSec) 410 700 1000 1300 1600 1870 2220 2500 2780 3120 Measured Distance (cm) 7.03 12.01 17.15 22.30 27.44 32.07 38.07 42.88 47.68 53.51 % Error 40.63 20.05 14.33 11.48 9.76 6.90 8.78 7.19 5.95 7.02The resluts shows that the accuracy is incresed in camparison to the previous results. This is also shown by the Fig. 3.Fig. 3: Graph of Actual Distance versus Measured Distance when Separation between Transmitter and Reciever is 5 cm.22International Journal of Computer science & Information Technology (IJCSIT), Vol 1, No 2, November 2009The Table 3 shows the results when separation between transmitter and reciever is 10 cm. These results indicates that when we increase the separation between transmitter and receiver the %error increses for small measured distances. Table 3: Experimental Results for Separation of 10cm between Transmitter and reciever)S.No. 1 2 3 4 5 6 7 8 9 10Actual Distance(cm) 5 10 15 20 25 30 35 40 45 50Travelled Time (µSec) 620 750 1010 1310 1600 1870 2200 2400 2680 3000Measured Distance (cm) 10.63 12.86 17.32 22.47 27.44 32.07 37.73 41.16 45.96 51.45% Error 112.66 28.63 15.48 12.33 9.76 6.90 7.80 2.90 2.14 2.90Again the accuracy increases with the distance but the small distances are not so accurate. The error is high for small distances. It is also shown by the Fig. 4.Fig. 4: Graph of Actual Distance versus Measured Distance when Separation between Transmitter and Reciever is 10 cm. The Table 4 is showing the result of measured distance when 15cm separation between transmitter and reciever. These results shows that when we increase the separation between transmitter and receiver the %error increses. This increase is very high in small measured distances like 5cm in our experiment. The lowest %error observed for the measured distance of 45cm and again it is increasing for the measured distance of 50cm. The results shows that we have to stop the increament of seaparation between transmitter and receiver in our experiment.23International Journal of Computer science & Information Technology (IJCSIT), Vol 1, No 2, November 2009Table 4: Experimental Results for 15cm Separation between Transmitter and Reciever) S.No. 1 2 3 4 5 6 7 8 9 10 Actual Distance(cm) 5 10 15 20 25 30 35 40 45 50 Travelled Time (µSec) 1300 930 1180 1350 1620 1900 2200 2420 2700 3200 Measured Distance (cm) 22.30 15.95 20.24 23.15 27.78 32.59 37.73 41.50 46.31 54.88 % Error 345.90 59.50 34.91 15.76 11.13 8.62 7.80 3.76 2.90 9.76Again the error for the small distance say 5cm is very high. It is also showing that the graph between actual distance versus measured distance is not a straight line. This graph is shown in Fig. 5.Fig. 5: Graph of Actual Distance versus Measured Distance for 15cm Separation between Transmitter and Reciever. The graph between the measured distance the actual distance indicates that the measured distance is proportional to the actual distance.5. ANALYSIS OF THE RESULTSThe experimental results shows that the distance measured for different separations between transmitter and receiver are accurate for long distances e.g. more than 20cm. For small actual distances say 5cm, the small transmitter and receiver distances are better in comparison to the long distances between transmitter and receiver. If we place the transmitter and receiver at 15cm separation than the small distance like 5cm are not going to be measured correctly. Result shows the error of 345%. Hence we have to place the transmitter and receiver at proper distance like 5-10cm. For long distances the distance between transmitter and receiver has very low impact on the accuracy. We have compared the all measured distances for different separations between transmitter and receiver and the results are shown in the Table 5.24International Journal of Computer science & Information Technology (IJCSIT), Vol 1, No 2, November 2009Table 5: Comparison of Measured Distances for different Separations between Transmitter and Reciever Actual Dist. (cm) 5 10 15 20 25 30 35 40 45 50 Measured Distance (in cm) when Separation between Transmitter and Reciever is = 2cm 6.86 11.83 18.01 21.44 28.30 33.10 37.39 41.16 46.31 51.45 5cm 7.03 12.01 17.15 22.30 27.44 32.07 38.07 42.88 47.68 53.51 10cm 10.63 12.86 17.32 22.47 27.44 32.07 37.73 41.16 45.96 51.45 15cm 22.30 15.95 20.24 23.15 27.78 32.59 37.73 41.50 46.31 54.88S. No. 1 2 3 4 5 6 7 8 9 10As we can see in the table that small measured distance like 5cm is measured accurately when 2cm separation between transmitter and receiver. It has the lowest error. When we increase the distance to be measured, the accuracy of measured distance are high and it the highest for 10cm separation between transmitter and receiver. Hence for the range of 5cm to 50cm, as we taken in our experiments, the separation between transmitter and receiver are 2cm to 10cm. If we increase this than the error percentage also increases. The Fig.6 shows the graph between actual distance and the different measured distances for various separations between transmitter and receiver.Fig. 6: Graph for Comparison of Measured Distances for different Separations between Transmitter and Reciever This graph is also showing that the graph plotting of measured distance when separation between transmitter and receiver is 2cm, 5cm and 10cm is almost on the same points. The graph plotting when 15cm separation between transmitter and receiver, is not very encouraging for this range of 5cm to 50cm.25International Journal of Computer science & Information Technology (IJCSIT), Vol 1, No 2, November 20096. CONCLUSIONSWe have done the experiments on our ultrasonic measurement system for the various separations between transmitter and receiver and the result shows that the measured distance is satisfactory for our study. When the distance increases the error becomes constant and very less. A correction may be applied to calculate the correct distance. Interrupt1 initiates the system and interrupt2 stops the timer and on the basis of the travelled time distance calculated. In future, the whole system will be mounted on the one PCB. This study shows that for small distances the separation between transmitter and receiver should be 5cm to 10cm. Hence this study will help in fixing the separation between transmitter and receiver in the robotic vehicle for blockage detection so we are able to calculate the more accurate distance of the blockage in the sewage filled sewer lines. Hence we can prevent human labour to go in the sewage filled sewer lines to detect the blockage which are very dangerous to the human as they contain the poisonous gases.ACKNOWLEDGMENTThis work is supported by MP Council of Science and Technology (MPCST), Bhopal, Project Code No. R&D/PHYSICS.23/08-09-1.REFERENCES[1] J. David and N cheeke “Fundamentals of Ultrasonic Waves” CRC Press, Florida, USA, 2002, ISBN 0-8493-0130-0. [2] Singh SP, Verma Ashish, Shrivastava AK “Design and Development of Robotic Sewer Inspection Equipment Controlled by Embedded Systems” Proceedings of the First IEEE International Conference on Emerging Trends in Engineering and Technology, July 16-18, 2008, Nagpur, India pp. 1317-1320. [3] Shrivastava AK, Verma Ashish, Singh SP “Partial Automation of the Current Sewer Cleaning System”, Invertis Journal of Science and Technology, Vol.1, No.4, 2008, pp 261-265. [4] O. Duran, K.Althoefer, and L Seneviratene, “State of the Art in Sensor Technologies for Sewer Inspection”, IEEE Sensors Journal, April 2002, Vol. 2, N.2, pp 63. [5] Hongjiang He, Jianyi Liu, “The Design of Ultrasonic Distance Measurement System Based on S3C2410” Proceedings of the 2008 IEEE International Conference on Intelligent Computation Technology and Automation, 20-22 Oct, 2008, pp. 44-47. [6] Yongwon Jang, Seungchul Shin, Jeong Won Lee, and Seunghwan Kim, “A Preliminary Study for Portable Walking Distance Measurement System Using Ultrasoinc Sensors” Proceedings of the 29th Annual International Conference of the IEEE EMBS Cité Internationale Lyon, France, Aug 23-26, 2007, pp. 5290-5293.26International Journal of Computer science & Information Technology (IJCSIT), Vol 1, No 2, November 2009AuthorsAjay Kumar Shrivastava was born at Guna (M.P.), India on 7th August, 1977. He had done his graduation in Electronics from Dr. H.S.Gour University, Sagar (M.P.), India in 1998. After that he had completed his MCA from the same university in 2002. He has more than seven years of teaching experience. He had worked as Lecturer in Technocrats Institute of Technology, Bhopal (M.P.), India for three years. Presently he is working as Associate Professor in Krishna Institute of Engineering and Technology, Ghaziabad (U.P.), India from Aug. 2005. His research interests include Embedded Systems and Data Mining. Mr. Shrivastava is the life member of Computer Society of India (CSI). He is also life member of Association of Computer, Electronics and Electrical Engineers (ACEEE) and International Association of Computer Science and Information Technology (IACSIT) and International Association of Engineers (IAENG). He is also the member of Computer Science Teachers Association (CSTA). He is also reviewer of various ACEEE organized conferences. He has published a paper in National Journal and published/presented four papers in conferences.Dr. Ashish Verma was born on 23rd March 1963. He received the M.Sc. degree in Physics with specialization in Electronics and solidstate physics in1984 and Ph.D. degree in Physics in 1991 from Dr. Hari Singh Gour Central University, Sagar, (M.P.), India. He has having 24 years of teaching (UG/PG) and research experience and is currently working as a Senior Lecturer in the department of Physics and Electronics, Dr. Hari Singh Gour Central University, Sagar. He has guided about 150 students (UG/PG) for their projects in the field of Electronics and Physics. He guided 4 Ph.D. students (One as Co-Supervisor). Presently, he is guiding 8 Ph.D. students for their innovative research. He is supervising 3 Ph.D. students in Physics and Electronics of M.P. BHOJ (Open) University, Bhopal, (M.P.), India. He had published a book entitled “Microprocessor”, Vishwavidyalaya Prakashan, Sagar (M.P.), India and written two chapters in “Bhotiki”, Madhya Pradesh Hindi Granth Academy, Bhopal (M.P.), India. Dr. Verma published / presented about 50 research papers in the National /International Journals / Conferences of high repute. He is the Executive Council (Government Nominee) in Government Girls Autonomous College, Sagar, (M.P.). He had worked in various committees of the university. Prof. S.P.Singh was born at village Manirampur in Nalanda district, Bihar, India on 10th June 1939. He did his schooling and intermediate studies at Patna. He completed his B.Sc.(Engg.) degree in Electrical Engineering from National Institute of Technology, Jamshedpur, India in the year 1964. He did M.Tech. in Electrical Engineering (Electronic Devices and Circuits) from Indian Institute of Technology, Kanpur, India in 1975. He obtained his Ph.D. degree from Ranchi University, Ranchi, India in the year 1993. His topic was microprocessor based speed control of induction motors.27International Journal of Computer science & Information Technology (IJCSIT), Vol 1, No 2, November 2009He joined N.I.T., Jamshedpur, India as Lecturer in Electrical Engineering in 1964 continued there as lecturer, AP and Professor till 1999. He started teaching electronic subjects and shifted to electronics engineering. After retirement from NIT in 1999, he continued to work as professor in institutes around Delhi. Currently, he is working as professor in Electronics & Communication Engineering at Noida Institute of Engineering and Technology, Greater Noida, U.P., India. Prof. Singh was a member of IEEE from 1974 to 1991. At present Dr. Singh is a fellow of I.E.T.E., India.28。

=======大学本科生毕业设计外文文献及中文翻译文献题目： ULTRASONIC RANGING SYSTEM 文献出处： United States Patent译文题目：超声波测距系统学生：指导教师：专业班级：自动化11-4学号： 110601140416电气信息工程学院2014年5月1日超声波测距系统摘要超声波测距系统，是指选择性地激励一个变压器，使之产生换能器驱动信号。

超声换能器发射的超声波脉冲用于响应驱动信号然后接收到一个在超声波信号发出之后的回波信号。

分路开关接在变压器的绕组上，当超声波信号的传输在允许的近距离范围内达到一个稳定的等级，分路开关选择性的闭合来阻止蜂鸣器报警。

第1章发明背景像在宝丽来相机中应用的可用范围测试系统，它们都是准确而且可靠的，但都不适用于近距离测距，举个例子，2到3英寸的距离内就不适用，所以他们在9英寸甚至更远的距离测距是可靠的。

它们可以应用在很多的应用程序中，但不适用于可移动机器人领域内。

机器人通常必须通过门口只有两三英寸的间隙，如果当可移动机器人被操作于避障模式下通过狭小空间，可能机器人的规避路径过于狭窄，此外,规避动作应该使偏指定的路径距离最小化。

近距离测距不用于超声波系统的一个原因是，近距离输出脉冲输出太长以至于它重叠在回波脉冲上，即使输出脉冲缩短,输出脉冲仍然重叠回波脉冲，因为声音紧跟着输出脉冲。

备中产生的回波信号脉冲的范围为100毫伏，但设置传感器响应所必需的电路回声脉冲是大约150伏到300伏之间。

因此即使是最小的声波也会盖过回声信号。

事实上,dual-diode钳位电路用于将150伏降低到二极管的击穿电压，即0.7伏特。

但是这700毫伏足以盖过100毫伏的回波信号。

目前系统需要50毫秒将300伏特的峰值发射电压降到0.7伏特，且额外需要500到600毫秒的时间将它稳定在1毫伏范围。

第2章发明总结本发明可以提供一种改进的超声波测距系统。

本发明也可以提供一个改进的多通道超声波测距系统。

超声波测距摘要：本演示处理了测量距离的超声波传感器在当前环境中的准确性。

作为一个测量传感器的选择SFR08型配备了允许寻址的I ²C 通信接口。

这一事实使得创建传感器阵列变得简单。

控制和可视化系统是基于PC PC。

NI USB 8451是作为通信卡使用的。

验证测量的目标是确定实际的传感器精度，特别是当测量较长的距离。

当评估传感器的精度时，不包括在所测量的数据的温度补偿。

关键词：超声波传感器，I ²C 通信接口，虚拟仪器1 1 简介简介超声波传感器通常用于自动化的任务来测量距离，位置变化，电平测量，如存在检测器或在特殊应用中，例如，当测量透明材料的纯度。

它们是基于测量超声波的传播时间的原则。

这一原则确保可靠的检测是独立的颜色渲染的对象或其表面的设计和类型。

它可以可靠地检测甚至液体，散装材料，透明物体，玻璃等材料。

他们使用的另一个参数是他们在侵略性的环境中使用，不是非常敏感的污垢和测量距离的可能性。

超声波传感器在许多机械设计中被制造。

对于实验室用途，用于发射器和接收器单独或在一个单一的简单的住房，对于工业用途，往往建造坚固的金属外壳。

有些类型允许您使用电位计或数字来调整灵敏度。

此外，输出可以在统一的版本中或直接以数字形式的模拟信号直接中。

就传感器来说，可以通过通信接口连接到PC ，它是可以设置所有传感器的工作范围和测量距离的详细参数。

2 2 超声测量超声测量超声对环境中的声音具有相似的传播特性。

这是机械振动的粒子环境。

超声波可以在气体、液体和固体中传播。

对于超声波通常被认为是一个频率高于20千赫的声音。

千赫的声音。

根据超声波的用途可以分为两类： 主动超声：当应用表现出物理或化学效应。

生成的输出达到更高的值。

超声波用于清洁，焊接，钻孔等。

被动超声；输出是在低得多（通常是小）值产生的对比度。

他的主要应用领域是测量距离，检测材料的缺陷和材料的厚度，测量液体和气体的流量，以及医疗保健的诊断。

外文翻译毕业设计题目：超声波倒车雷达预警原文1：DISTANCE MEASURING AND MONITORING DEVICE EQUIPPED AUTOMOBILE REVERSE RADAR译文1：距离测量和监控设备装备汽车反向雷达原文2：ULTRASONIC SENSOR ASSEMBLY FOR AVEHICLE REVERSING RADAR译文2DISTANCE MEASURING AND MONITORING DEVICE EQUIPPED AUTOMOBILE REVERSE RADAR(原文1)This design relates to an automobile commutating radar, an ultrasonic sensor comprising the radar. The ordinary car commutation radar is usually installed in the rear bumper of a car. The vehicle has a commutation radar sensor, a ceramic chip in the polarization electric field, due to the reverse piezoelectric vibration of the aluminum housing and transmitting an ultrasonic signal, and receiving the reflected ultrasonic signal into an effective distance. Therefore, a driver will know that this situation is reversed in the rear of the vehicle do not have to stop looking for the front of the vehicle.A good ultrasonic sensor ultrasonic signal should be sent to a central area, produced a strong reaction in order to achieve a sensitive detection. The distance along the line of its axis with reference to Figure 5, a conventional ultrasonic sensor sensitive areas, the reception sensitivity in a test has 250 cm, and a sensitive, including 60 degree angle in the above 2 (X) cm. Thus, the conventional sensor performance has a low accuracyIn some vehicles, the most traditional ultrasonic sensor mounted in the front and rear bumpers. Vehicles of a monitor in a dashboard display, ultrasonic sensor detects an obstacle. However, with the conventional ultrasonic sensor has a sensitive wide angle, they must be installed in the end of the bumper to prevent the ultrasonic signals interfere with each other. However, the distance in each ultrasonic sensor is so large is still very low detection accuracy.In addition, when parking the vehicle, ultrasonic sensors often detect other vehicles parked next to the vehicle as an obstacle, so the driver may be a false alarm.Accordingly, the present design provides an improved ultrasonic sensors to reduce or eliminate the above problems.Summary of the designThe main purpose is to provide the design of an ultrasonic sensor sensitive to the radar has high precision long distance and a little sensitive to the angle of the car for. Other objectives, advantages and novel features of the design will become more apparent from the following detailed description together when an ultrasonic transducer assembly of the vehicle the commutation radar has an ultrasonic sensor and the two wires. A sleeve is received by the rubbermaterial and has a chamber sensor. A tapered opening that is defined in a front chamber. A wave guide cone is provided to open and close to the sensor in the center of the tapered. By using the sensor assembly, automotive radar there is a reversal of precision long detection distance in a concentrated area.The reference to the diagram, an ultrasonic sensor assembly for a car reversing radar, in accordance with the design consists of a sensor, a set, a guided wave cone, and a housing (ultrasonic sensor has a structure like traditional sensors, and two wires extending from sensors.Sleeve, usually made of rubber, there is one which is defined as the receiving sensor. A tapered shape of the opening is defined at the front and an opening formed on the lower side to prevent the ultrasonic signal reflected from the ground to cause false alarms. A flange formed on the rear of the sleeve.The definition channel for receiving signals. A rear cover is provided on the rear side of the space to encapsulate the sensor and the sleeve inside.In the assembled state shown in Figure 2, the guide wave cone installed you like bracket combination conical opening of the center of the casing and highlights. The heating wire extends the bracket backward and exit back cover. The sleeve is placed in the housing flange butt shoulder wires and heating wire extends from the back cover of the diaphragm. A pad, made of a resin or other soft material, is provided between the sleeve is An ci back cover, so the sleeve and the sensor housing can be stably received.Figure 4 illustrates a detector effect Contrast sensor and unguided wave cone, wherein the solid line illustrates the sensor wave guide cone, and the conflict lines described sensor without the guided wave taper. As shown in Figure 4, at a test frequency of about 40 kHz (35 kHz), gift of design of the sensor can be provided to an ultrasonic signal with a Federation higher than traditional sensors. Therefore, the design of detection better than traditional sensors作者：Joan Smith；Mike Howard ；国籍：USA出处：United States Patent距离测量和监控设备装备汽车反向雷达(译文1)本设计涉及一种汽车换向雷达,用一个超声波传感器组成该雷达。

附录附录A外文翻译the equivalent dc value. In the analysis of electronic circuits to be considered in a later course, both dc and ac sources of voltage will be applied to the same network. It will then be necessary to know or determine the dc (or average value) and ac components of the voltage or current in various parts of the system.EXAMPLE 13.13 Determine the average value of the waveforms of Fig. 13.37.FIG. 13.37Example 13.13.Solutions:a. By inspection, the area above the axis equals the area below over one cycle, resulting in an average value of zero volts.b. Using Eq.(13.26):as shown in Fig. 13.38.In reality, the waveform of Fig. 13.37(b) is simply the square wave of Fig. 13.37(a) with a dc shift of 4 V; that is v2 =v1 + 4 VEXAMPLE 13.14 Find the average values of the following waveforms over one full cycle:a.Fig. 13.39.b. Fig. 13.40.Solutions:We found the areas under the curves in the preceding example by using a simple geometric formula. If we should encounter a sine wave or any other unusual shape, however, we must find the area by some other means. We can obtain a good approximation of the area by attempting to reproduce the original wave shape using a number of small rectangles or other familiar shapes, the area of which we already know through simple geometric formulas. For example,the area of the positive (or negative) pulse of a sine wave is 2Am.Approximating this waveform by two triangles (Fig. 13.43), we obtain(using area1/2 base height for the area of a triangle) a rough idea of the actual area:A closer approximation might be a rectangle with two similar triangles(Fig. 13.44):which is certainly close to the actual area. If an infinite number of forms were used, an exact answer of 2Am could be obtained. For irregular waveforms, this method can be especially useful if data such as the average value are desired. The procedure of calculus that gives the exact solution 2Am is known as integration. Integration is presented here only to make the method recognizable to the reader; it is not necessary to be proficient in its use to continue with this text. It is a useful mathematical tool, however,and should be learned. Finding the area under the positive pulse of a sine wave using integration, we havewhere ∫ is the sign of integration, 0 and p are the limits of integration, Am sin a is the function to be integrated, and d a indicates that we are integrating with respect to a. Integrating, we obtainSince we know the area under the positive (or negative) pulse, we can easily determine the average value of the positive (or negative) region of a sine wave pulse by applying Eq. (13.26):For the waveform of Fig. 13.45,EXAMPLE 13.15 Determine the average value of the sinusoidal waveform of Fig.13.46.Solution: By inspection it is fairly obvious thatthe average value of a pure sinusoidal waveform over one full cycle iszero.EXAMPLE 13.16 Determine the average value of the waveform of Fig. 13.47.Solution: The peak-to-peak value of the sinusoidal function is16 mV +2 mV =18 mV. The peak amplitude of the sinusoidal waveform is, therefore, 18 mV/2 =9 mV. Counting down 9 mV from 2 mV(or 9 mV up from -16 mV) results in an average or dc level of -7 mV,as noted by the dashed line of Fig. 13.47.EXAMPLE 13.17 Determine the average value of the waveform of Fig. 13.48.Solution:EXAMPLE 13.18 For the waveform of Fig. 13.49, determine whether the average value is positive or negative, and determine its approximate value.Solution: From the appearance of the waveform, the average value is positive and in the vicinity of 2 mV. Occasionally, judgments of this type will have to be made. InstrumentationThe dc level or average value of any waveform can be found using a digital multimeter (DMM) or an oscilloscope. For purely dc circuits,simply set the DMM on dc, and read the voltage or current levels.Oscilloscopes are limited to voltage levels using the sequence of steps listed below:1. First choose GND from the DC-GND-AC option list associated with each vertical channel. The GND option blocks any signal to which the oscilloscope probe may be connected from entering the oscilloscope and responds with just a horizontal line. Set the resulting line in the middle of the vertical axis on the horizontal axis, as shown in Fig. 13.50(a).2. Apply the oscilloscope probe to the voltage to be measured (if not already connected), and switch to the DC option. If a dc voltage is present, the horizontal line will shift up or down, as demonstrated in Fig. 13.50(b). Multiplying the shift by the vertical sensitivity will result in the dc voltage. An upward shift is a positive voltage (higherpotential at the red or positive lead of the oscilloscope), while a downward shift is a negative voltage (lower potential at the red or positive lead of the oscilloscope). In general,1. Using the GND option, reset the horizontal line to the middle of the screen.2. Switch to AC (all dc components of the signal to which the probe is connected will be blocked from entering the oscilloscope—only the alternating, or changing, components will be displayed).Note the location of some definitive point on the waveform, such as the bottom of the half-wave rectified waveform of Fig. 13.51(a); that is, note its position on the vertical scale. For the future, whenever you use the AC option, keep in mind that the computer will distribute the waveform above and below the horizontal axis such that the average value is zero; that is, the area above the axis will equal the area below.3. Then switch to DC (to permit both the dc and the ac components of the waveform to enter the oscilloscope), and note the shift in the chosen level of part 2, as shown in Fig.13.51(b). Equation(13.29) can then be used to determine the dc or average value of the waveform. For the waveform of Fig. 13.51(b), the average value is aboutThe procedure outlined above can be applied to any alternating waveform such as the one in Fig. 13.49. In some cases the average value may require moving the starting position of the waveform under the AC option to a different region of the screen or choosing a higher voltage scale. DMMs can read the average or dc level of any waveform by simply choosing the appropriate scale.13.7 EFFECTIVE (rms) V ALUESThis section will begin to relate dc and ac quantities with respect to the power delivered to a load. It will help us determine the amplitude of a sinusoidal ac current required to deliver the same power as a particular dc current. The question frequently arises, How is it possible for a sinusoidal ac quantity to deliver a net power if, over a full cycle, the net current in any one direction is zero (average value 0)? It would almost appear that the power delivered during the positive portion of the sinusoidal waveform is withdrawn during the negative portion, and since the two are equal in magnitude, the net power delivered is zero. However, understand that irrespective of direction, current of any magnitude through a resistor will deliver power to that resistor. In other words, during the positive or negative portions of a sinusoidal ac current, power is being delivered at eachinstant of time to the resistor. The power delivered at each instant will, of course, vary with the magnitude of the sinusoidal ac current, but there will be a net flow during either the positive or the negative pulses with a net flow over the full cycle. The net power flow will equal twice that delivered by either the positive or the negative regions of sinusoidal quantity. A fixed relationship between ac and dc voltages and currents can be derived from the experimental setup shown in Fig. 13.52. A resistor in a water bath is connected by switches to a dc and an ac supply. If switch 1 is closed, a dc current I, determined by the resistance R and battery voltage E, will be established through the resistor R. The temperature reached by the water is determined by the dc power dissipated in the form of heat by the resistor.If switch 2 is closed and switch 1 left open, the ac current through the resistor will have a peak value of Im. The temperature reached by the water is now determined by the ac power dissipated in the form of heat by the resistor. The ac input is varied until the temperature is the same as that reached with the dc input. When this is accomplished, the average electrical power delivered to the resistor R by the ac source is the same as that delivered by the dc source. The power delivered by the ac supply at any instant of time isThe average power delivered by the ac source is just the first term, since the average value of a cosine wave is zero even though the wave may have twice the frequency of the original input current waveform. Equating the average power delivered by the ac generator to that delivered by the dc source,which, in words, states thatthe equivalent dc value of a sinusoidal current or voltage is 1/2or 0.707 of its maximum value.The equivalent dc value is called the effective value of the sinusoidal quantity.In summary,As a simple numerical example, it would require an ac current with a peak value of 2 (10) 14.14 A to deliver the same power to the resistor in Fig. 13.52 as a dc current of 10 A. The effective value of any quantity plotted as a function of time can be found by using the following equation derived from the experiment just described:which, in words, states that to find the effective value, the function i(t) must first be squared. After i(t) is squared, the area under the curve isfound by integration. It is then divided by T, the length of the cycle or the period of the waveform, to obtain the average or mean value of thesquared waveform. The final step is to take the square root of the meanvalue. This procedure gives us another designation for the effectivevalue, the root-mean-square (rms) value. In fact, since the rms term isthe most commonly used in the educational and industrial communities,it will used throughout this text. EXAMPLE 13.19 Find the rms values of the sinusoidal waveform in each part of Fig.13.53.Solution: For part (a), I rms 0.707(12 10 3 A) 8.484 mA.For part (b), again I rms 8.484 mA. Note that frequency did notchange the effective value in (b) above compared to (a). For part (c),V rms 0.707(169.73 V) 120 V, the same as available from a home outlet. EXAMPLE 13.20 The 120-V dc source of Fig. 13.54(a) delivers 3.6 W to the load. Determine the peak value of the applied voltage (Em) and the current (Im) if the ac source [Fig. 13.54(b)] is to deliver the same power to the load.Solution:EXAMPLE 13.21 Find the effective or rms value of the waveform of Fig. 13.55.Solution:EXAMPLE 13.22 Calculate the rms value of the voltage of Fig. 13.57.Solution:EXAMPLE 13.23 Determine the average and rms values of the square wave of Fig.13.59.Solution: By inspection, the average value is zero.The waveforms appearing in these examples are the same as thoseused in the examples on the average value. It might prove interesting tocompare the rms and average values of these waveforms.The rms values of sinusoidal quantities such as voltage or currentwill be represented by E and I. These symbols are the same as thoseused for dc voltages and currents. To avoid confusion, the peak valueof a waveform will always have a subscript m associated with it: Im sin q t. Caution: When finding the rms value of the positive pulse of asine wave, note that the squared area is not simply (2Am)2 4A2m; itmust be found by a completely new integration. This will always bethe case for any waveform that is not rectangular.A unique situation arises if a waveform has both a dc and an ac componentthat may be due to a source such as the one in Fig. 13.61. Thecombination appears frequently in the analysis of electronic networkswhere both dc and ac levels are present in the same system.The question arises, What is the rms value of the voltage vT? Onemight be tempted to simply assume that it is the sum of the rms valuesof each component of the waveform; that is, VT rms 0.7071(1.5 V) 6 V 1.06 V 6 V 7.06 V. However, the rms value is actuallydetermined bywhich for the above example is直流值相等。

H8/300L超声波测距仪（原文出处：第1页-第15页）介绍该应用说明介绍了一种使用H8/38024 SLP MCU的测距仪。

由单片机产生40KHz 方波，通过超声波传感器发射出去。

反射的超声波被另外一个传感器接收。

有效距离为6cm到200cm。

1.理论1.1概况在这篇应用说明中，H8/38024F微处理器是作为目标设备被使用的。

由于简单的可移植性，超声波测距仪使用的软件为C语言。

超声波是频率高于可听音的一切高于20kHz的声波。

用于医疗诊断和影像的超声波，频率延长和超过了10兆赫兹，高的频率有短的波长，这使得超声波从物体反射回来更容易。

不幸的是，极高的频率难以产生和测量。

对超声波的检测与测量主要是通过压电式接收机进行的。

超音波普遍应用于防盗系统、运动探测器和车载测距仪。

其他应用包括医疗诊断(人体成像)，清洁(去除油脂和污垢)，流量计(利用多普勒效应)，非破坏性试验(检测材料缺陷)，焊接等各个方面。

1.2软件实施距离的计算要测量超声波传感器接收到回波的时间。

理想的被测对象应该有一个大的面积而且不吸收超声波。

在这个应用说明中使用了38024f的CPU电路板。

图1展示超声波测距仪的工作原理，tmofh (脚63 )是用来传送0.5ms的40kHz的超声波，irq0 ( pin72 ) 是用来探测反射波的。

发送超声波后，计时器C开始追踪Timer Counter C (TCC)的计数数目，以计算物体的距离。

图1.测距仪工作原理1.2.1 发射超声波定时器F是一个具有内置式输出比较功能16位计数器，它还可以用来作为两个独立的8位定时器FH和FL，这里，定时器F是作为两个独立的8位定时器使用。

计时器的FL被初始化为产生中断，而FH在比较匹配发生时触发了tmofh的输出电平。

表1 计时器F的时钟选择对于为定时器的FL，选定内部时钟ø/32。

输出比较寄存器FL装载数据初值为H’FF 。

因此,外部定时器每1.67msec 产生一个中断，计算如下：/2ø晶振频率=，计时器FL 内部时钟周期=322⨯晶振频率=64MHz 8304.9=153.6kHz 中断周期=256kHz6.1531⨯=1.67msec 每隔65msec 开始发射一次超声波，计时器FL 须中断近39次( 65msec / 1.67msec = 39 )，才开始传送。