【正文】 shold 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. principle of ultrasonic distance measurement Ultrasonic 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 / 2 3 Ultrasonic Ranging System for the Second Circuit Design System is characterized by singlechip microputer to control the use of ultrasonic transmitter and ultrasonic receiver since the launch from time to time, singlechip selection of 8751, economictouse, and the chip has 4K of ROM, to facilitate programming. Circuit schematic diagram shown in Figure 2. Figure 1 circuit principle diagram 40 kHz ultrasonic pulse generated with the launch Ranging system using the ultrasonic sensor of piezoelectric ceramic sensors UCM40, its operating voltage of the pulse signal is 40kHz, which by the singlechip implementation of the following procedures to generate. puzel: mov 14h, 12h。 nop。 pin to 0, ranging from right to interrupt service routine circuit jnb , left。 left Ranging entrance circuit interrupt service routine Ajmp Return The calculation of ultrasonic propagation time When you start firing at the same time start the singlechip 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。 open external interrupt 1 pop acc pop psw reti right: ...。 ret Ranging in front of singlechip termination circuit input port, single chip implementation of the above procedure, the 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 and , the working principle and circuit in front of the same location. Reception and processing of ultrasonic Used to receive the first launch of the first pair UCM40R, the ultrasonic pulse modulation signal into an alternating voltage, the opamp amplification IC1A and after polarization IC1B to IC2. IC2 is locked loop with audio decoder chip LM567, internal voltagecontrolled oscillator center frequency of f0 = 1/, capacitor C4 determine their target bandwidth. R8conditioning 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 lowlevel, as interrupt request signals to the singlechip processing. Ranging in front of singlechip termination circuit output port INT0 interrupt the highest priority, right or left location of the output circuit with output gate IC3A access INT1 port singlechip, while singlechip and P1. 4 received input IC3A, interrupted by 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 psw push acc clr ex1。 output 40kHz square wave nop。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 object39。 還有許許多多給予我學(xué)業(yè)上鼓勵和幫助的朋友，在此無法一一列舉，在此也一并表示忠心地感謝！ 參考文獻(xiàn) [1] 李勇 .《車載單片機(jī)與車載網(wǎng)絡(luò)技術(shù)》 .第一版 .電子工業(yè)出版社 ， 2022 年： P57 [2] 王懿川 .《 基于單片機(jī)控制的超聲波測距報警系統(tǒng)》 .上海計量測試 ， 2022 年第 5期： P45~P47 [3] 陳明計 .《單片機(jī)應(yīng)用設(shè)計基礎(chǔ)》 .第一版 .北京 航空航天大學(xué)出版社 ， 2022 年：P89~P90 [4] 胡佳文 .《 51 系列單片機(jī)原理及設(shè)計實(shí)例》 .北京航空航天大學(xué)出版社， 2022 年：P79 [5] 周潤景 .《單片機(jī)設(shè)計分析與制作》 .機(jī)械工業(yè)出版社 ， 2022 年： P123~P124 [6] 陳濤 .《單片機(jī)應(yīng)用及 C51 程序設(shè)計》 .第二版 . 機(jī)械工業(yè)出版社 ， 2022 年：P93 [7] 龔運(yùn)新 .《單片機(jī)接口 C 語言開發(fā)技術(shù)》 .第一版 .清華大學(xué)出版社 ， 2022 年：P234~P235 附錄 A 英文文獻(xiàn) Ultrasonic ranging system design Publication 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， selfguided 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 Processor 1 Introductive With the development of science and technology, the improvement of people39。在我畢業(yè)論文寫作期間，各位老師給我提供了種種專業(yè)知識上的指導(dǎo)和日常生活上的關(guān)懷，沒有您們這樣的幫助和關(guān)懷，我不會這么順利的完成畢業(yè)設(shè)計，借此機(jī)會向您們表示由衷的感激。測量距離較近，測量距離較大時，顯示的數(shù)據(jù)就會有較大的誤差。 （