【正文】 ple and practical four mon cathode LED digital tubes, with 74HC244 driver code segment, bit code with the PNP transistor 8550 drives. Ultrasonic transmitter Transmitter mainly by the 555 timer, 74LS123 monostable trigger circuit formed, enlarged links, and ultrasonic emission transducer T form, LM555 Multivibrator Port 3 output 145kHz square wave signal all the way through trigger circuit, amplifier circuitultrasonic transducer is sent to both ends, can increase the emission intensity adding the output coupling capacitor C4, launching drives to increase resistor R6 on the one hand can increase the output capacity of the amplification transistor, on the other hand can increase the ultrasonic transducer damping effect, shorten the time of its free oscillations.Piezoelectric ultrasonic transducers is the use of piezoelectric crystal resonance to the internal structure of ultrasonic transducers are introduced below, it has two chips, and a piezoelectric transducer it39。 the other hand, if the two electrodesno applied voltage, when the board receives the ultrasonic resonance, it will be pressure for piezoelectric vibration, the mechanical energy is converted to electrical signals, then it bees an ultrasonic receiver emission transducer and receiver transducer is slightly different in structure, use the device on the signs should be to distinguish between T and R. Ultrasonic detection receiving circuit Piezoelectric ultrasonic transducer S will receive the ultrasonic signals into electrical signals, and by R7, R8, R9, C5, C6, and 1 / 4 LM324 amplifier circuit posed of frequency selective amplification, the submission wave circuits Dl, C7, R10 Enveloping, vortex signal signal in the hysteresis voltage parator and RC rate than plastic filter circuit posed of the input links of the reference voltage 1/2Vcc parison with the wind speed is proportional to the plastic rectangular wave signal period varies with the detection signal. Ultrasonic wind speed measuring instrument software design mainly by the main program, ultrasonic receiving procedures and display, keyboard subroutine, temperature pensation know the assembly language program is a high efficient and easy to run precise calculation of the time, and ultrasonic velocity measurement instrument procedures require precise calculations (per unit time to plete the ultrasonic plastic rectangle when the number of square wave), the control programMixed programming using assembly language. Ultrasonic Range Finder Algorithm Ultrasonic wind sensor is the use of ultrasound through the air by the vortex modulation, has been transferred from the vortex frequency waves were detected to determine wind , S is a pair of the same resonant frequency ultrasonic transducer, F for the launching transducer, emission 145 kHz ultrasonic amplitude。 a vortex, because of the pressure gradient within the vortex and the vortex rotation, leading to ultrasonic refraction, reflection and absorption effects, so that the received signal through the beam, the received signal is back to , the ultrasonic frequency and amplitude changes in the frequency of vortex line, from the receiving transducer to detect changes in frequency ultrasonic beam amplitude can be measured wind speed values.Basic formula is:f = St * v / d f vortex frequency, Hz。 d bluff body diameter, mm。(2) The output itself is a linear relationship between wind velocity and pulse frequency signals, no zero drift, and the sensor sensitivity change would not directly affect output, high accuracy。 Karman vortex street。 temperature pensation目錄綜述...........................................................................................................................................ISummary...................................................................................................................................IV第1章 緒論.............................................................................................................................1 .......................................................................................1 課題的背景意義...........................................................................................1 課題的任務(wù)...................................................................................................1 國內(nèi)外超聲波風(fēng)速儀的現(xiàn)狀..................................................................................1 國外風(fēng)速儀的現(xiàn)狀.......................................................................................1 國內(nèi)測距儀的現(xiàn)狀.......................................................................................2 超聲波風(fēng)速儀的研究內(nèi)容......................................................................................3第2章 超聲波風(fēng)速儀測量原理及其總體設(shè)計.....................................................................4 超聲波風(fēng)速儀原理..................................................................................................4 風(fēng)速測量原理...............................................................................................4 超聲波風(fēng)速測量的理論分析.......................................................................5 超聲波傳感器工作原理..........................................................................................6 超聲波傳感器基本結(jié)構(gòu)及工作原理...........................................................6 超聲波傳感器的基本特性...........................................................................7 超聲波測距的總體設(shè)計..........................................................................................9 ................................................................................................9 ........................................................................................................10第3章 系統(tǒng)結(jié)構(gòu)及其硬件設(shè)計.............................................................................................11 單片機系統(tǒng)及復(fù)位電路設(shè)計........