【正文】 Resistance: ≤ 450。s Law, data collection devices for data acquisition frequency must be greater than twice the highest frequency vibration signal, the signal can not occur until the frequency aliasing phenomenon, the need to design a lowpass filter for vibration signal through, filter out some highfrequency interference . The simplest lowpass filter formed by capacitors and resistors, shown in Figure, A simple RC lowpass circuit, the general call it passive lowpass filter.The lowpass filter Figure 43 shows the RC lowpass filter circuit, the voltage loop equation: Its gain The availability of the actual gain of Gain value is a function of frequency in the low frequency area Minimal， Signal pass。IC op amp is posed of highgain analog electronic devices, due to low prices, bined flexible and widely used. Analog signals can be proportional, integral, differential, and addition and subtraction and other operations. Figure 44 shows, LM324AD for Operational Amplifier chips, with the R22, and C4 position amplifier circuit, the circuit set the capacitor C4 is the role of negative feedback: RFCF is not large, lowfrequency signals will be fiction, virtually played the role of highpass filter, which with the previous RC lowpass filter needed to band together fiction outside the highfrequency noise signal and lowfrequency shaking signals at the same time by adjusting the value of C4,Get a different gain.In addition, R6, R15, R10, R22 four resistors form by the bipolar input op amp to convert a univocal input, in order to meet the requirements of ADchip unspooled input, input range can be +5 V ~ 5V. To adapt to most of the voltage sensor output characteristics. VM intervention voltage source, R93 access CH1 current source, can be adapted to current sensor, R85 and R14 for the protection of resistance. Unit Design and Implementation of ADC1．Select analogdigital conversion of basic technical indicators（1）Conversion time and the maximum sampling frequency ofSampling frequency chosen is too high will increase the amount of data and lead to followup analysis and processing workload increased dramatically. According to sampling theorem, the sampling frequency as long as the signal processing is greater than twice the highest frequency, we can not lose the information contained in the original signal. In practical work, generally selected, so that can determine the sampling interval, the analogdigital conversion modules, must be pleted within the sampling interval T conversion. Therefore, conversion time and the maximum sampling frequency of these two indicators is very important.（2）Conversion bitSelect the number of bits in the ADC, it is necessary according to its measurement range and accuracy required to determine the median conversion. The practical application of some of ADC, its end figures are not reliable, need to give up, so that measurement accuracy is reduced by half, this should be the choice when the ADC to be fully considered. Also, be sure to enable measurement of the signal through the opamp circuit, its voltage amplitude at the ADC within the scope of work.（3）Sample ChannelADC sampling channel is also able to input analog signals into large ones. In selecting analogdigital conversionDevice, we should take this into account, that is, parallel input channels simultaneously, or the order of the serial input.2．ADC cell design（1）ADC chip selectBased on the above choice of analogdigital conversion of basic technical indicators, data acquisition system used as the ADS8361 chip ADC module, ADS8361 is the production of It’s ADS8361 is a dualchannel, fourway, analog differential input, 16bit A / D conversion precision device。 ADS8361 The CS pin is the chip select terminal, Ml,M0, A0 pin used to select the sample channel and data channel。 SPI synchronous asynchronous serial port, master mode / slave mode.④ clock sources: external highprecision crystal / clock, the internal R / C oscillator。s central controller to control data acquisition from the SCM Uh2 and various I / O port for munication between and, through the USB interface Uh2 collected from the microcontroller to the data upload to the PC, for processing and analysis。振動分析的理論和狀態(tài)監(jiān)測技術(shù)是不可分割的有機(jī)體。機(jī)械和設(shè)備。振動傳感器的選擇必須考慮傳感器的性能要求。旋轉(zhuǎn)機(jī)械振動信號輸出正弦信號，使傳感器的動態(tài)特性，用來表示頻率響應(yīng)。壓電式加速度傳感器的質(zhì)量小，易于安裝在機(jī)械設(shè)備。?1kHz時，沒有特殊的前置放大器，安裝使用方便。 其工作原理：VS系列振動監(jiān)測速度傳感器是利用磁感應(yīng)原理的振動信號轉(zhuǎn)換成電信號。然后，配合二次儀表，這表明，振動速度或位移大小量。 177。 10 176。 一般分為低通濾波器，高通，帶通和帶阻濾波器，其頻率響應(yīng)特性如圖42所示。帶阻性能和帶通濾波器是相反的特定頻段信號的范圍內(nèi)，也就是說，被阻止，在通帶外的信號。低通濾波器圖43顯示了RC低通濾波電路，電壓回路方程： 其增益的實際收益的可用性 增益值的頻率在低頻面積最小，信號傳遞功能。③高輸入阻抗，低輸出阻抗④低漂移，低噪聲。圖44顯示，LM324AD與R22和C4組成的放大電路，運算放大器芯片，電路設(shè)置電容C4是負(fù)反饋的作用：RFCF并不大，低頻信號將小說，幾乎扮演高通濾波器的作用，這需要聯(lián)合起來小說以外的高頻噪聲信號和低頻震動信號，同時通過調(diào)整C4的值與以前的RC低通濾波器，獲得不同的增益。 ADC的單元設(shè)計與實現(xiàn)1 .選擇模擬 數(shù)字轉(zhuǎn)換的基本技術(shù)指標(biāo)（1）轉(zhuǎn)換時間和最高采樣頻率 采樣頻率選擇過高會增加的數(shù)據(jù)量，并導(dǎo)致后續(xù)分析和處理的工作量大大