【正文】 號(hào)的分析判斷結(jié)果；另一方面需要轉(zhuǎn)換成其他信息才能用于分析判斷，因此在進(jìn)行數(shù)據(jù)分析判斷之前要對(duì)信號(hào)進(jìn)行相應(yīng)的處理。信號(hào)處理指從傳感器得來的信號(hào)進(jìn)行變換、放大、濾波、調(diào)制/解調(diào)、模/ 數(shù)和數(shù)/模轉(zhuǎn)換、識(shí)別、估值等加工處理，以便削弱信號(hào)中多余、無用分量并增強(qiáng)信號(hào)中有用分量，或?qū)⑿盘?hào)變換成某種更希望的形式，提取需要的特征值，從而全面、準(zhǔn)確地獲取有用信息。在本系統(tǒng)中，信號(hào)狐貍主要是對(duì)信號(hào)進(jìn)行信號(hào)消噪。從傳感器得來的信號(hào)往往很微弱，并常?；煊性肼?。如果這些噪聲處于有用信號(hào)之外，則可以用模擬濾波器予以消除。如果噪聲是與信號(hào)頻譜交疊的弱信號(hào)，可以考慮用取樣積分等方法來提取有用信息。信號(hào)處理的根本目的是提高信噪比。 信號(hào)傳輸與通信信號(hào)傳輸與通信主要完成測(cè)試系統(tǒng)裝置間或測(cè)試裝置與其他環(huán)節(jié)間的信息傳輸。在這里主要是測(cè)試裝置與計(jì)算機(jī)之間的傳輸、網(wǎng)絡(luò)傳輸。在本測(cè)試系統(tǒng)中，虛擬儀器中硬件采用 PCI 卡式虛擬儀器，用來獲取處理后的信號(hào)。PCI （peripheral ponent interconnect）外部設(shè)備互連總線，是一種即插即用的總線標(biāo)準(zhǔn)，采用地址/ 數(shù)據(jù)總線復(fù)用方式，最高總線時(shí)鐘可達(dá) 66 MHz，最高峰值傳輸速度可達(dá) 528 MHz。PC 上的 PCI總線以 33 MHz 的時(shí)鐘頻率操作，采用 32 位數(shù)據(jù)總線，數(shù)據(jù)傳輸速度可達(dá)132MB/S，PCI 總線是一種自動(dòng)配置的總線，即居于完整的即插即用（ plug amp。 play）功能。 數(shù)據(jù)分析與判斷和數(shù)據(jù)顯示在此檢測(cè)系統(tǒng)中，運(yùn)用美國(guó) NI 公司研制開發(fā)的虛擬儀器軟件 LabVIEW 來實(shí)現(xiàn)對(duì)信號(hào)數(shù)據(jù)的處理和分析以及最后的數(shù)據(jù)顯示。具體處理方法見第六章。結(jié)論通過以上的介紹和分析，可得到以下結(jié)論：（1）通過基波相位分離法可以有效的消除直流分量和諧波分量的影響，得到基波分量的幅值和相位信息。（2）非同步采樣補(bǔ)償算法很好的解決了基波相位分離法對(duì)于被測(cè)信號(hào)必須是采樣信號(hào)周期的整數(shù)倍的苛刻要求，在增加較少運(yùn)算量的同時(shí)提高的測(cè)量精度。（3）利用 NI 公司開發(fā)的虛擬儀器平臺(tái) LabVIEW 可以實(shí)現(xiàn)這個(gè)算法，不僅提高了儀器的智能化程度和測(cè)試性能，還方便操作，具有良好的推廣價(jià)值。致 謝本次畢業(yè)設(shè)計(jì)是在胡廣振老師悉心的指導(dǎo)下完成的。胡廣振老師首先從基本能力訓(xùn)練入手，培養(yǎng)我自我學(xué)習(xí)的能力，循循善誘使我在整個(gè)設(shè)計(jì)的過程中始終做到有的放矢。在此，衷心的感謝胡老師在進(jìn)行畢業(yè)論文工作中所給予的幫助。同時(shí)，也感謝我親愛的同學(xué)對(duì)我的無私幫助和大力支持，使我在論文工作中得以順利進(jìn)行。最后，謹(jǐn)向所有幫助過我的老師、同學(xué)和朋友，向全部引文的作者表以深深的謝意。參考文獻(xiàn)[1]王昌長(zhǎng)，李福棋，[M].北京：清華大學(xué)出版社，2022：46. [2]屠志健，[M].北京：中國(guó)電力出版社 2022：1114 .[3]葉逢春，[J].西北電力技術(shù)，2022，18(1) ：811.[4] and MEASUREMENT OF DIELECRIC CONTANT AND LOSS ANGLE OVERA CONTINUOUS PREQUENCY RANGE[J].Izvestiya (5):1520.[5][J]. ，24(2) ：1217. [6]白格平，[J].洛陽師專學(xué)報(bào)，1999，18(2)： 2935.[7]馬為民，[J].清華大學(xué)學(xué)報(bào)（自然科學(xué)版） ，1997，37(1)： 1217.[8]陳楷，胡志堅(jiān)，王卉，[J].電網(wǎng)技術(shù)，2022，28(18) ：5861.[9]王瑞明，董連文，[J].高壓電器，2022，39(3) 4244.[10][J].儀器儀表用戶，2022,10(4)： 2122.[11][J].山東師范大學(xué)學(xué)報(bào)（自然科學(xué)版） ，2022，21(2)： 137138.[12]高育芳，[J].檢驗(yàn)檢測(cè)，2022，5(1) ：3537.[13]鐘凡亮， 平臺(tái)下的測(cè)試軟件系統(tǒng)設(shè)計(jì)與實(shí)現(xiàn)[J ]. 計(jì)算機(jī)與數(shù)字工程，2022，35(1) ：138140.[14]侯躍謙，李慧，[J].長(zhǎng)春大學(xué)學(xué)報(bào)，2022，16(4)： 2931.AUTOMATIC MEASUREMENT OF DIELECTRIC CONSTANT AND LOSS ANGLEOVER A CONTINUOUS FREQUENCY RANGEM. A. Akhmamet39。ev and S. M. KazakovIzvestiya VUZ. Fizika, Vol. 10, No. 5, pp. 1520, 1967Automatic measurement of and is measured from audio to radio frequencies with a ?tanx?transformer bridge. Parasitic frequency errors are eliminated by modulation, the control signal being provided by the envelope. A mathematical description of the sensitivity is given. The block diagram of the plete bridge is given, together with test results for the range 50 Hz to 200 kHz. There is often a need for automatic measurement of the parameters of impedances over wide frequency ranges, as in testing materials for e and tan 6 in radiation physics over the range 50 Hz to 200 kHz. A bridge method is the best, but it may be difficult to use from lack of standards of low resistance suitable for use over a wide frequency range, and also because it is difficult to provide a small constant phase shift in wideband amplifiers for automatic balancing. There are two main ways of overing these difficulties:1) A reactance standard (capacitor) is used instead of the resistance standard, this being fed with current 90 ~ out of phase with the bridge current. However, this requires the use of frequencydependent phase shifters to maintain the 90 ~ shift, and these are very difficult to produce for wide continuous ranges, so the method is used only at fixed frequencies.2) The bridge is balanced with respect to one ponent only, the other ponent being deduced from the residual outofbalance voltage. This provides the basis for continuous operation in manual [24] and automatic bridges. The main disadvantage of such automatic bridges is that the quadrature detectors, which provide the control signals, have to work at the bridge frequency。 then the frequencydependent phase shifts in the wideband amplifier give rise to an additional error, which is rather difficult to correct. This difficulty may be overe if the arm voltages are modulated at a frequency well below the working frequency, the control signals being formulated from the envelope of the outofbalance voltage. Then the quadrature detector works at a fixed frequency (the modulation frequency), and any error due to phase shift in the amplifier is greatly reduced.Figure la shows the bridge circuit used in unbalanced bridges. This consists of a transformer, whose secondary forms the ratio arms for the variable standard capacitor Co and the impedance Z x = rx j/ Cx. The supply is connected to the primary, while the unbalance ?voltage is taken from the diagonal dc. The impedance of the secondary is usually much less than that of the capacitors: so the equivalent circuit is as in Fig. lb, in which El and E2 are the emfs of the secondaries, which are identical in phase. If and are placed along the real axis of the plex plane, we get from Fig. lb the .unbalance voltage as， (1).2102t()ReImx xdcXgjEXUj???????In which 0,1,x xxxtgrCC???, (2)210202t()()RexxxEXEX?????? (3)01220)Im(xxtg??Putting E 1 = E2 = E and modulating E 1 and E2 in accordance with and (4)39。1(sin)t???39。2(sin)mgt???In which m and f2 are the depth and frequency of the modulation ( ), we get from ?(2) and (3) that 2239。 0[(t1)]Re sinxxxEXgXEgt??????39。 022I()xxxtt?Then | | is .dcU(5)222.39。239。2 00222 02 (1)4|(Re)Im[]t [()]t1)sin(x xc xxxxxxXgXtgEXtXg???????? ?? ??????From (5) we have that for or (6)220(1)xXtg????201xxCtg?the last term under the root in (5) bees zero, i . e . , the amplitude of the envelope of the unbalance voltage bees zero. The phase of the envelope changes by at this point, so 08the envelope may be used in capacitance balancing. The systematic error in the capacitance measurement will thus depend on , being small for tanx?2tan1x??Substitution of (6) into (5) |(t1)xdcgUEm???Or for ,2tanx??