傳感器的低頻截止頻率

與傳感器的高頻截止頻率類同，低頻截止頻率是指在所規定的傳感器頻率響應幅值誤差（±5%
， ±10% 或 ±3dB）內(nei)傳(chuan)感(gan)器(qi)所(suo)能(neng)測(ce)量(liang)的(de)最(zui)低(di)頻(pin)率(lv)信(xin)號(hao)。誤(wu)差(cha)值(zhi)越(yue)大(da)其(qi)低(di)頻(pin)截(jie)止(zhi)頻(pin)率(lv)也(ye)相(xiang)對(dui)越(yue)低(di)。所(suo)以(yi)不(bu)同(tong)傳(chuan)感(gan)器(qi)的(de)低(di)頻(pin)截(jie)止(zhi)頻(pin)率(lv)指(zhi)標(biao)必(bi)須(xu)在(zai)相(xiang)同(tong)的(de)誤(wu)差(cha)條(tiao)件(jian)下(xia)進(jin)行(xing)比(bi)較(jiao)。

 
圖1：壓電式加速度傳感器

低di阻zu抗kang電dian壓ya輸shu出chu型xing傳chuan感gan器qi的de低di頻pin特te性xing是shi由you傳chuan感gan器qi敏min感gan芯xin體ti和he內nei置zhi電dian路lu的de綜zong合he電dian參can數shu所suo決jue定ding的de。其qi頻pin率lv響xiang應ying特te性xing可ke以yi用yong模mo擬ni電dian路lu的de一yi階jie高gao通tong濾lv波bo器qi特te性xing來lai描miao述shu，所suo以yi傳chuan感gan器qi的de低di頻pin響xiang應ying和he截jie止zhi頻pin率lv完wan全quan可ke以yi用yong一yi階jie係xi統tong的de時shi間jian常chang數shu來lai確que定ding。從cong實shi用yong角jiao度du來lai看kan，由you於yu傳chuan感gan器qi的de甚shen低di頻pin頻pin率lv響xiang應ying的de標biao定ding比bi較jiao困kun難nan
，而er通tong過guo傳chuan感gan器qi對dui時shi間jian域yu內nei階jie躍yue信xin號hao的de響xiang應ying可ke測ce得de傳chuan感gan器qi的de時shi間jian常chang數shu；yinciliyongchuanganqidedipinxiangyingyuyijiegaotonglvboqidetexingjihuyizhidetedian，tongguojisuankefangbiandihuodechuanganqidedipinxiangyingheyuqiduiyingdedipinjiezhipinlv。

傳感器的靈敏度，低頻噪聲特性和動態響應範圍

低頻測量的傳感器一般要求有比較高的靈敏度以滿足低頻小信號的測量。靈敏度的增加往往是有限的。加速度傳感器靈敏度是能達到10V/g 或(huo)更(geng)高(gao)，但(dan)是(shi)靈(ling)敏(min)度(du)高(gao)往(wang)往(wang)帶(dai)來(lai)其(qi)他(ta)的(de)負(fu)麵(mian)效(xiao)應(ying)，比(bi)如(ru)傳(chuan)感(gan)器(qi)的(de)穩(wen)定(ding)性(xing)，抗(kang)過(guo)載(zai)能(neng)力(li)
，以(yi)及(ji)對(dui)周(zhou)邊(bian)環(huan)境(jing)幹(gan)擾(rao)的(de)敏(min)感(gan)性(xing)。因(yin)此(ci)追(zhui)求(qiu)過(guo)高(gao)靈(ling)敏(min)度(du)並(bing)不(bu)一(yi)定(ding)能(neng)解(jie)決(jue)微(wei)小(xiao)信(xin)號(hao)的(de)測(ce)量(liang)，相(xiang)反(fan)高(gao)分(fen)辨(bian)率(lv)和(he)低(di)噪(zao)聲(sheng)的(de)傳(chuan)感(gan)器(qi)在(zai)工(gong)程(cheng)應(ying)用(yong)中(zhong)往(wang)往(wang)更(geng)容(rong)易(yi)解(jie)決(jue)實(shi)際(ji)問(wen)題(ti)。所(suo)以(yi)選(xuan)用(yong)具(ju)有(you)低(di)電(dian)噪(zao)聲(sheng)的(de)傳(chuan)感(gan)器(qi)在(zai)低(di)頻(pin)測(ce)量(liang)中(zhong)尤(you)為(wei)重(zhong)要(yao)。

 
圖2：壓電式加速度傳感器內部結構

為wei了le表biao明ming傳chuan感gan器qi所suo能neng測ce量liang的de最zui小xiao信xin號hao大da部bu分fen商shang業ye化hua的de加jia速su度du計ji也ye都dou提ti供gong分fen辨bian率lv或huo電dian噪zao聲sheng指zhi標biao。國guo內nei絕jue大da部bu分fen傳chuan感gan器qi的de寬kuan帶dai電dian噪zao聲sheng指zhi標biao一yi般ban都dou標biao為wei20μV，而BW-sensor的寬帶電噪聲指標已降低到10μV。然而對低頻小信號測量來說，僅提供寬頻帶的電噪聲並不能完全反映傳感器在低頻範圍內加速度測量的分辨率
；這是因為由內置電路引起的低頻噪聲大小與頻率的倒數成正比，即所謂1/f噪(zao)聲(sheng)，當(dang)測(ce)量(liang)頻(pin)率(lv)很(hen)低(di)時(shi)傳(chuan)感(gan)器(qi)的(de)電(dian)噪(zao)聲(sheng)輸(shu)出(chu)按(an)指(zhi)數(shu)幅(fu)度(du)增(zeng)長(chang)。所(suo)以(yi)傳(chuan)感(gan)器(qi)的(de)低(di)頻(pin)電(dian)噪(zao)聲(sheng)的(de)數(shu)值(zhi)與(yu)寬(kuan)帶(dai)電(dian)噪(zao)聲(sheng)指(zhi)標(biao)是(shi)完(wan)全(quan)不(bu)同(tong)的(de)而(er)且(qie)頻(pin)率(lv)越(yue)低(di)這(zhe)種(zhong)差(cha)別(bie)越(yue)明(ming)顯(xian)。因(yin)此(ci)用(yong)於(yu)甚(shen)低(di)頻(pin)測(ce)量(liang)的(de)傳(chuan)感(gan)器(qi)其(qi)分(fen)辨(bian)率(lv)常(chang)用(yong)傳(chuan)感(gan)器(qi)輸(shu)出(chu)電(dian)噪(zao)聲(sheng)的(de)功(gong)率(lv)譜(pu)密(mi)度(du)表(biao)示(shi)。此(ci)指(zhi)標(biao)的(de)實(shi)用(yong)意(yi)義(yi)是(shi)傳(chuan)感(gan)器(qi)在(zai)特(te)定(ding)頻(pin)率(lv)下(xia)的(de)噪(zao)聲(sheng)大(da)小(xiao)，其(qi)單(dan)位(wei)是(shi)一(yi)般(ban)用(yong)μV/√Hz或μg/√Hz來表示。BW-sensor 內置電路電噪聲功率譜密度的典型值為3μV/√Hz@ 10 Hz。

傳感器的瞬態溫度響應對低頻測量的影響

youyuyadiantaocidetexing
，yadianshijiasudujiduiwendudeturanbianhuadouhuichanshengbutongchengdudedianheshuchu。chuanganqideshuntaiwenduxiangyingzhibiaojiushihengliangchuanganqiduiwendubianhuademinganchengdu。zheduidipinceliangyouweizhongyao。youyudipinceliangdexinhaohenxiao
，erchuanganqiyinhuanjingwendubianhuajikenengchanshengyudipinzhendongxinhaoxiangdangdewucha
；這(zhe)兩(liang)種(zhong)信(xin)號(hao)在(zai)甚(shen)低(di)頻(pin)範(fan)圍(wei)內(nei)很(hen)難(nan)區(qu)分(fen)，因(yin)此(ci)如(ru)何(he)減(jian)小(xiao)環(huan)境(jing)溫(wen)度(du)變(bian)化(hua)對(dui)傳(chuan)感(gan)器(qi)輸(shu)出(chu)的(de)影(ying)響(xiang)在(zai)低(di)頻(pin)測(ce)量(liang)中(zhong)顯(xian)得(de)非(fei)常(chang)重(zhong)要(yao)。傳(chuan)感(gan)器(qi)的(de)瞬(shun)態(tai)溫(wen)度(du)響(xiang)應(ying)指(zhi)標(biao)單(dan)位(wei)是(shi)g/oC， 表示瞬態溫度每變化一度所相當的加速度輸出，其值是通過電壓（電荷）輸出和傳感器靈敏度之間的換算得到的。

 
圖3：壓電式加速度傳感器的頻率響應

傳感器的瞬態溫度響應是由壓電材料直接導致的，因此壓電陶瓷對由溫度突變所致的電荷輸出大小決定了這一指標的好壞。BW-sensor選用目前國外綜合性能指標最好的壓電陶瓷並結合記憶金屬製成的用於低頻測量的加速度傳感器經國防兵器
、hangtianhedaxingjiegouduoniandeshiyongyanzhenglechuanganqijuyouyouyuededipinshuchuwendingxinghekangganraoxingneng。shijishendipinceliangzhong，weilejiandihuanjingwendubianhuaduichuanganqidipinxinhaoshuchudeyingxiang，chuanganqidewaikejinkenengcaiyonggerebaohutao。

傳感器的安裝基座和基座應變對測量的影響

youyudipinceliangchuanganqiduigaopinxiangyingdeyaoqiubugaoyincichuanganqishiyongrenhezhonganzhuangfangshiyibandounengmanzuyaoqiu。danxuyaozhuyilianggewenti
，qiyishichuanganqiyingjinliangkaolvshiyongjueyuandizuoyibimianrenheyouduidihuiluyinqidezaoshengyingxiangceliangxinhao。qiershiyingkaolvchuanganqianzhuangchudebeicejiegouyingbianduichuanganqishuchudeyingxiang，jichuanganqiyingbianlingmindudaxiao。jianqiejiegouxingshideyadianjiasuduchuanganqijuyoulianghaodejizuoyingbiantexing

，yibandounengmanzutongchangdedipinjiegouceshi。ruguojiegouyingbianguodaduichuanganqideceliangxinhaoyouyingxiang
，ketongguojianxiaochuanganqiyubeicejiegouzhijiandejiechumianjilaijiangdijiegouyingbianduichuanganqiceliangdailaideyingxiang。