目前，導波雷達物位計已經廣泛應用于石油、化工等各個(ge)領域(yu)的水(shui)、油、固體物料(liao)等的接觸測(ce)量(liang)(liang)(liang)，取得了非常不錯(cuo)的效果。它的測(ce)量(liang)(liang)(liang)準確度是比較不錯(cuo)的，但(dan)是也有一些因素會導致測(ce)量(liang)(liang)(liang)誤差的出現，今天我們從兩方(fang)面(mian)分析導波雷達物位計測(ce)量(liang)(liang)(liang)誤差的來源。

我(wo)們(men)從兩(liang)個方面分(fen)析，導波(bo)雷(lei)(lei)達物(wu)位(wei)計(ji)測(ce)量誤差的(de)(de)(de)(de)來源，第一就是(shi)硬(ying)件誤差，導波(bo)雷(lei)(lei)達物(wu)位(wei)計(ji)根(gen)據(ju)時(shi)(shi)域(yu)反(fan)射(she)(she)原理(li)測(ce)量，雷(lei)(lei)達主(zhu)機(ji)的(de)(de)(de)(de)時(shi)(shi)基電路產生脈(mo)(mo)(mo)(mo)沖(chong)(chong)波(bo)形(xing)，信(xin)號(hao)分(fen)為兩(liang)條路徑。一種(zhong)方式經(jing)預觸(chu)發(fa)(fa)(fa)電路放大(da)整形(xing)，成為幅度較(jiao)大(da)、前沿(yan)抖(dou)動的(de)(de)(de)(de)脈(mo)(mo)(mo)(mo)沖(chong)(chong)信(xin)號(hao)，送(song)(song)至脈(mo)(mo)(mo)(mo)沖(chong)(chong)發(fa)(fa)(fa)射(she)(she)器(qi)。脈(mo)(mo)(mo)(mo)沖(chong)(chong)發(fa)(fa)(fa)射(she)(she)器(qi)通過發(fa)(fa)(fa)射(she)(she)天(tian)線沿(yan)探頭發(fa)(fa)(fa)射(she)(she)周期(qi)性窄脈(mo)(mo)(mo)(mo)沖(chong)(chong)電磁波(bo)，在界面上反(fan)射(she)(she)后，形(xing)成一系(xi)列回(hui)波(bo)信(xin)號(hao)，由接收天(tian)線接收并(bing)發(fa)(fa)(fa)送(song)(song)到(dao)等效時(shi)(shi)間(jian)(jian)采(cai)(cai)(cai)樣(yang)(yang)(yang)電路。另一種(zhong)是(shi)給采(cai)(cai)(cai)樣(yang)(yang)(yang)脈(mo)(mo)(mo)(mo)沖(chong)(chong)發(fa)(fa)(fa)生器(qi)產生采(cai)(cai)(cai)樣(yang)(yang)(yang)脈(mo)(mo)(mo)(mo)沖(chong)(chong)來控制等效時(shi)(shi)間(jian)(jian)采(cai)(cai)(cai)樣(yang)(yang)(yang)電路，等效時(shi)(shi)間(jian)(jian)采(cai)(cai)(cai)樣(yang)(yang)(yang)電路對(dui)回(hui)波(bo)信(xin)號(hao)進(jin)行采(cai)(cai)(cai)樣(yang)(yang)(yang)，然后將其轉化(hua)為中低頻信(xin)號(hao)，送(song)(song)至單片機(ji)。根(gen)據(ju)雷(lei)(lei)達原理(li)中對(dui)雷(lei)(lei)達距(ju)離分(fen)辨(bian)率的(de)(de)(de)(de)定(ding)義可以看出，脈(mo)(mo)(mo)(mo)沖(chong)(chong)雷(lei)(lei)達所能分(fen)辨(bian)的(de)(de)(de)(de)目標之間(jian)(jian)的(de)(de)(de)(de)最小距(ju)離與(yu)發(fa)(fa)(fa)射(she)(she)脈(mo)(mo)(mo)(mo)沖(chong)(chong)的(de)(de)(de)(de)寬度有(you)關。越大(da)，影(ying)響測(ce)量的(de)(de)(de)(de)精(jing)度，發(fa)(fa)(fa)射(she)(she)脈(mo)(mo)(mo)(mo)沖(chong)(chong)的(de)(de)(de)(de)寬度也會影(ying)響測(ce)量的(de)(de)(de)(de)精(jing)度。

另(ling)一(yi)(yi)個(ge)(ge)是(shi)(shi)軟件誤(wu)(wu)(wu)差(cha)(cha)(cha)，信(xin)(xin)號(hao)(hao)處(chu)(chu)理中(zhong)(zhong)(zhong)(zhong)的(de)(de)(de)(de)粗(cu)大誤(wu)(wu)(wu)差(cha)(cha)(cha)來自于(yu)對物(wu)(wu)(wu)位(wei)(wei)(wei)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)和(he)(he)丟(diu)失(shi)波(bo)(bo)(bo)的(de)(de)(de)(de)錯誤(wu)(wu)(wu)判(pan)(pan)斷(duan)，前者主要是(shi)(shi)信(xin)(xin)號(hao)(hao)處(chu)(chu)理方式造成(cheng)的(de)(de)(de)(de)，后者是(shi)(shi)硬(ying)件條(tiao)件和(he)(he)環境造成(cheng)的(de)(de)(de)(de)。物(wu)(wu)(wu)位(wei)(wei)(wei)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)是(shi)(shi)來自介質表面的(de)(de)(de)(de)反射(she)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)，在(zai)(zai)采集到的(de)(de)(de)(de)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)信(xin)(xin)號(hao)(hao)中(zhong)(zhong)(zhong)(zhong)，除了物(wu)(wu)(wu)位(wei)(wei)(wei)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)外(wai)，還有(you)其(qi)他因(yin)(yin)素(su)產生(sheng)的(de)(de)(de)(de)反射(she)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)，統稱(cheng)為噪(zao)(zao)聲(sheng)(sheng)。以物(wu)(wu)(wu)位(wei)(wei)(wei)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)信(xin)(xin)號(hao)(hao)的(de)(de)(de)(de)頻(pin)率(lv)為參考(kao)，噪(zao)(zao)聲(sheng)(sheng)可(ke)分為高頻(pin)噪(zao)(zao)聲(sheng)(sheng)和(he)(he)物(wu)(wu)(wu)位(wei)(wei)(wei)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)同(tong)(tong)頻(pin)噪(zao)(zao)聲(sheng)(sheng)兩類。其(qi)中(zhong)(zhong)(zhong)(zhong)，高頻(pin)噪(zao)(zao)聲(sheng)(sheng)對應(ying)白噪(zao)(zao)聲(sheng)(sheng)的(de)(de)(de)(de)高頻(pin)部分，由(you)于(yu)工作條(tiao)件、電源(yuan)干擾(rao)、儀器(qi)不穩定(ding)(ding)(ding)、障礙(ai)物(wu)(wu)(wu)產生(sheng)的(de)(de)(de)(de)尖峰(feng)(feng)或突變(bian)信(xin)(xin)號(hao)(hao)等原因(yin)(yin)，被認為是(shi)(shi)信(xin)(xin)號(hao)(hao)同(tong)(tong)頻(pin)噪(zao)(zao)聲(sheng)(sheng)。可(ke)見，如果不能將電平(ping)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)與各種噪(zao)(zao)聲(sheng)(sheng)區分開(kai)來，就會造成(cheng)對真實(shi)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)的(de)(de)(de)(de)誤(wu)(wu)(wu)判(pan)(pan)，從而產生(sheng)粗(cu)差(cha)(cha)(cha)。在(zai)(zai)導波(bo)(bo)(bo)雷達物(wu)(wu)(wu)位(wei)(wei)(wei)計(ji)的(de)(de)(de)(de)信(xin)(xin)號(hao)(hao)處(chu)(chu)理中(zhong)(zhong)(zhong)(zhong)，可(ke)以看(kan)出即(ji)使是(shi)(shi)同(tong)(tong)一(yi)(yi)物(wu)(wu)(wu)位(wei)(wei)(wei)的(de)(de)(de)(de)測量值(zhi)(zhi)也不穩定(ding)(ding)(ding)，呈現(xian)上下波(bo)(bo)(bo)動的(de)(de)(de)(de)特點(dian)(dian)(dian)(dian)，因(yin)(yin)此存(cun)在(zai)(zai)隨(sui)機(ji)(ji)誤(wu)(wu)(wu)差(cha)(cha)(cha)。另(ling)外(wai)，在(zai)(zai)實(shi)驗(yan)測量過程中(zhong)(zhong)(zhong)(zhong)，標準值(zhi)(zhi)是(shi)(shi)用(yong)鋼(gang)尺(chi)或米尺(chi)讀(du)取的(de)(de)(de)(de)。由(you)于(yu)鋼(gang)尺(chi)或米尺(chi)的(de)(de)(de)(de)精度(du)限(xian)制，讀(du)數(shu)不可(ke)避(bi)免地存(cun)在(zai)(zai)隨(sui)機(ji)(ji)誤(wu)(wu)(wu)差(cha)(cha)(cha)。信(xin)(xin)號(hao)(hao)處(chu)(chu)理中(zhong)(zhong)(zhong)(zhong)的(de)(de)(de)(de)系統誤(wu)(wu)(wu)差(cha)(cha)(cha)主要存(cun)在(zai)(zai)于(yu)傳(chuan)播(bo)時間的(de)(de)(de)(de)計(ji)算中(zhong)(zhong)(zhong)(zhong)，其(qi)中(zhong)(zhong)(zhong)(zhong)，回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)定(ding)(ding)(ding)位(wei)(wei)(wei)點(dian)(dian)(dian)(dian)的(de)(de)(de)(de)選擇(ze)是(shi)(shi)傳(chuan)播(bo)時間計(ji)算的(de)(de)(de)(de)關鍵(jian)，電平(ping)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)波(bo)(bo)(bo)形(xing)類似于(yu)鐘形(xing)曲線，有(you)一(yi)(yi)定(ding)(ding)(ding)的(de)(de)(de)(de)寬度(du)，有(you)一(yi)(yi)個(ge)(ge)峰(feng)(feng)值(zhi)(zhi)點(dian)(dian)(dian)(dian)、一(yi)(yi)個(ge)(ge)上升沿和(he)(he)一(yi)(yi)個(ge)(ge)下降沿。應(ying)選擇(ze)幅度(du)相(xiang)對穩定(ding)(ding)(ding)且對距(ju)離變(bian)化敏感的(de)(de)(de)(de)位(wei)(wei)(wei)置作為回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)固定(ding)(ding)(ding)點(dian)(dian)(dian)(dian)，通常選擇(ze)回(hui)(hui)(hui)(hui)波(bo)(bo)(bo)峰(feng)(feng)值(zhi)(zhi)點(dian)(dian)(dian)(dian)作為錨點(dian)(dian)(dian)(dian)。但由(you)于(yu)信(xin)(xin)號(hao)(hao)本身的(de)(de)(de)(de)分辨(bian)率(lv)較低，即(ji)使在(zai)(zai)同(tong)(tong)一(yi)(yi)液位(wei)(wei)(wei)下，峰(feng)(feng)值(zhi)(zhi)點(dian)(dian)(dian)(dian)也會有(you)1~2個(ge)(ge)點(dian)(dian)(dian)(dian)的(de)(de)(de)(de)波(bo)(bo)(bo)動。另(ling)外(wai)，實(shi)際中(zhong)(zhong)(zhong)(zhong)會出現(xian)平(ping)頂峰(feng)(feng)值(zhi)(zhi)波(bo)(bo)(bo)形(xing)，無(wu)法(fa)確(que)定(ding)(ding)(ding)真正的(de)(de)(de)(de)峰(feng)(feng)值(zhi)(zhi)點(dian)(dian)(dian)(dian)，導致在(zai)(zai)一(yi)(yi)個(ge)(ge)液位(wei)(wei)(wei)上確(que)定(ding)(ding)(ding)的(de)(de)(de)(de)峰(feng)(feng)值(zhi)(zhi)點(dian)(dian)(dian)(dian)相(xiang)同(tong)(tong)，也會造成(cheng)誤(wu)(wu)(wu)差(cha)(cha)(cha)。

以上(shang)就是造成導(dao)波雷達物位(wei)計(ji)測量誤差的兩方面原因(yin)，至(zhi)于如何去修正誤差，提高導(dao)波雷達物位(wei)計(ji)測量的準確度(du)，我們也會出(chu)一篇文章為大家解密(mi)。