Lub ntsiab lus ntawm qhov hnyav hnyav ntawm lub suab Level Meters
Teeb liab Noise Ratio (SNR)
Nws hais txog qhov piv ntawm cov teeb liab muaj txiaj ntsig rau lub suab nrov tsis muaj zog. Feem ntau ntsuas hauv beta. Vim tias lub zog yog qhov ua haujlwm ntawm qhov tam sim no thiab qhov hluav taws xob, lub teeb liab-rau-suab nrov piv kuj tuaj yeem suav nrog cov nqi hluav taws xob, uas yog qhov piv ntawm cov teeb liab rau theem suab nrov. Txawm li cas los xij, cov qauv kev suav yog txawv me ntsis. Xam cov teeb liab-rau-nruab nrab raws li lub zog piv: S/N=10 log Xam cov teeb liab-rau- suab nrov piv raws li qhov voltage: S/N=10 log Vim logarithmic kev sib raug zoo ntawm teeb liab-rau -noise ratio thiab lub hwj chim los yog voltage, nws yog ib qho tsim nyog yuav tsum tau nce qhov sib piv ntawm cov nqi tso zis rau lub suab nrov. Piv txwv li, thaum lub teeb liab-rau- suab nrov piv yog 100dB, qhov tso zis voltage yog 10000 npaug ntawm lub suab nrov. Rau hluav taws xob circuits, qhov no tsis yog ib txoj haujlwm yooj yim.
Yog hais tias lub amplifier muaj lub teeb liab-rau-suab nrov piv, nws txhais tau hais tias sab qaum teb saib nyob ntsiag to. Vim lub suab nrov qis, ntau lub suab tsis muaj zog cov ntsiab lus npog los ntawm lub suab nrov yuav tshwm sim, ua rau muaj suab nrov nrov, ua kom pom huab cua zoo dua, thiab muaj zog ntau ntxiv. Tsis muaj cov ntaub ntawv kev ntxub ntxaug nruj rau kev ntsuas seb lub teeb liab-rau-nruab nrab ntawm lub amplifier puas zoo lossis phem. Feem ntau hais lus, nws yog qhov zoo dua nyob ib puag ncig 85dB lossis siab dua. Yog tias nws qis dua qhov pib, nws tuaj yeem hnov cov suab nrov hauv cov suab paj nruag sib txawv thaum lub sijhawm mloog suab nrov. Ntxiv nrog rau qhov sib piv ntawm cov teeb liab-rau-lub suab nrov, lub tswv yim ntawm cov suab nrov kuj tuaj yeem siv los ntsuas cov suab nrov ntawm amplifiers. Qhov no yog qhov tseeb-rau-lub suab piv tus nqi suav nrog qhov voltage, tab sis tus denominator yog tus lej tas: 0.775V, thiab tus lej yog lub suab nrov. Yog li ntawd, qhov sib txawv ntawm lub suab nrov thiab lub teeb liab-rau-nruab piv piv yog: tus qub yog tus lej tiag, thaum tom kawg yog tus lej txheeb ze.
Tom qab cov lus qhia tshwj xeeb hauv cov khoom siv phau ntawv, feem ntau muaj lo lus A, lub ntsiab lus A-qhov hnyav, uas txhais tau tias A hnyav. Qhov hnyav hais txog kev hloov kho ib qho nqi raws li qee txoj cai. Vim lub rhiab heev ntawm tib neeg pob ntseg mus rau nruab nrab zaus cov khoom, yog hais tias lub teeb liab-rau-s suab nrov piv ntawm ib tug amplifier nyob rau hauv lub intermediate zaus band yog loj txaus, txawm tias lub teeb liab-rau-suab nrov piv yog me ntsis qis dua qhov qis thiab siab. zaus bands, nws tsis yog ib qho yooj yim rau tib neeg pob ntseg mus ntes. Nws tuaj yeem pom tau tias yog siv txoj kev hnyav los ntsuas qhov sib piv ntawm lub teeb liab-rau-lub suab nrov, nws tus nqi yuav twv yuav raug siab dua yog tias tsis siv txoj kev hnyav. Nyob rau hauv cov nqe lus ntawm A qhov hnyav, nws tus nqi siab dua yam tsis xav txog qhov hnyav.
Tsis tas li ntawd, txhawm rau simulate qhov sib txawv rhiab heev ntawm tib neeg kev hnov lus pom ntawm ntau zaus, muaj lub network hauv lub suab ntsuas ntsuas uas tuaj yeem simulate cov yam ntxwv ntawm tib neeg lub pob ntseg thiab kho cov teeb liab hluav taws xob kom kwv yees qhov kev hnov lus. Lub network no hu ua lub network hnyav. Lub suab siab ntsuas ntsuas los ntawm qhov hnyav network tsis yog lub hom phiaj lub cev muaj nuj nqis (hu ua linear suab siab theem), tab sis lub suab siab kho los ntawm kev hnov lus pom, hu ua hnyav suab qib lossis suab nrov.
Feem ntau muaj peb hom kev tes hauj lwm hnyav: A, B, thiab C. A-hnyav suab theem simulates cov yam ntxwv zaus ntawm cov suab nrov qis qis qis dua 55dB hauv tib neeg pob ntseg, B-weighted suab theem simulates cov yam ntxwv zaus ntawm nruab nrab siv suab nrov los ntawm 55dB txog 85dB, thiab C-weighted suab theem simulates tus yam ntxwv zaus ntawm kev siv suab nrov. Qhov sib txawv tseem ceeb ntawm peb yog qhov ntsuas ntawm attenuation ntawm cov suab nrov qis, nrog A muaj qhov attenuation tshaj plaws, B yog qhov thib ob, thiab C muaj qhov tsawg tshaj plaws. Vim nws cov yam ntxwv nkhaus ze rau cov khoom ntawm lub pob ntseg ntawm tib neeg lub pob ntseg, A-weighted suab theem tam sim no tau siv dav hauv kev ntsuas suab nrov hauv ntiaj teb, thaum B thiab C maj mam tsis siv.
