Pre-emphasis thiab De-emphasis hauv FM tshaj tawm | Taw qhia

 

Hauv FM tshaj tawm, suab zoo yog qhov tseem ceeb. Tib neeg ib txwm siv zog los tsim cov thev naus laus zis tshiab los txo cov suab nrov hauv kev sib kis los txhim kho cov teeb liab suab thiab kev mloog zoo. Ob ntawm cov thev naus laus zis yog Pre-emphasis thiab De-emphasis. Koj puas to taub lawv? Qhov kev qhia no yuav qhia txog lub ntsiab lus thiab daim ntawv thov Pre-emphasis thiab De-emphasis rau koj.

   

Kev sib koom yog Kev Saib Xyuas!

 

Cov ntsiab lus

  

Emphasis yog dab tsi?

  

Qhov tseeb, Pre-emphasis thiab De-emphasis tuaj yeem hu ua emphasis ua ke. Tab sis vim li cas nws thiaj muab faib ua Pre-emphasis thiab De-emphasis? Txhawm rau teb cov lus nug no, peb yuav tsum muaj kev nkag siab yooj yim ntawm Pre-emphasis thiab De-emphasis.

Lub ntsiab lus ntawm Pre-emphasis

Kev tsom xam ua ntej yog lub tswv yim siv hauv kev xa khoom xws li FM transmitters. Nws txhais tau hais tias ua ntej qee cov txheej txheem, xws li cov teeb liab tam sim no raug xa mus rau cable, ib qho tshwj xeeb ntawm cov tswv yim zaus yuav raug txhawb los yog qhov amplitude yuav loj dua. Hauv cov lus yooj yim, lub suab ntim hauv ib qho tshwj xeeb tau tsa.

Lub ntsiab lus ntawm De-emphasis

Ntawm qhov tsis sib xws, De-emphasis yog lub tswv yim siv los txais cov khoom siv xws li FM xov tooj cua. Nws txhais tau hais tias ua ntej lub suab teeb liab hloov mus rau hauv lub suab thiab ua si, tib qhov ntau zaus yuav siv qhov kev hloov pauv mus rau qhov ua ntej. Qhov ntawd txhais tau tias, lub suab ntim hauv qhov tshwj xeeb yuav raug txo qis.

Qhov txawv ntawm Pre-emphasis thiab De-emphasis

Hauv kev xaus, Pre-emphasis thiab De-emphasis zoo ib yam, tab sis lawv tau siv rau hauv cov khoom sib txawv thiab ua haujlwm thim rov qab. Tab sis lawv ua hauj lwm rau tib lub hom phiaj - los txhim kho lub suab signals.

  

   

Qhov Kev Pom Zoo Ua Haujlwm Li Cas?

  

Pre-emphasis thiab De-emphasis ua haujlwm ua ke los txhim kho cov suab paj nruag. Tab sis lawv ua li cas thiaj ua tiav lub hom phiaj no?

Lub Suab nrov hauv Suab Teeb

Cov teeb liab nyob rau hauv cov zaus kuj muaj ntau dua cov teeb liab tsis kam, tab sis nws muaj lub suab nrov cuam tshuam lub peev xwm vim hais tias cov teeb liab nyob rau hauv kuj muaj ntau zaus muaj zog me dua cov nyob rau hauv kuj tsawg zaus. Yog li hauv xov tooj cua tshaj tawm, tshem tawm qhov kev nyiam ntawm lub suab nrov hauv qhov ntau zaus yog qhov tseem ceeb. Thiab Pre-emphasis thiab De-emphasis daws qhov teeb meem los ntawm kev txhim kho SNR ntawm cov teeb liab.

 

suab nrov-xws li 

Kev tshem tawm suab nrov

Cia peb saib yuav ua li cas Pre-emphasis thiab De-emphasis ua haujlwm ua ke los txhim kho SNR ntawm cov teeb liab.

 

Txiav txim siab qhov zaus - Pre-emphasis amplifies lub high-frequency Cheebtsam los ntawm ib tug yooj yim Pre-emphasis circuit. Ntawm no yog ib lo lus nug, yuav ua li cas los txiav txim seb qhov ntau npaum li cas yuav tsum tau amplified? Koj yuav pom muaj lub sijhawm luv ua ntej cov teeb liab tau nthuav dav. Peb hu lub sij hawm ncua lub sij hawm tas li. Nws yog xam los ntawm tus qauv T = RC, qhov twg R stands rau kev tiv thaiv nyob rau hauv lub Circuit Court thiab C sawv rau lub hwj chim mov nyob rau hauv lub Circuit Court. Feem ntau, 25μs, 50μs, thiab 75μs cov sijhawm peb lub sijhawm no muaj, thiab ntau lub tebchaws siv sijhawm sib txawv raws li tus qauv. Piv txwv li, nyob rau hauv North America thiab South Kauslim, 75μs yog siv, thiab nyob rau hauv cov teb chaws Europe, 50μs yog siv.

 

Amplify cov zaus - Yog tias 75μs siv raws li lub sijhawm tas mus li, qhov kev qhia ua ntej ntawm Circuit Court yuav linearly txhim kho cov zaus siab dua 2123 Hz ntawm tus nqi ntawm 6 dB / octave, thiab 6 dB txhais tau tias yog plaub zaug. Tom qab txhim kho cov zaus, SNR yuav raug kho kom zoo dua vim tias qhov kev nthuav dav ntawm cov zaus yuav cuam tshuam cov suab nrov hauv cov teeb liab.

 

Rov qab cov zaus - Txhawm rau kom muaj cov lus teb ib txwm muaj, yuav tsum tau ntxiv rau De-emphasis Circuit Court rau hauv xov tooj cua receiver. Ib yam li ib yam li Pre-emphasis circuit, nws muaj lub sijhawm luv luv tom qab tau txais xov tooj cua nthwv dej, thiab nws zoo ib yam li ib qho ntawm Pre-emphasis circuit. Piv txwv li, 75μs yog siv nyob rau hauv De-emphasis, ces nws yuav attenuate lub frequencies siab tshaj 2123Hz ntawm tus nqi ntawm 6dB/octave.

 

pre-emphasis-thiab-de-emphasis

 

Cov Ntawv Thov Kev Pom Zoo

 

Hauv kev tshaj tawm xov tooj cua, Pre-emphasis thiab De-emphasis tau txais yuav hauv ntau daim ntawv thov, zoo li FM tshaj tawm. Vim FM muaj qhov tshwj xeeb ntawm cov zaus siab, nws yooj yim rau kev cuam tshuam los ntawm lub suab nrov. Pre-emphasis thiab De-emphasis tuaj yeem txhim kho SNR hauv cov cim qhia tau zoo. Ntxiv nrog rau kev sib kis ntawm cov teeb liab analog, kev xa xov digital txais kev pom zoo ib yam. Zoo ib yam li analog kis tau tus mob, digital kis tau tus mob siv Emphasis rau kho qhov distortion hauv kev xa cov teeb liab ntawm cov ntaub ntawv siab. 

  

Cov Lus Nug

1. Q: Dab tsi yog qhov tseem ceeb hauv FM?

A: Nws yog cov txheej txheem uas lub teeb liab tau hloov pauv thiab rov qab mus rau qhov qub thaum kawg.

 

Nyob rau hauv cov txheej txheem ntawm kev kaw thiab tshaj tawm, txhawm rau txhim kho cov teeb liab zoo, qhov tseem ceeb yog tias lub teeb liab tau hloov pauv ua ntej kaw lossis xa tawm, thiab cov txheej txheem tom ntej ntawm lwm qhov kawg uas rov qab cov teeb liab mus rau nws lub xeev qub. Qhov piv txwv tshaj plaws hauv kev kaw suab yog txo suab nrov.

2. Q: Vim li cas thiaj siv tau ntawm FM Transmitter?

A: Vim tias nws yog siv los txhim kho SNR thiab txo qhov kev hlub ntawm lub suab nrov.

 

Nyob rau hauv tus txheej txheem ntawm kev soj ntsuam ib zaus-modulated teeb liab, lub receiver yuav tsim ib lub suab nrov spectrum uas nce nyob rau hauv zaus. Kev tsom xam ua ntej nce qhov amplitude ntawm cov teeb liab ntau dua, yog li txhim kho SNR thiab txo qhov kev nyiam ntawm lub suab nrov. Cov zoo tshaj plaws muag FM transmitters los ntawm FMUSER tau nruab nrog cov cuab yeej tshiab tshaj plaws ua ntej, yog tias koj txaus siab rau nws, tshawb xyuas nws.

3. Q: FM signals yog dab tsi?

A: Lawv yog cov teeb liab uas encode cov ntaub ntawv los ntawm kev hloov lub instantaneous zaus ntawm yoj.

 

FM signals tau dav siv hauv kev suav, kev sib txuas lus thiab kev teeb tsa. Lawv nqa cov ntaub ntawv nyob rau hauv daim ntawv ntawm cov instantaneous zaus hloov ntawm nthwv dej.

4. Q: Dab tsi yog qhov ntau ntawm FM signals?

A: 87.5 -108.0 MHz, 76.0 - 95.0 MHz, 65.8 - 74.0 MHz.

 

87.5 - 108.0 MHz yog qhov siv ntau zaus thoob ntiaj teb. Thiab 76.0 - 95.0 MHz yog siv nyob rau hauv Nyiv, 65.8 - 74.0 MHz yog tsuas yog siv nyob rau hauv lub teb chaws nyob rau hauv Western Europe. 

     

    xaus

     

    Hais txog qhov twg, peb paub tias Kev Taw Qhia yog qhov kev siv thev naus laus zis hauv xov tooj cua tshaj tawm, nws ua tau zoo txhim kho cov xov tooj cua hauv kev sib kis. FMUSER yog cov khoom siv xov tooj cua tshaj lij tshaj lij, koj tuaj yeem yuav FM transmitters zoo ntawm tus nqi txaus siab. Yog tias koj xav yuav FM xov tooj cua transmitters nrog ua ntej, thov yim rau hu rau FMUSER

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