Nrog rau txoj kev loj hlob ntawm kuv lub teb chaws cable TV, rau TV modulator khoom, nws plays ib tug tseem ceeb luag hauj lwm nyob rau hauv kho cov teeb liab. Nyob rau hauv qhov tseeb, raws li ib tug modulator, nws yog tsuas yog ib qho tseem ceeb txuas nyob rau hauv ib tug modulated DC amplifier Circuit Court.
Tom qab DC teeb liab ui yuav tsum tau amplified dhau los ntawm PBI modulator, nws dhau los ua AC teeb liab U; Tom qab tau amplified los ntawm AC amplifier, nws yog thaum kawg hloov mus rau hauv DC tso zis teeb liab UO los ntawm tus demodulator; lub oscillator generates ib tug switching teeb liab U; nws yog siv los tswj lub modulator Sampling nkaus. Txij li thaum lub teeb liab amplification ua hauj lwm tsuas yog ua tiav los ntawm AC amplifier, thiab xoom drift ntawm AC amplifier yog negligible, xoom drift ntawm modulator thiab demodulator kuj yuav ua tau me me heev, yog li cov modulated DC amplifier yuav siv tau los amplify tsis muaj zog. DC teeb liab,
PBI modulators feem ntau tuaj nyob rau hauv peb hom: mechanical modulators (mechanical choppers), transistor modulators, thiab FET modulators. Raws li daim ntawv Circuit Court, nws tuaj yeem muab faib ua parallel modulators thiab serial thiab parallel modulators. Cov tom kawg muaj kev ua tau zoo dua li yav dhau los, tab sis cov qauv yog qhov nyuaj.
