Patent ID: 6618096
Filing Date: 2003-09-09
Classification: H03C,H04L,H04N

Abstract:
A digital signal processing vestigial-sideband television modulator comprising:means for receiving a television signal; means for digitizing said television signal to generate a digital video signal; means for digitally processing said digital video signal to generate a complex baseband signal, wherein said digitally processing means digitally clamps said digital video signal; provides group delay predistortion to said digital video signal; and band limits said digital video signal using a digital signal processing technique; means for converting said complex baseband signal into an in-phase baseband signal and a quadrature baseband signal; means for modulating said in-phase baseband signal and said quadrature baseband signal to respectively generate a modulated in-phase baseband signal and a modulated quadrature baseband signal; means for combining said modulated in-phase baseband signal and said modulated quadrature baseband signal to produce a vestigial radio frequency television signal; means for tapping off intermodulation distortion of said vestigial radio frequency television signal; means for filtering said intermodulation distortion wherein the means for filtering comprises a bandpass filter with a passband centered on the second order intermodulation product of Wc+2Wm selected for minimizing signal power and carrier leakage, wherein Wc is the frequency of the carrier leakage and Wm is the frequency of the undesired mixing products; means for detecting the power level of said intermodulation distortion; and means for compensating imbalances in said modulating means using said detected power level of said intermodulation distortion wherein imbalances include amplitude imbalance, phase imbalance and DC offsets.