Apparatus and method of eliminating vestigial sideband pilot tone in vestigial sideband/quadrature amplitude modulation system

摘要

An apparatus and method for eliminating a vestigial sideband (VSB) pilot tone in a vestigial sideband/quadrature amplitude modulation (VSB/QAM) receiving system, is provided. This apparatus eliminates a vestigial sideband (VSB) pilot tone in a vestigial sideband/quadrature amplitude modulation (VSB/QAM) shared receiving system including a VSB/QAM shared modulator for demodulating a received VSB signal and outputting I-axis VSB symbols and Q-axis VSB symbols. This apparatus includes an I-axis pilot tone eliminating unit for dividing the I-axis VSB symbols into a plurality of groups according to the sign of a pilot tone which remains in each symbol, obtaining the size of a pilot tone by calculating the average of VSB symbols in each group, and eliminating a pilot tone by adding the size of a pilot tone to or subtracting it from the I-axis VSB symbols, and a Q-axis pilot tone eliminating unit for dividing the Q-axis VSB symbols into a plurality of groups according to the sign of a pilot tone which remains in each symbol, obtaining the size of a pilot tone by calculating the average of VSB symbols in each group, and eliminating a pilot tone by adding the size of a pilot tone to or subtracting it from the Q-axis VSB symbols. In a VSB/QAM shared receiver, a VSB signal is demodulated in synchronization with the center frequency of a VSB signal, similar to a QAM signal, in the VSB/QAM shared receiver, so that a pilot tone signal component, which, in the prior art, remained in VSB symbol values even after demodulation, can be completely eliminated.