Provided is a modulation apparatus that can reduce time
delay of on-channel repeaters in a terrestrial
digital television broadcasting system. The time
delay is caused by a filter during the modulation operation in the on-channel repeaters. The modulation apparatus of the present research includes: a
baseband signal forming unit for forming a
baseband signal by combining the output signals of an
equalization unit with the pre-defined field / segment synchronization signals in the on-channel repeaters; a
pilot inserting unit for inserting a
pilot signal to the
baseband signal; an up-sampling unit for up-sampling the baseband signal with the
pilot signal; a VSB filtering unit for filtering the up-sampled baseband signal based on a Window technique and / or an Equi-
Ripple filter to thereby form an in-phase (I) signal and a quadrature (Q) signal; an up-converting unit for up-converting the frequencies of the filtered I and Q signals to frequencies of an
intermediate frequency (IF) band; an adding unit for adding the up-converted I and Q signals and converting a
resultant signal into a digital VSB signal of the IF band; and a digital-to-analogue converting unit for converting the
digital signal of the IF band to an analogue signal.