Preparing several TV signals for transmission - involves frequency conversion and multiplexing with additional digital filter preceding channel bandpass filter with same clock rate

摘要

A conventional digital frequency converter consists of an anti-aliasing analog filter (AAF), a digitiser (A/D), a channel band pass filter (CHBF), a digital modulator, a complex interpolation filter raising the sampling rate by a given factor (L), and an adder (+) of corresp. outputs from other branches of the circuit. The adder inserts a digital filter (RBF) having real coeffts., scanned at the same rate (fA) with at least half of its coeffts. equal to zero. USE/ADVANTAGE - For broadband cable TV distribution networks, with complexity of the analog portion greatly reduced.