Third octave filter system - has filters connected in cascade whose central frequencies are shifted as well as binary-decimal switching means

摘要

The third octave filter system with central variable frequency is for pass band circuits whose central frequency valve is controlled by a selector. The system has cascade filters whose central frequencies are shifted. The value of the central frequency is controlled by a selector having at least a binary-decimal decoder. The selector has also manual switching means and step by step switching means and programmed switching means (7). Each filter is fitted with branches each having a capacitor connected in series with field effect transistors.