A variable time-equalizer for video-frequency waveform correction

A description is given of an experimental variable waveform-corrector for reducing distortion in imperfectly equalized video-frequency links. It operates on the time-equalizer principle, whereby a wide variety of transmission characteristics may be obtained by combining the input signal with a series of both advanced and retarded ¿echoes¿ or attenuated replicas of itself, each echo being individually adjustable in amplitude and sign. The requirements and principles of a practical design based on the ransversal type suggested by Blumlein, Kallmann and Percival are discussed, with particular reference to the problem of adjusting and combining the outputs of a series of tappings along a delay line.