A testing pulse for television links

As one of several test signals required for the complete waveform-testing of the video-frequency response of a television link, a pulse nominally ¿sine-squared¿ in shape and of defined width and repetition frequency has been proposed. The paper reviews the reasons for this choice of shape, and describes a pulse generator, developed for testing inks of 3-Mc/s bandwidth, in which the duration of the pulse at half-amplitudes 0.17 microsec and the normal pulse repetition frequency is 10 kc/s. The pulse-generator uses a passive network designed to have an impulse response approximating the desired pulse shape. A method of generating a very short driving pulse (about 0.035-microsec duration at half-amplitude) is then described, and details are given of certain other features which combine to make the complete pulse generator easy to operate, stable and reproducible.