A velocity-modulation television system

The paper describes a complete television system operating on the velocity-modulation principle. The theory, advantages, and limitations, of the principle are discussed, and it is shown how these limitations are overcome by the use of a further principle, that of intensification. The practical development of the system is described in detail, particular attention being given to the transmitting end, where the most fundamental problems are encountered. The results obtained to date (with single-channel wire transmission) are specified. The complete system is shown to be characterized by the following features:¿ (a) Absence of synchronizing problem in the line-scanning direction. (b) Simple solution of synchronizing problem in the picturetraversing direction, including automatic framing. (c) Greatly relaxed modulation requirements on the receiving oscillograph. (d) Increased picture-brightness for a given receiving oscillograph as compared with the intensity-modulation system. (e) Favourable concentration of detail in the light portions of the picture. (f) Nearly constant percentage modulation of radio transmitter.