Electron Beam Deflection Tube for Pulse Code Modulation
01 January 1948
O U L S E code transmission systems 1 in which successive signal amplitude samples are transmitted by pulse code groups require special modulators. The essential operational requirements of a pulse code modulator are: (1) to quantize or measure the signal amplitude sample to the nearest step in the discrete amplitude scale transmitted by the pulse code system, and (2) to generate the group of on-off pulses identifying the step. Several methods have been proposed 2 - 3 - 4 in which quantization and pulse formation were performed with circuits employing conventional electron tubes. The circuits involved sequential and comparison operations and were not easily adapted to a multi-channel time division system because of limitations in coding speeds and the complexity of the equipment. An electron beam deflection tube has been developed which, together with associated beam positioning and sweep circuits, performs the modulation rapidly, making possible the sequential modulation of a number of channels in time division multiplex. The electronic principles, design and characteristics of the experimental tube are described in the present paper. CONVERSION FROM SIGNAL INPUT TO PULSE CODE OUTPUT