The measurement of random monochrome video interference

ONE OF the important factors in the design and maintenance of television transmission circuits is random interference, sometimes referred to as random noise. Much of this type of interference originates in the input stages of amplifiers but it may also originate in the line or in other parts of the transmission path. These noise components are greatly modified by circuit equalization which may vary from a few decibels (db) to possibly 27 or more db per octave. Thus the transmission engineer is confronted with the problem of evaluating random interference having different energy levels, per cycle, over the television bandwidth. Before noise evaluations can be made, information must be obtained by subjective tests on the interfering effect of broad, narrow, and mixed bands of random noise distributed throughout the television band.