MEASUREMENT AND REDUCTION OF HIGH FREQUENCY NOISE FROM A DISPLAY TERMINAL.

High frequency noise in the 16 KHz octave band emitted by a visual display terminal could be a major source of annoyance to users. Noise can be generated as a discrete tone at the line scan frequency of the display crt by the electronic components driven at the sweep frequency. These components are generally associated with the analog card, switching mode power supply and crt yoke. This paper describes a high frequency noise reduction program carried out on a display terminal with details of the experimental technique used to give consistent measurements of high frequency noise, isolation of the noise sources to the component level, noise reduction techniques and the correlation between measurements made in a small reverberation room with those made in standard sized rooms.