The visibility of noise in system I PAL colour television
A. Oliphant, Keith Taylor, N. T. Misson · Electronics & Communications Engineering Journal · 1989
The results of new subjective tests on the visibility of noise in System I PAL colour television are reported. Three forms of noise are considered: white (flat) noise, de-emphasised triangular noise, and the noise resulting from vestigial sideband demodulation (VSB noise). The results are compared with those given by work published 20 years ago and it is concluded that observers today are more critical of noise in pictures: about 2½ dB less noise is required to produce the same impairment.