PROCESS AND APPARATUS FOR MEASURING THE CARRIER/NOISE RATIO IN A TELEVISION CHANNEL

摘要

The object is to reduce considerably the volume and cost of the apparatus. The video carrier is measured by using a detector of the maximum level of carrier (6), said detector being connected to a microprocessor (10) which causes the tuner (VHF/UHF) (2) to displace the tuning of the channel to an intermediary zone between the video carrier and the audio carrier, recalculating and acting subsequently on the status of the input attenuators as a function of the carrier level. The microprocessor (10) is also connected to a rapid detector (7) of the noise level for which it changes to this detector level, storing the minimum noise value, thereby obtaining the carrier/noise ratio. The process is repeated for each image, so that one of the measured values of the noise level will surely fall within the zone wherein there is practically no carrier influence, thereby obtaining a reliable final measurement to evaluate the image quality.