Abstract
This paper deals with the evaluation of the signal to noise ratios in two typical quadraphonic FM broadcast systems, one with three transmission channels and the other with four transmission channels.
The relative noise increase, for the case of comparatively low receiver input RF signal level to which the noise output due to RF white noise is inversely proportional, is theoretically calculated and the relative audio signal level down due to correlation is measured by using quadraphonic music programmes.
As a result, relative SN ratios in quadraphonic broadcasting to the present monophonic and stereophonic broadcasting are clarified.
For example, compared to the streophonic reproduction of the present stereophonic broadcasting, the signal to noise ratio in quadraphonic reproduction is about 5 dB lower for the three-channel system, about 10 dB lower for the four-channel system and the signal to noise ratio in stereophonic reproduction is about 4 dB lower for both quadraphonic transmission systems.
