Disclosed is a method and apparatus for transmission of audio signals over
a dedicated video transmission line in which the analog audio signal is inserted
into and becomes a part of the video signal. Samples of the audio signal are inserted
into the active video line, either at the beginnings or endings, or both, of each
active video line scan signal. A defined amount of the active video interval is
reserved from the active video line, and is replaced with samples of the analog
audio signal. An analog switch in the modulator of the invention toggles to pick
up the samples of audio and place them at the designated location (either at the
beginnings or at the ends) of each active video line scan signal. A corresponding
switch in the demodulator of the invention toggles to retrieve the audio samples
from the active video line scans for output to the user. Stereo and/or bi-directional
audio signals can be transmitted by insertion into both the beginnings and the
endings of the active video line scan signals.