A video and audio signal recording apparatus includes a first frequency modulator in which a first audio signal to be recorded that may represent a stereophonic left channel modulates a first carrier to produce a first FM audio signal, and a first frequency convertor converts the carrier frequency of...http://www.google.es/patents/US4580174?utm_source=gb-gplus-sharePatente US4580174 - Apparatus for recording and/or reproducing video and audio signals
Apparatus for recording and/or reproducing video and audio signals
