High resolution video signals of bandwidth up to 25 mHz are recorded magnetically or optically, or are transmitted on a communications channel carrier with superior fidelity by using novel electronic circuit system including implementations of an FM modulator, writing amplifier, and wideband discriminator...http://www.google.fr/patents/US4435734?utm_source=gb-gplus-shareBrevet US4435734 - FM Video recording and reproducing system
