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Browse Prior Art Database

Video Recorder with Multiplex Audio

IP.com Disclosure Number: IPCOM000089919D
Original Publication Date: 1968-Dec-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Frost, WT: AUTHOR [+4]

Abstract

In this video and audio recorder, audio head 1 records oblique tracks 2 and video head 3 records oblique tracks 4 that are parallel to tracks 2. Tracks 2 and 4 are recorded while tape 5 is held stationary. Different parts of the audio message modulate different subcarriers. The frequencies of these subcarriers increase as the recording head rotates. The recorded signal is a high-frequency carrier modulated with a waveform which is the algebraic sum of all the subcarriers of the different message parts. The terminating frequency of one subcarrier, at the completion of the recording head's revolution, is the beginning frequency of the next subcarrier as shown. In playback, the demodulated composite audio waveform is applied to a tunable filter. The bandpass of the filter is increased linearly with rotation of the audio head.

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Video Recorder with Multiplex Audio

In this video and audio recorder, audio head 1 records oblique tracks 2 and video head 3 records oblique tracks 4 that are parallel to tracks 2. Tracks 2 and 4 are recorded while tape 5 is held stationary. Different parts of the audio message modulate different subcarriers. The frequencies of these subcarriers increase as the recording head rotates. The recorded signal is a high-frequency carrier modulated with a waveform which is the algebraic sum of all the subcarriers of the different message parts. The terminating frequency of one subcarrier, at the completion of the recording head's revolution, is the beginning frequency of the next subcarrier as shown. In playback, the demodulated composite audio waveform is applied to a tunable filter. The bandpass of the filter is increased linearly with rotation of the audio head. This filter's center frequency is increased so as to track the subcarriers one at a time over successive rotations of the audio head. Thus in this system, a substantial amount of audio can be recorded on the same track and played back to correspond to a single video frame.

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