| 摘要 |
<p>1,074,264. Recording and playback. PHILIPS ELECTRONIC & ASSOCIATED INDUSTRIES Ltd. March 1, 1965 [March 4, 1964], No. 8641/65. Heading G5R. [Also in Division H3] A magnetic record/playback system for a television signal including a video signal and a frequency-modulated audio signal comprising an oscillator-modulator 4 for frequency modulating the video signal during recording, and a frequency discriminator 8 for demodulating the audio signal during recording is characterized in that, during playback, the modulator 4 remodulates the audio signal, its frequency control circuit including the discriminator 8. Recording (switches a . . . e as in Figure).- Video signals are fed from terminal 1 via amplifier 2 to the oscillator-modulator 4 and the resulting frequency-modulated signal is applied to the video head 5. Part of the modulator output is fed to a discriminator 6 to provide an a.f.c. signal which is fed via amplifier 7 back to the oscillator 4. The frequency-modulated audio signals from input 1 are fed via amplifier 3 to a discriminator 8 and the demodulated output is fed via amplifier 9 to the audio head 10. Playback (switches a . . . e in other position).- The signal from head 5 is fed via amplifier and limiter 11 to discriminator 12 to produce a video signal and output 13. The audio signal from head 10 is fed via amplifier 9 and switch b to modulator 4, and the resulting modulated output is fed via switch c to output 13. In order to control the frequency of oscillator 4 at the required audio carrier, a path is completed from output 13 via switch a to the discriminator 8 and the resulting output is applied via switch e and amplifier 7 as an a.f.c. signal for the oscillator.</p> |
