Circuit arrangement for the reproduction of a magnetically stored frequency modulated signal, in particular of a television signal.

摘要

1,016,938. Local circuits for video playback heads. AMPEX CORPORATION. May 8, 1964 [July 24, 1963], No. 19241/64. Heading G5R. [Also in Division H3] The frequency response of a frequency modulated signal, e.g. a video signal, played back from a magnetic tape is corrected to a straight line amplitude/frequency characteristic with a maximum at the lower sideband limit and a minimum at the upper sideband limit, Fig. 5, shows an emphasis circuit similar to an aperture corrector employed in television circuits and designed to have an amplitude/frequency response with a maximum slightly above carrier frequency, Fig. 3 (not shown). The input is applied to an emitter follower 24 connected to a delay line 28 of which one end is connected to an amplifier 30 and the other end to an amplifier 32. The voltage at the output end of the line is constant with frequency whereas the voltage at the input varies co-sinusoidally because of the reflected signal. The amplifiers 30 and 32 are coupledto a differential amplifier 38 which feeds the output amplifier 42. Four playback heads may be coupled through amplifiers to respective emphasis circuits as shown in Fig. 5, the outputs of which pass to a head switching unit 14, Fig. 4 (not shown). The output of the switching unit passes to a head resonance compensation circuit 44 as described in Specification 1,016,939 and then to a second emphasis circuit 82 and a phase corrected low pass filter 84 feeding the demodulator 86.