| 摘要 |
PURPOSE:To locate the center of compression around a black level, by obtaining a video signal with fidelity independently of the brightness of a screen, through the provision of a circuit having an expanding characteristic corresponding to a compressing characteristic at a recording system symmetrical to the positive and negative polarity of an expansion center level and a circuit compensating an emphasis characteristic of the recording system. CONSTITUTION:A video signal from an input terminal 1 is inputted to a preemphasis circuit 2, where high frequency components of the video signal are emphasized and a SYNC chip level is arranged at a clamp circuit 4. An output signal from the circuit 4 is applied to a compression circuit 3 consisting of resistors R1 and R2, diodes D1 and D2 and a DC voltage E1, and the compression center level of the video signal is set around the center of the black level set at the voltage E1. This compressed video signal is recorded on a magnetic tape via an FM modulator 5 and demodulated at an FM demodulator 8. The demodulated signal is expanded with an expanding circuit 9 having the same characteristic as the compressing characteristic of the circuit 3, the compression center level and the expansion center level are coincident, and a video signal with high fidelity can be outputted from a deemphasis circuit 10. |
