| 摘要 |
<p>PURPOSE:To reduce uniformly the effect of noise even on a luminance level region by FM-modulating a television picture signal via an emphasis circuit having a prescribed normalized transfer function after the amplitude of the low level of the signal is expanded. CONSTITUTION:A picture signal from a picture signal generator 1 is A/D-converted 25, this digital signal is inputted to a digital nonlinear amplitude correcting circuit 35, and after the signal amplitude of the low level part is expanded, the result is inputted to a phase linear LIP pre-emphasis circuit 12. The circuit 12 has a normalized transfer function expressed in an equation I , where tau is the unit delay time, n is a natural number, omega is an angular frequency of an input signal, and an is a coefficient and consists of plural pairs of delay elements tau, 2tau, amplitude correcting devices 53-3, 53-4 and a synthesizing device 54-2. An output of the circuit 12 is D/A-converted 45 and transmitted with FM modulation. The signal FM-demodulated is A/D-converted 26 through the reverse path at the reception side, after the signal passes through an LIP de-emphasis circuit 14, the amplitude is restored by a digital nonlinear amplitude restoring circuit 36, D/A-converted 46 and displayed 5 as a picture.</p> |
