| 摘要 |
PURPOSE:To remove a crosstalk noise effectively by using two nonlinear empha sis circuits. CONSTITUTION:A pre-emphasis circuit 12 and a compressing circuit 13 constitute a nonlinear pre-emphasis cicuit and are provided in consideration of the point that the degree of improvement of an SN ratio during FM modulation is smaller and smaller as a modulation frequency is higher and higher. Further, a compressing circuit 13 does not limit a signal level merely, so there is no dam age of a waveform caused and a video signal to be frequency-modulated is put within a transmission band. A pre-emphasis circuit 14 has a larger time constant and a smaller quantity of emphasis than the pre-emphasis circuit 12 by selecting values of resistors 43 and 45 and a capacitor 44; and the pre- emphasis circuit 12 and compressing circuit 13 constitute a nonlinear pre- emphasis circuit for noise removal and pre-emphasis circuits 14 and 15 and a compressing circuit 11 constitute a nonlinear pre-emphasis circuit for crosstalk noise removal. |
