| 摘要 |
PURPOSE:To avoid the mixture of the spuriousness produced in a split FM modulation recording/reproducing mode into a band of the modulated signal, by setting the carrier frequency at more than double level of the modulated signal and at the same time setting the cut-off frequency of an LPF at a specific level or less in a reproducing mode. CONSTITUTION:The carrier signal of frequency fc receives an FM modulation by the video signal to obtain the FM modulated signal S0. The signal S0 is divided into the FM modulated signal S1 which inverts its level with each rise edge and the FM modulated signal S2 which inverts its level with each fall edge. These two signals are recorded on a magnetic tape. The signal S0 is modulated so that its pedestal part is set at the carrier fc and has bands (fo-fc)-(fo+fc). At the same time, the carrier frequency fc of the recording side is set at (fc>2fo) and the cut-off frequency of an LPF of the reproducing side is set at fo. As a result, the spuriousness of fc/2 is eliminated through an LPF17. |
