| 摘要 |
PURPOSE:To attain the direct servo test and control for speed and phase systems of a VTR just through the observation of a single waveform signal, by obtaining said waveform signal through an exclusive OR addition of a reference signal and a referred signal. CONSTITUTION:In a mode III the input signal of a decoder 26 is set at H together with a speed control loop only. Under such conditions, a signal is obtained at a terminal 29 by fitting a sampling signal Sp into a head switch signal Sw. Thus it is tested to know whether or not both signals Sw and Sp have the same frequency together with their phases fixed approximately. Then the input signal of the decoder 26 is set at M to secure a mode II. In this mode II, a phase control loop is connected to a speed control loop. Then a signal Ts is obtained at the terminal 29 by fitting the signal Sp into the signal Sw. Thus it is checked whether or not the signal Sp is fixed at a prescribed phase difference against the signal Sw. While the normal disk control is carried out in a mode I . |
