| 摘要 |
<p>PURPOSE:To increase the processing speed by generating a square wave pulse whose frequency is swept synchronously with a coordinate transform trigger and inhibiting write of data in a logical low level to a track memory at the time when this square wave pulse exists. CONSTITUTION:Synchronously with a coordinate transform trigger 18, a VCO control circuit 14 starts the operation to generate a saw tooth wave. A VCO 13 controlled by this saw tooth wave (g) generates an FM wave whose frequency is raised in accordance with elapse of the time after the input of the trigger 18. A monostable multivibrator 12 generates a signal in the low level for a prescribed time in everyone period of this FM wave (f), and this signal is given as the voltage at a point (c). Consequently, echo suppression is accelerated toward the periphery because the frequency where the voltage at the point (c) goes to the logical low level is raised according as going from the vicinity of the center (the vicinity of the coordinate transform trigger) to the periphery. This characteristic is cancelled by the characteristic due to transformation from polar coordinates to rectangular coordinates to erase the track at a certain speed from the center to the peripheral part, and the processing speed of coordinate transformation is increased.</p> |
