| 摘要 |
PURPOSE:To secure the high stability of transient response by providing a function for fixing the gain of an AGC amplifier. CONSTITUTION:A gain changeover means 8 has such a function that a gain control voltage H and a fixed voltage I are inputted and either of them is sent out to the AGC amplifier 1. Then, at the time of drawing a phase, the fixed voltage I is selected to be sent out the AGC amplifier 1 by the gain control means 8. In this case, since the gain of the AGC amplifier 1 becomes constant, irrespective to any phase difference, the amplitude of a carrier signal becomes constant, regardless of the phase difference as well. As a result, an output of a phase comparator 2 against the phase difference can well be held in its linearity, so that the phase drawing operation can stably be performed. By this method, at the time of drawing the phase, a phase synchronizing operation and an amplitude equalizing operation can independently by performed respectively, thus securing the high stability of transient response. |
