| 摘要 |
PURPOSE:To control a normal carrier frequency over a wide range without using a crystal oscillator by coding a carrier frequency of the normal part of a sampled FM signal, by comparing it with a coded normal carrier frequency and by controlling the level of the normal modulation part which corresponds to the comparison deviation. CONSTITUTION:This controller is equipped with separator circuit 8 which gates input FM signal (b) when receiving sampling signal (c) synchronizing with a horizontal synchronizing signal and frequency detection circuit 9 which codes the carrier frequency of the normal part of a FM signal sampled by this circuit 8. Then, digital comparator circuit 11 is provided which compares the output of circuit 9 with the coded normal carrier frequency of digital input circuit 10 so as to send out a deviation output. The output of this circuit 11 is converted by DA converter circuit 12 into an analog signal, which is applied to modulation circuit 6 via clamping circuit 5, thereby controlling the level of the normal modulation part equivalent to the comparison deviation. |
