| 摘要 |
PURPOSE:To readily correspond to the alternation or a system by providing hardware servo function and software servo function. CONSTITUTION:When using a hardware servo function, a frequency error output and a phase error output are calculated by digital frequency frequency discriminating means 31 and digital phase comparing means 35 in response to timing signals S1, SS2 and Sp1,Sp2 formed by an FG signal SFG from a frequency generator 22 and a signal SPG from a phase detector 23. When using a software servo function, the means 31, 35 merely operate as free counters for counting clock pulses CK1 to obtain a frequency error output and a phase error output by a CPU 42, an ROM 43, an RAM 44 exclusive for servo. Then, the hardware servo function and the software servo function are selectively used. |
