| 摘要 |
PURPOSE:To follow the sudden frequency-transition of an input signal by converting the difference between stored center frequency and the frequency of the input signal into a DC bias value and controlling a local oscillator by a signal obtained by adding said DC bias value to a phase difference signal integrating output. CONSTITUTION:A signal inputted from a terminal 10 is sampled and inputted to a phase synchronization part B through a signal system storing means 1. The sampled input signal is also stored in a signal system storing means 1 for a fixed period, the frequency of said period is calculated and compared 2 with the center frequency stored in an average frequency storing means 3 and the compared output is converted into a DC value by a D/A converter 5 through a DC bias storing means 4. The output of the D/A converter 5 is added to a signal from the phase difference signal integrating means 7 by a DC bias adding means 8 in the phase synchronization part B and the added output controls the local oscillation means 9. Thus, the transient time for the sudden frequency variation of the input signal is shortened. |
