| 摘要 |
PURPOSE:To facilitate analysis and design by detecting a phase of an input multi-value amplitude phase modulation signal and using digital signal processing to recover the carrier thereby making the phase comparison characteristic linear. CONSTITUTION:A multi-value amplitude phase modulation signal (multivalue APSK modulation signal) inputted to an input terminal 1 is inputted to a demodulation means 2 and an input phase detection means 4 and the means 2 uses a recovered carrier from a controlled oscillation means 9 to demodulate the input multi-value APSK signal into a multi-value digital signal. The multi-value digital signal is inputted to an error voltage selection means 7 and outputted to output terminals 3a, 3b. The input phase signal outputted from the input phase detection means 4 is inputted to subtractor 5 and the subtractor 5 calculates a difference between the phase of the input phase signal and the phase of the recovered carrier being an output of the control oscillation means 9, outputs the result to an error voltage generating means 6 and the input output characteristic of the means 6 is brought into a characteristic such as a repetitive function of a pi/2 period and the phase comparison characteristic is made linear. Thus, the characteristic analysis of the phase locked loop is easily implemented and the design in matching with the request characteristic is facilitated. |
