| 摘要 |
PURPOSE:To obtain the detection circuit for a multi-level phase modulation signal in which relative accuracy of a multiplier, low power consumption and a complete reception waveform shaping filter are satisfied simultaneously by modulating an input digital phase modulation wave into a base band signal at a local oscillating frequency almost equal to a center frequency of the input modulation wave and waveform-shaping the signal. CONSTITUTION:A signal fed from a local oscillator 14 is inputted to frequency converters 11, 12 with a phase difference of pi/2 by a pi/2 phase difference branching device 13, an input modulation wave is frequency-converted into a base band signal, that is, subjected to orthogonal demodulation. The base band signal is inputted to low pass filters 15, 16 for shaping reception waveform, in which the signal is waveform-shaped. Then the base band signal is frequency-converted into an intermediate frequency signal by an optional local oscillation signal, and a difference between a signal resulted by sampling and holding an amplitude signal proportional to a phase of the local oscillation signal by a sampling signal generated synchronously with one period of the signal subject to frequency conversion and a signal subjected to sampling and holding for one data symbol data is subjected to multi-level processing as phase difference information. |
