| 摘要 |
PURPOSE:To execute a satisfactory demodulation, by preventing the jitters of the carrier wave, in case of 16QAM modulation. CONSTITUTION:As a control signal of a voltage control oscillator VCO for regenerating a carrier wave in the receiving side, an output S3 of a subtracter 48 is used. When base band signals of amplitude 1, 0.5 are made u1, u2, v1, v2, and those which have been discriminated are made u1', u2', v1', v2', in case they are discriminated correctly, S3=-(u1' u1+u1' v1+u2' u2+u2' v2) sinthetae+(u2' v1-u1' v2)(costhetae-1)(thetae is a phase error). In case when control is executed almost correctly, thetae 0. Accordingly, costhetae=1, said expression becomes only the first term relating to sinthetae, and the second term of the right side contributing to the jitters is eliminated. |
