| 摘要 |
PURPOSE:To take properly a measure avoiding degradation by using a discrimination decision circuit of a demodulated signal, an absolute value device, a divider, real number and imaginary number square-law averaging circuits, etc., to detect and display distinctively the degradation of the quality of a received signal due to the noise of a transmission line and a phase jitter. CONSTITUTION:A multiplier 2 multiplies the input of a discrimination decision circuit 1 and a complex conjugate number of an output sample, and an absolute value device 3 operates the absolute value of the output sample, and the output of the multiplier 2 is divided in a divider 4 by the absolute value of the output sample. One is subtracted from the output of square-law averaging circuits 5 and 6 of a real part of the output of the divider 4 by a subtractor 7, and the output of a sqaure-law averaging circuits 8 and 9 of an imaginary part is added 10 to the output of the substractor 7, and the result is sent to a comparator 11. This comparator 11 lights a noise display lamp 12 if the output of an adder 10 is larger than a constant K1. The output of the subtractor 7 and a constant K2 are multiplied by a multiplier 13, and the output of the multiplier 13 and the output of the averaging circuit 9 are compared with each other by a comparator 14, and a phase jitter lamp 15 is lit if the former is smaller than the latter. |
