| 摘要 |
PROBLEM TO BE SOLVED: To measure the CN ratio even for a digital modulated signal used for BS digital broadcasting. SOLUTION: The CN ratio of the digital modulated signal is computed by making a control arithmetic circuit 13 performed operations shown by equations (22) to (26) based on the power value 'Pa' of the digital modulated signal corresponding to a digital receive signal inputted to an input terminal 2, the power value 'Pb' of the digital modulated signal obtained by adding noise to the digital modulated signal corresponding to the digital receive signal inputted to the input terminal 2, and the error rate 'b' of a demodulated signal obtained by demodulating the digital modulated signal. Here, (22) p=Pa/(Pb-Pa), (23) q=Ber-1(b), (24) p=q, (25) C/N=∞, and (26) C/N=q(1+p)/(p-q). |
