| 摘要 |
PURPOSE:To match the phase of a reference signal at the reception side with that of a signal to be measured from a transmission system in a short time even when an error rate E is large by selecting properly a threshold value and a phase discrimination bit number. CONSTITUTION:An output of a sender side M-PN signal generator 12 is fed to a reception side input terminal 14 via a transmission system 13 to be measured and a reception signal is fed to a shift register 1, a reception side M-PN signal generator 2 and a clock recovery device 3. The M-PN signal generators 2, 12 are of the same constitution except the presence or absence of a switch 5. The recovered clock signal is fed to counters 4, 6 and added as a shift clock to the shift register 1 and the M-PN signal generator 2. Output of the shift register 1 and the M-PN signal generator 2 are fed to an exclusive OR 7. A counter 8 counts the error number of the reception signal. The error rate is calculated by an error rate counter 9 by using the outputs of the counters 8, 6, the result is fed to a phase discriminator 10 and a display device 11 and the output of the phase discriminator 10 is fed to reset terminals of the counters 4, 6 and 8.
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