| 摘要 |
PURPOSE:To detect a code error at a high speed by solving astable operation at a DC level of a circuit which exercises supervision over the circuit quality of a digital signal transmission line, by forming this circuit of simple constitution. CONSTITUTION:An input signal is applied to phase detectors 1 and 2; detector 1 is applied with a signal obtaind by phase-shifting a reference carrier by pi/2 by pi/2- phase shifter 3, and detector 2 with the reference carrier to output signals bearing an orthogonal phase relation from detectors 1 and 2. Then, those signals are inputted to discriminators 4 and 6, which output digital signals CH1 and CH2 discriminated and waveform-shaped. Further, an input signal is applied to phase detector 8, which is applied with the reference carrier phase-shifted by DELTAtheta by phase shifter 9 to apply its output to discriminator 10, which generates a signal forced to increase code errors. Then, this signal is applied to exclusive-OR circuit 7 together with the signal discriminated by discriminator 6 to generate a code error signal. Then, variation in the DC level of a circuit generating signals CH1 and CH2 is prevented to detect the code error. |
