| 摘要 |
PURPOSE:To accurately calculate a value showing the characteristic of a transmission system by multiplexing a first signal having an inclining wave form part and a pulse wave form part and a second signal having the reversed wave form of the wave form of the first signal. CONSTITUTION:A test signal generator 3 generates the first signal A and the second signal B by a timing pulse. The signal A has an inclining wave form part where an instantaneous level is changed with a prescribed value at every reference period according to the sample transmission speed of an information signal and a pulse wave form part composed of a pulse to synchronize with the transmitted sample value and to be generated. The signal B has the reversed wave form of the signal A wave form. The signal A and the signal B are supplied to a multiplexing circuit 4 and multiplexed to a 605th line and a 606th line in the vertical blanking period of the output of an encoder. The output of the circuit 4 is supplied to an FM modulating circuit 5. The FM signal of the circuit 5 is supplied to an optical modulator. Thus, a value to show the characteristic of a transmission system is accurately calculated.
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