| 摘要 |
PURPOSE:To adjust a DC voltage supply circuit including gain variations of an encoding circuit, a BPF, a decoding circuit in a direct current voltage supply circuit, and an LPF by adjusting the value of a DC voltage to the decoder while observing the output of the decoder and adjusting the value of a DC voltage to the encoder while observing the output of the encoder. CONSTITUTION:The 1st digital signal train is inputted from a digital signal train input terminal 20 and the value of the DC supply voltage impressed to the decoder through a supply line 10 is adjusted by using an adjusting circuit included in a DC voltage supply circuit 3 while an analog signal observation terminal 15 is observed. Then, the 2nd digital signal train is impressed to the digital signal train input terminal 10 and the analog output signal of the decoder is impressed from the output terminal 14 of the decoder 4 to the input terminal 7 of the encoder 2 through a short-circuit line 16. The analog signal of the decoder is encoded by the encoder 2 and outputted from an output terminal 8 to a digital signal observation terminal 17. The value of the DC supply voltage is corrected with the gain of the decoder 4 measured during the gain adjustment of the encoder 2 and adjusted while the encoding circuit and BPF are observed, thereby improving the gain adjustment accuracy of the encoder 2.
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