| 摘要 |
PURPOSE:To eliminate the noise in a DC/DC converter and to stabilize the operation of a PCM transmitte, by using a main clock of the PCM transmitter after frequency-division for a power supply clock. CONSTITUTION:A sound signal S is inputted from an input terminal 4 of a PCM transmitter 3, processed at the transmitter 3 and transmitted to a transmission terminal 10, and a signal from a reception terminal 11 is processed at the transmitter 3 and applied to a spectrum analyzer 21. An output line 19' of a clock 19 of a power supply device 16 of the transmitter 3 is disconnected, the driving of a DC/DC converter 18 is stopped with the clock 19, and a main clock 22 of the transmitter 3 is used as a clock used for the converter 18. The main clock 22 is frequency-divided into a prescribed frequency corresponding to a multiple of a channel band frequency at a frequency divider 23, the output of the frequency divider 23 drives the converter 18, the DC output of the converter 18 is applied to the transmitter 3 via a power supply line 17, the noise by the converter 18 is eliminated, and the operation of the transmitter 3 is made stable. |
