| 摘要 |
PURPOSE:To improve the frequency accuracy and to eliminate the need for a large sized and expensive oscillator by multiplexing the modulation signal of a fundamental wave for generating local carrier together with a modulated PCM signal, sending the result and recovering the fundamental wave having the same frequency as that at the transmission side at the reception end. CONSTITUTION:The 1st fundamental frequency to obtain each local carrier is sent together with the phase modulation signal of each PCM signal with frequency division multiplex, the result is modulated at a receiving and the 1st fundamental frequency is recovered. Even when a frequency fluctuation is caused in the 1st fundamental frequency generated by an OSC1 at a sending end, the 1st fundamental frequency having the same frequency as that at the sending end is obtained accordingly at the reception end. As a result, the frequency accuracy of an oscillator 13 generating the 1st fundamental frequency is less than a conventional system, e.g., the use of a crystal oscillator without temperature compensation is enough, an equipment is miniaturized and low-cost is attained. |
