| 摘要 |
PURPOSE:To realize the pilot rejection without lowering the quality of the transmission line signal by connecting the rejector featuring the necessary rejection properties between the modulators which are driven by the carrier of the common frequency as the means which detects the transmission line monitor pilot. CONSTITUTION:Crystal rejector 6 is connected between modulators 4 and 7 which are driven by the common carrier in order to reject the transmission line monitor pilot in the frequency multiple transmission system featuring the transmission frequency possessing both the lower and upper limit frequencies. The transmission signal sent from input terminal 1 is applied to the input of modulator 4, and the output of modulator 4 is applied to band pass filter 5 in which the lower side band is set to the pass band. And the output of filter 5 is applied to rejector 6, and this rejector produces the frequency of the higher harmonic tone which is 3 or 5 times as high as the basic frequency of the crystal oscillator to block the transmission line monitor pilot. Then the output is applied to modulator 7, and thus the signal with the pilot rejected is delivered from the output of modulator 7 without lowering the quality of the transmission signal. |
