PURPOSE: To improve the accuracy of signal insertion by using a transmission line switch of 2-input 1-output and matching a switching timing of the transmission line switch and a transmission timing of an insertion signal with that of a transmission line input signal automonously.
CONSTITUTION: A phase comparator 23 compares phases of change point detectors 21, 22 (that is, comparison of timewise relation between input signal Si and signal IN) to obtain a phase difference and to change an oscillating frequency of a VCO 13 via a control circuit 24. Thus, the timing of the oscillating output of the VCO 31 is automonously controlled and the oscillating output is fed to a clock input terminal CK of a D-FF 32a and a switch controller 33. The controller 33 monitors a branch signal SA being the signal Si and the signal IN and uses the oscillating output of the VCO 31 to generate a control signal S33, which applies changeover control to the transmission line switch 13 in a desired timing and the inputted insertion signal IN is sent to an output transmission line 14 in a form of an output signal So.
ODAGIRI HIDEAKI
YOSHIDA SATOSHI
Next Patent: CONNECTION DEVICE IN PARTY LINE TELEPHONE IN WIRED BOARDCAST TELEPHONE SYSTEM