| 摘要 |
PURPOSE:To attain effectively rapid full duplex data transmission by executing automatic phase control in addition to automatic amplitude control for executing equal amplitude reverse phase offset and obtaining inexpensive offset effect even if the frequency of a signal is increased. CONSTITUTION:When AND operation of a signal obtained by delaying an input signal 111 inputted from an offset system to a synthesizing circuit 10 by 90 deg. and an output signal 108 of an FM demodulator 9 is calculated, a value proportional to the phase difference DELTAtheta of both the signals is obtained and the DELTAtheta is turned to zero by passing the obtained value through a control circuit 15' to control the phase shifting value of a variable phase shifting circuit 18. When AND operation between the input signal 111 to the circuit 10 and the output signal 112 from the circuit 10 is calculated, DELTAtheta 0 is formed and a value E1-E1' proportional to the size relation of the amplitude E1 of the input signal inputted to the circuit 10 and that E1' of the modulated input signal is obtained. Consequently, the amplitude difference can be turned to zero, e.g. E1=E1, by controlling the gain of a variable gain circuit 12 through the circuit 15. Thus, the negative feedback of the phase of the circuit 18 and the amplitude of the circuit 12 is controlled and a transmitting modulated signal component output from the output terminal of the circuit 10 approaches zero.
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