| 摘要 |
PURPOSE:To improve the transmission quality of an auxiliary circuit by making the degree of modulation lower at a transmission side as the frequency is higher, and by newly providing a circuit, which compensates frequency characteristics, at a reception side. CONSTITUTION:In receiver 40, part of a received signal converted into an intermediate frequency is supplied from intermediate frequency amplifier 17 to four- phase phase shift demodulator 18 and reverse modulator 30. Part of the output of phase corrector 31 is supplied to the other input terminal of reverse modulator 30 by way of 90 deg. phase shifter 32. The output of reverse modulator 30 after removal of a four-phase phase shift is sent to phase comparator 33. Comparator 33 compares the phase of the input to that of the oscillation output of voltage control oscillator 34 to obtain their phase difference. This comparison output is applied to the frequency variable terminal of oscillator 34 by way of low-pass filter 35. In transmitter 29, a monitor-sessional control signal as an auxiliary circuit signal is given frequency characteristics by low-pass filter 28. |
