| 摘要 |
PURPOSE:To simplify a transmitting and receiving circuit, by providing a variable frequency oscillator for transmission and reception and by transmitting and receiving the difference between a fixed frequency or an input frequency and the variable frequency. CONSTITUTION:In case of transmission, a fixed frequency is applied from input terminal 1' to balanced modulator 3, and variable frequency-dividing oscillator 2 oscillates a frequency, which is obtained by adding the natural frequency and the transmission signal frequency, and applies this frequency to balanced modulator 3. Next, the output of balanced modulator 3 is caused to pass through low-pass filter 6 which stops passage of frequencies higher than the fixed frequency, and a frequency of the difference between the variable frequency-dividing oscillation frequency and the fixed frequency is obtained as the transmission signal output. In case of receiving, a frequency obtained by adding the receiving frequency and the center frequency of band-pass filter 4 is applied from variable frequency-dividing oscillator 2 to balanced modulator 3. When the receiving frequency is input from input terminal 1, the difference between the variable frequency-dividing oscillation frequency and the receiving frequency drops as the center frequency of band-pass filter 4 and appears at receiving output terminal 5. |
