| 摘要 |
PURPOSE:To facilitate a circuit constitution and to decrease the deteriorationin a reception error rate characteristic by using a signal obtained through a band limit to the output signal of a level control circuit as a demodulation output signal. CONSTITUTION:An FSK signal received by a reception antenna 10 is amplified by a high frequency amplifier 11 and inputted to a frequency mixer 12 and frequenc-converted into a base band signal. In such case, a local oscillation signal is supplied by a voltage controlled oscillator 18. The base band signal is subjected to channel band limit by a low pass filter 13. A limiter circuit 14 controls the level fluctuation in the output of the filter 13 so as to control it to a constant value. The output of the limiter circuit 14 is divided into two; the one is inputted to a negative feedback circuit to the voltage controlled oscillator 18 using a low pass filter 16 as a first stage circuit. The other signal (b) is inputted to a low pass filter 15 to obtain a demodulation signal as a signal (c), which is inputted to a binarization circuit 19 and a reception digital signal is obtained from an output terminal 195. |
