DEMODULATING DEVICE FOR SSB SIGNAL

PURPOSE:To completely hold the influence of the phase noise of a local oscillator which is applied in a frequency conversion process and to increase jitter follow-up capacity by applying a pilot signal extracted from a demodulated signal to a phase comparator in a PLL without dividing the frequency of the pilot signal. CONSTITUTION:After demodulating a receiving signal by a demodulator 1, the demodulated signal is extracted as a signal through an amplifier 2. A pilot signal included in the extracted signal is extracted through a pilot extracting filter 3 and inputted to the phase comparator 51 with out dividing its frequency. The extracted pilot signal is influenced by the phase noise of the local oscillator in each conversion stage similarly to a transmission signal. On the other hand, the noise component of a pilot oscillator 7 is negligibly slight and a phase noise within a passing area of the PLL is superposed to a control voltage outputted from the phase comparator 51. When the loop band width is expanded, the phase noise is fed back to a demodulating carrier oscillator 6 and cancelled.