| 摘要 |
PURPOSE:To keep the quality of a digital radio communication circuit normal at all times by giving phase shift of pi/2 in a moment to output phase of a voltage control oscillator included in a phase synchronizing system for carrier regeneration of a demodulation system and thereby compressing dispersion of bit error rate characteristic. CONSTITUTION:Transmitting side is provided with a D-A converter of P channel, a band restricting circuit 3, a phase modulator 6, a D-A converter of Q channel, a band restricting circuit 4, a phase modulator 7, a phase adjusting circuit 5, a carrier generating circuit 8, a pi/2 phase shiftor 9 and a composing circuit 10. Receiving side is provided with a branching circuit 11, a phase detector 12 of P channel, an A-D converter 15, a phase detector 13 of Q channel, an A-D converter 16, a clock synchronizing circuit 14, a timing controlling circuit 17, a variable phase shiftor 18, a pull-in phase discriminating circuit 19, a carrier regenerating circuit 22 including a logical circuit 20 and a voltage control oscillator 21, an oscillator to phase correction 23, an AND circuit 24, a phase correcting circuit 25, a two-phase phase modulator 26 and a pi/2 phase shiftor 27. |
