| 摘要 |
PURPOSE:To detect the synchronization state immediately even from a signal with much noise from a demodulation circuit itself by detecting the relation of phase of a signal in phase with a clock signal inputted to a carrier recovery circuit and of a phase comparison signal from the clock recovery circuit. CONSTITUTION:A phase comparison signal G of a clock recovery circuit comprising multipliers 11,12,14, a differential amplifier 13, a loop filter 15, a VCO 16, a 1/2 frequency divider 17, an inverting circuit 18 and a latch 19 consists of a square signal and a difference signal of an in-phase component. A and an orthogonal component B obtained from an input minimum shift keying(MSK) signal subject to orthogonal detection by a carrier signal. Then a signal E in phase with a clock signal inputted to a carrier recovery circuit comprising a VCO 2, multipliers 3,4,8,9, a 90 deg.C phase shifter 5, LPFs 6,7 and a loop filter 10 and the signal G are multiplied to discriminate the synchronization state from a level of a low frequency component. Thus, synchronization is detected momentarily without a digital signal processing circuit. |
