| 摘要 |
PROBLEM TO BE SOLVED: To suppress enlargement of device scale by shortening the time required for carrier reproduction, even in the case the deviation of a carrier frequency in hierarchical transmission occurs. SOLUTION: In a satellite digital receiver which demodulates a phase modulation signal in heirarchical transmission, carrier reproduction is performed with the C/N ratio of a phase modulation signal in a lower layer. I and Q signals, obtained by orthogonal detection of the input phase modulation signal, are converted to digital values in the constitution from an in-phase detector 2 to a since oscillator 18. These digitized I and Q signals are multiplied by the reproduced carrier to perform complex multiplication. It is discriminated by the positions of two continuous symbols in this complex multiplication signal as to whether the values of two continuous symbols match with each other to generate serial data. The B-PSK period of a heirarchical transmission phase modulation signal is settled on the basis of the detection result of frame synchronism from this serial data, and the phase modulation signal in this period is used to reproduce a carrier, and this reproduced carrier is inputted to a complex multiplier 10. |
