| Summary: | 碩士 === 國立中山大學 === 光電工程學系研究所 === 98 === Coherent transmission system has been extensively studied in recent years, and it can use different modulation formats and different detection techniques. The modulation formats are ASK (Amplitude shift keying), PSK (Phase shift keying), and FSK (Frequency shift keying). The detection techniques are Homodyne detection and Heterodyne detection, and they need a laser in the receiver called as the LO (Local oscillator).
In the previous study, the BPSK (Binary phase shift keying) modulation format was investigated, and the pilot carrier method realized the Homodyne Detection. The merit of the pilot carrier is that it do not need the LO in the receiver. In this master thesis, the QPSK (Quadrature phase shift keying) modulation format is investigated using the pilot carrier method, The BER is calculated using the matlab program.
The performance of 20G bit/s, 50 km transmission system using the BPSK and the QPSK is compared to clarify the merits and demerits of the QPSK modulation.
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