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广播电台内节目素材信号的传送是多点到多点传送为其特征的,而以多个光波复用的光分配系统较为有效。如今,日本广播协会(NHK)广播中心已经引进一种采用波分复用(Wavelength Division Multiplexing,WDM)方式的非压缩HDTV信号的光分配系统,这种系统对每一光波分配—HDTV信号,并采用光强度调制方式进行传送。 为了将来能适应台内传输系统的大容量化,设想出一种光信号复用远多于一般光强度调制的相干光传输方式。本文便对DQPSK信号的相干光接收实验进行论述。 光调制方式是用微波频段的DQPSK信号对光强度调制后,仅发送边带信号的预调制方式,其接收方式是信号光与本振光的相位无需一致的相位分集方式。 其实验结果是,当接收相当于2个非压缩HDTV信号的比特率为2.97Gb/s的DQPSK信号时,接收功率为-27dB;误码率为 10~(-11)以下,可见其特性良好。 其次,本文关于延迟检波用乘法器的输出饱和特性对误码率的影响也进行了研讨。
The transmission of program material signals in a broadcasting station is multi-point to multi-point transmission, and the light distribution system using multiple light waves is more effective. Today, the NHK Broadcasting Center has introduced an optical distribution system for uncompressed HDTV signals using Wavelength Division Multiplexing (WDM), a system that distributes HDTV signals for each light and Using light intensity modulation method for transmission. In order to adapt to the increasing capacity of the transmission system in Taiwan in the future, a coherent optical transmission method in which optical signals are multiplexed much more than the ordinary optical intensity modulation is devised. This article discusses the DQPSK signal coherent light reception experiment. The optical modulation method is a pre-modulation method that transmits only the sideband signal after modulating the intensity of light using the DQPSK signal in the microwave frequency band. The reception method is a phase diversity method in which the phases of the signal light and the local oscillation light do not need to be the same. The experimental results show that the received power is -27 dB when the DQPSK signal corresponding to 2.97 Gb / s of bit rate of two uncompressed HDTV signals is received, and the bit error rate is less than 10 ~ (-11), showing good characteristics . Secondly, this paper also discusses the effect of the output saturation characteristics of the delay detector multiplier on the bit error rate.