说明：a coherent optical receiver for demodulating optical quadrature phase-shift keying (QPSK) signals. ... Third, this scheme is applicable to multilevel modulation formats such as M-array PSK and quadrature amplitude modulation (QAM). First contribution tackles the complexity of the direct detection noncoherent receiver for differentially encoded quadrature phase shift keying.

说明：取阈值是最常见的并行的直接检测区域的分割方法,很好

说明：Direct sequence spread spectrum (DSSS) communication systems has been widely used in these years for its advantage of wide spectrum, low working Signal-to-Noise ratio (SNR), anti-interference, anti-multipath effect and capability of LPI and LPD. They are increasingly replacing conventional communication forms and obtaining extensively applications in modern military and commercial communication systems, for example, CDMA communication system, GPS , measuring and control system, satellite chain, identification of friend or foe and etc. Therefore, corresponding DSSS electronic counter technique becomes a big problem to solve in electronic warfare domain. DSSS electronic counter technique including blind detection, blind parameter estimation and spreading sequences estimation. For the issue of DSSS electronic counter technique of DSSS/QPSK signal damaged by strong additive white Gaussian noise (AWGN), the main research content in this dissertation as follow.

说明：This scheme is also called DPSK since MZ modulator provides the “digital” phase modulation if it is biased at null instead of quadrature. No coherent detection is needed if data is differentially pre-coded.

说明：VPI中基于matlab联合仿真的直接检测ofdm系统

说明：研究多进制脉冲位置调制和关闭键控在直接检测光无线通信系统中存在的大气影响，比较了ook与PPM调制方式的区别。

说明：Alamouti-Type Space-Time Coding for Free-Space Optical Communication with Direct Detection

说明：OOK modulation for Radio-over-fibre system. Intensity modulation direct detection

说明：matlab的高阶谱（包括双谱），包括高阶谱的直接法及间接法，用于信号的检测及时差估计。