High signal-to-noise ratio can be achieved with the electron multiplying charge-coupled-device（EMCCD） applied in the Shack–Hartmann wavefront sensor（S–H WFS） in adaptive optics（AO）.However,when the brightness ...High signal-to-noise ratio can be achieved with the electron multiplying charge-coupled-device（EMCCD） applied in the Shack–Hartmann wavefront sensor（S–H WFS） in adaptive optics（AO）.However,when the brightness of the target changes in a large scale,the fixed electron multiplying（EM） gain will not be suited to the sensing limitation.Therefore an auto-gain-control method based on the brightness of light-spots array in S–H WFS is proposed in this paper.The control value is the average of the maximum signals of every light spot in an array,which has been demonstrated to be kept stable even under the influence of some noise and turbulence,and sensitive enough to the change of target brightness.A goal value is needed in the control process and it is predetermined based on the characters of EMCCD.Simulations and experiments have demonstrated that this auto-gain-control method is valid and robust,the sensing SNR reaches the maximum for the corresponding signal level,and especially is greatly improved for those dim targets from 6 to 4 magnitude in the visual band.展开更多
电力线信道具有噪声强、衰减大的特点,信号通过信道后变化剧烈。OFDM电力线通信系统需要有效的增益控制策略。设计了一种两级调整结构的自动增益控制(AGC,auto gain control)方法,通过采用两级环路滤波能够有效应对信号突变,保证AGC的...电力线信道具有噪声强、衰减大的特点,信号通过信道后变化剧烈。OFDM电力线通信系统需要有效的增益控制策略。设计了一种两级调整结构的自动增益控制(AGC,auto gain control)方法,通过采用两级环路滤波能够有效应对信号突变,保证AGC的收敛速度和稳定性。同时加入能量检测单元,有效降低系统待机功耗。仿真结果表明,两级调整结构的AGC具有更好的收敛特性,能够满足电力线通信的要求。展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11174274,61205021,and 61405194)the State Key Laboratory of Applied Optics,Changchun Institute of Optics,Fine Mechanics and Physics,Chinese Academy of Sciences
文摘High signal-to-noise ratio can be achieved with the electron multiplying charge-coupled-device（EMCCD） applied in the Shack–Hartmann wavefront sensor（S–H WFS） in adaptive optics（AO）.However,when the brightness of the target changes in a large scale,the fixed electron multiplying（EM） gain will not be suited to the sensing limitation.Therefore an auto-gain-control method based on the brightness of light-spots array in S–H WFS is proposed in this paper.The control value is the average of the maximum signals of every light spot in an array,which has been demonstrated to be kept stable even under the influence of some noise and turbulence,and sensitive enough to the change of target brightness.A goal value is needed in the control process and it is predetermined based on the characters of EMCCD.Simulations and experiments have demonstrated that this auto-gain-control method is valid and robust,the sensing SNR reaches the maximum for the corresponding signal level,and especially is greatly improved for those dim targets from 6 to 4 magnitude in the visual band.
文摘电力线信道具有噪声强、衰减大的特点,信号通过信道后变化剧烈。OFDM电力线通信系统需要有效的增益控制策略。设计了一种两级调整结构的自动增益控制(AGC,auto gain control)方法,通过采用两级环路滤波能够有效应对信号突变,保证AGC的收敛速度和稳定性。同时加入能量检测单元,有效降低系统待机功耗。仿真结果表明,两级调整结构的AGC具有更好的收敛特性,能够满足电力线通信的要求。
