To estimate the angle of arrivals （AOA） of wideband chirp sources, a new timo-frequency algorithm is proposed. In this method, virtual sensors are constructed based on the fact that the steering vectors of wideband ...To estimate the angle of arrivals （AOA） of wideband chirp sources, a new timo-frequency algorithm is proposed. In this method, virtual sensors are constructed based on the fact that the steering vectors of wideband chirp signals are linear and vary with time. And the randon Wignersville distribution （RWVD） of real sensors and virtual sensors are calculated to yield the new time-invariable steering vectors, furthermore, the noise and cross terms are suppressed. In addition, the multiple chirp signals are selected by their time-frequency points. The cost of computation is lower than the common AOA estimation methods of wideband sources due to nonrequirement of frequency focusing, interpolating and matrix decomposition, including subspace decomposition. Under the lower signal noise ratio （SNR） condition, the proposed method exhibits better precision than the method of frequency focusing （FF）. The proposed method can be further applied to nonuniform linear array （NLA） since it is not confined to the array geometry. Simulation results illustrate the efficacy of the proposed method.展开更多
The realization of the parameter estimation of chirp signals using the fractional Fourier transform (FRFT) is based on the assumption that the sampling duration of practical observed signals would be equal to the time...The realization of the parameter estimation of chirp signals using the fractional Fourier transform (FRFT) is based on the assumption that the sampling duration of practical observed signals would be equal to the time duration of chirp signals contained in the former. However, in many actual circumstances, this assumption seems unreasonable. On the basis of analyzing the practical signal form, this paper derives the estimation error of the existing parameter estimation method and then proposes a novel and universal parameter estimation algorithm. Furthermore, the proposed algorithm is developed which allows the estimation of the practical observed Gaussian windowed chirp signal. Simulation results show that the new algorithm works well.展开更多
针对超短波信道快衰落、远近效应、多径效应等特点,针对现有渔船超短波通信系统噪声高、通信距离下降的问题,提出一种适用于渔船超短波通信系统的前端功率控制算法:利用双chirp前导信号实现发送端信号功率控制和接收端自动增益控制,先...针对超短波信道快衰落、远近效应、多径效应等特点,针对现有渔船超短波通信系统噪声高、通信距离下降的问题,提出一种适用于渔船超短波通信系统的前端功率控制算法:利用双chirp前导信号实现发送端信号功率控制和接收端自动增益控制,先通过一次检测chirp波相关峰值,获得信道的增益初估计,反馈调整AD前端的自动增益放大器,使信号达到合适的处理增益;通过检测第2个chirp波相关峰值,获得第2次增益估计;最后通过AR模型实现增益的精确估计与调整。仿真结果表明,该算法对接收端可以实现40 d B以上的增益调整,发送端可以节省30%以上的功耗。该算法的应用,可以降低超短波信道的背景噪声,改善渔业超短波信道环境,网络性能可得到提高。展开更多
文摘To estimate the angle of arrivals （AOA） of wideband chirp sources, a new timo-frequency algorithm is proposed. In this method, virtual sensors are constructed based on the fact that the steering vectors of wideband chirp signals are linear and vary with time. And the randon Wignersville distribution （RWVD） of real sensors and virtual sensors are calculated to yield the new time-invariable steering vectors, furthermore, the noise and cross terms are suppressed. In addition, the multiple chirp signals are selected by their time-frequency points. The cost of computation is lower than the common AOA estimation methods of wideband sources due to nonrequirement of frequency focusing, interpolating and matrix decomposition, including subspace decomposition. Under the lower signal noise ratio （SNR） condition, the proposed method exhibits better precision than the method of frequency focusing （FF）. The proposed method can be further applied to nonuniform linear array （NLA） since it is not confined to the array geometry. Simulation results illustrate the efficacy of the proposed method.
基金supported by the National Natural Science Foundation of China (60872003 61071214)+1 种基金the Doctoral Fund of Ministry of Education of China (20093201110005)the Foundation of Chinese National Defense Technology Key Laboratory (9140C1301031001)
文摘The realization of the parameter estimation of chirp signals using the fractional Fourier transform (FRFT) is based on the assumption that the sampling duration of practical observed signals would be equal to the time duration of chirp signals contained in the former. However, in many actual circumstances, this assumption seems unreasonable. On the basis of analyzing the practical signal form, this paper derives the estimation error of the existing parameter estimation method and then proposes a novel and universal parameter estimation algorithm. Furthermore, the proposed algorithm is developed which allows the estimation of the practical observed Gaussian windowed chirp signal. Simulation results show that the new algorithm works well.
文摘针对超短波信道快衰落、远近效应、多径效应等特点,针对现有渔船超短波通信系统噪声高、通信距离下降的问题,提出一种适用于渔船超短波通信系统的前端功率控制算法:利用双chirp前导信号实现发送端信号功率控制和接收端自动增益控制,先通过一次检测chirp波相关峰值,获得信道的增益初估计,反馈调整AD前端的自动增益放大器,使信号达到合适的处理增益;通过检测第2个chirp波相关峰值,获得第2次增益估计;最后通过AR模型实现增益的精确估计与调整。仿真结果表明,该算法对接收端可以实现40 d B以上的增益调整,发送端可以节省30%以上的功耗。该算法的应用,可以降低超短波信道的背景噪声,改善渔业超短波信道环境,网络性能可得到提高。
