采用全球定位系统实时动态监测技术GPS-RTK(Real-Time Kinematic)和加速度计对天津富民桥进行现场动态变形监测试验。将RTK接收机的采样频率进行内部升级,由1Hz调至20Hz,并设计RTK和加速度计联合监测装置。为削弱RTK监测数据中的多路径...采用全球定位系统实时动态监测技术GPS-RTK(Real-Time Kinematic)和加速度计对天津富民桥进行现场动态变形监测试验。将RTK接收机的采样频率进行内部升级,由1Hz调至20Hz,并设计RTK和加速度计联合监测装置。为削弱RTK监测数据中的多路径误差和随机噪声影响,提出一种基于自相关函数的总体经验模态(EEMD)滤波和切比雪夫滤波相结合的混合型滤波器,称为AFEC(Autocorrelation Function based EEMD and Chebyshev)混合滤波,对RTK采集得到的数据进行滤波处理,识别出桥梁的动态位移,并与加速度数据求积分得到的位移序列进行对比,结果基本吻合,说明AFEC滤波器可以有效地削弱RTK监测数据中的多路径误差和随机噪声。展开更多
This paper describes how to use an Adaptive Forward Error Correction (AFEC) algorithm to efficiently protect the critical data areas of compressed headers and UDP-Lite packets for data transport in a radio link layer ...This paper describes how to use an Adaptive Forward Error Correction (AFEC) algorithm to efficiently protect the critical data areas of compressed headers and UDP-Lite packets for data transport in a radio link layer of a wireless connection. Augmented with RoHC and UDP-Lite, for H.264 video transmissions over wireless channels in a heterogeneous wired-wireless environment, the erroneous packet payloads can be useful and better able to cope with lost packets (native UDP case), by adopting some of the erasure and error resilient modes in H.264. The context transfer during inter/intra handover is also discussed. Simu- lations demonstrated that the proposed scenario significantly improves the PSNR performance and video quality.展开更多
Rain attenuation is the major problem for Ka-band satellite communications, and the fading due to rain can be well described by a lognormally distributed, first-order auto regressive model. Forward Error-control Codin...Rain attenuation is the major problem for Ka-band satellite communications, and the fading due to rain can be well described by a lognormally distributed, first-order auto regressive model. Forward Error-control Coding (FEC) techniques can be used to reduce the effect of the rain attenuation, but the use of FEC causes a reduction in the bandwidth efficiency.In order to increase the bandwidth efficiency as well as maintain high link availability, an Adaptive Forward Error-control Coding (AFEC) scheme with rain fading prediction is proposed and analyzed in this paper. The results show that AFEC offers a good trade-off between link availability and bandwidth efficiency.展开更多
文摘采用全球定位系统实时动态监测技术GPS-RTK(Real-Time Kinematic)和加速度计对天津富民桥进行现场动态变形监测试验。将RTK接收机的采样频率进行内部升级,由1Hz调至20Hz,并设计RTK和加速度计联合监测装置。为削弱RTK监测数据中的多路径误差和随机噪声影响,提出一种基于自相关函数的总体经验模态(EEMD)滤波和切比雪夫滤波相结合的混合型滤波器,称为AFEC(Autocorrelation Function based EEMD and Chebyshev)混合滤波,对RTK采集得到的数据进行滤波处理,识别出桥梁的动态位移,并与加速度数据求积分得到的位移序列进行对比,结果基本吻合,说明AFEC滤波器可以有效地削弱RTK监测数据中的多路径误差和随机噪声。
基金Project (Nos. FP6-IST-2003-506997 and FP6-IST-2005-026943)supported partially by the European Information Society TechnologiesFramework Programme 6 Integrated Project: "Daidalos" (European ISTProject: Daidalos, 2003~2008)
文摘This paper describes how to use an Adaptive Forward Error Correction (AFEC) algorithm to efficiently protect the critical data areas of compressed headers and UDP-Lite packets for data transport in a radio link layer of a wireless connection. Augmented with RoHC and UDP-Lite, for H.264 video transmissions over wireless channels in a heterogeneous wired-wireless environment, the erroneous packet payloads can be useful and better able to cope with lost packets (native UDP case), by adopting some of the erasure and error resilient modes in H.264. The context transfer during inter/intra handover is also discussed. Simu- lations demonstrated that the proposed scenario significantly improves the PSNR performance and video quality.
文摘Rain attenuation is the major problem for Ka-band satellite communications, and the fading due to rain can be well described by a lognormally distributed, first-order auto regressive model. Forward Error-control Coding (FEC) techniques can be used to reduce the effect of the rain attenuation, but the use of FEC causes a reduction in the bandwidth efficiency.In order to increase the bandwidth efficiency as well as maintain high link availability, an Adaptive Forward Error-control Coding (AFEC) scheme with rain fading prediction is proposed and analyzed in this paper. The results show that AFEC offers a good trade-off between link availability and bandwidth efficiency.
