This paper deals with the technology of using comb filters for FIR Decimation in Digital Signal Processing. The process of decreasing the sampling frequency of a sampled signal is called decimation. In the usage of de...This paper deals with the technology of using comb filters for FIR Decimation in Digital Signal Processing. The process of decreasing the sampling frequency of a sampled signal is called decimation. In the usage of decimating filters, only a portion of the out-of-pass band frequencies turns into the pass band, in systems wherein different parts operate at different sample rates. A filter design, tuned to the aliasing frequencies all of which can otherwise steal into the pass band, not only provides multiple stop bands but also exhibits computational efficiency and performance superiority over the single stop band design. These filters are referred to as multiband designs in the family of FIR filters. The other two special versions of FIR filter designs are Halfband and Comb filter designs, both of which are particularly useful for reducing the computational requirements in multirate designs. The proposed method of using Comb FIR decimation procedure is not only efficient but also opens up a new vista of simplicity and elegancy to compute Multiplications per Second (MPS) and Additions per Second (APS) for the desired filter over and above the half band designs.展开更多
多波段信号融合技术在信号层将多个不同子带融合成一个大带宽信号,因而能够有效提高雷达图像距离分辨率。目前,基于全极点模型的融合技术主要采用root-MUSIC(multiple signal classification)及其改进算法实现极点的估计,在较弱的噪声...多波段信号融合技术在信号层将多个不同子带融合成一个大带宽信号,因而能够有效提高雷达图像距离分辨率。目前,基于全极点模型的融合技术主要采用root-MUSIC(multiple signal classification)及其改进算法实现极点的估计,在较弱的噪声条件下这种方法得到了不错的融合效果。然而在低信噪比条件下root-MUSIC算法容易受到噪声干扰而难以实现正确极点获取,进而极大影响到最终信号融合效果。为减小噪声影响,提出用矩阵束算法实现多波段信号极点估计,在此基础上通过不同子带对应极点间的相位关系估计出相干参数,同时对融合结果以信号差的2范数最小为准则进行迭代,以减小融合信号的误差。最后采用加权寻优的方式进一步提高了信号的融合精度。仿真实验结果表明,提出的方法有效提高了低信噪比条件下的多波段信号融合效果。展开更多
The single sideband （SSB） modulation is assessed as a means to mitigate the dispersion-induced power fading on the distribution of ortogonal frequency division multiplexing （OFDM） ultra wideband （UWB） radio sign...The single sideband （SSB） modulation is assessed as a means to mitigate the dispersion-induced power fading on the distribution of ortogonal frequency division multiplexing （OFDM） ultra wideband （UWB） radio signals along long-reach passive optical networks （LR-PONs）. Particularly, two different SSB ar- chitectures, namely, Sieben＇s architecture and four phase modulator （FPM） architecture are optimized to provide maximum sideband suppression. The minimum optical signal-to-noise ratio （OSNR） required to simultaneously distribute all the 14 OFDM-UWB sub-bands along the LR-PON distances ranging between 80 and 100 km is also evaluated through numerical simulation. FPM architecture is preferable over Sieben＇s architecture because the latter SSB architecture generates carriers-carriers beat term at the photodetector output with high power, thereby causing significant degradation in the OFDM-UWB sub-bands with lower central frequencies. The simultaneous distribution of the 14 SSB OFDM-UWB sub-bands in the LR-PON using the FPM architecture shows a minimum OSNR penalty of 3 dB compared with the centralized dis- persion compensation technique.展开更多
文摘This paper deals with the technology of using comb filters for FIR Decimation in Digital Signal Processing. The process of decreasing the sampling frequency of a sampled signal is called decimation. In the usage of decimating filters, only a portion of the out-of-pass band frequencies turns into the pass band, in systems wherein different parts operate at different sample rates. A filter design, tuned to the aliasing frequencies all of which can otherwise steal into the pass band, not only provides multiple stop bands but also exhibits computational efficiency and performance superiority over the single stop band design. These filters are referred to as multiband designs in the family of FIR filters. The other two special versions of FIR filter designs are Halfband and Comb filter designs, both of which are particularly useful for reducing the computational requirements in multirate designs. The proposed method of using Comb FIR decimation procedure is not only efficient but also opens up a new vista of simplicity and elegancy to compute Multiplications per Second (MPS) and Additions per Second (APS) for the desired filter over and above the half band designs.
文摘多波段信号融合技术在信号层将多个不同子带融合成一个大带宽信号,因而能够有效提高雷达图像距离分辨率。目前,基于全极点模型的融合技术主要采用root-MUSIC(multiple signal classification)及其改进算法实现极点的估计,在较弱的噪声条件下这种方法得到了不错的融合效果。然而在低信噪比条件下root-MUSIC算法容易受到噪声干扰而难以实现正确极点获取,进而极大影响到最终信号融合效果。为减小噪声影响,提出用矩阵束算法实现多波段信号极点估计,在此基础上通过不同子带对应极点间的相位关系估计出相干参数,同时对融合结果以信号差的2范数最小为准则进行迭代,以减小融合信号的误差。最后采用加权寻优的方式进一步提高了信号的融合精度。仿真实验结果表明,提出的方法有效提高了低信噪比条件下的多波段信号融合效果。
基金supported by Fundacao para a Cienciae a Tecnologia from Portugal under contract SFRH/BD/29871/2006 the project TURBO-PTDC/EEA-TEL/104358/2008supported in part by the European FIVER-FP7-ICT-2009-4-249142 project
文摘The single sideband （SSB） modulation is assessed as a means to mitigate the dispersion-induced power fading on the distribution of ortogonal frequency division multiplexing （OFDM） ultra wideband （UWB） radio signals along long-reach passive optical networks （LR-PONs）. Particularly, two different SSB ar- chitectures, namely, Sieben＇s architecture and four phase modulator （FPM） architecture are optimized to provide maximum sideband suppression. The minimum optical signal-to-noise ratio （OSNR） required to simultaneously distribute all the 14 OFDM-UWB sub-bands along the LR-PON distances ranging between 80 and 100 km is also evaluated through numerical simulation. FPM architecture is preferable over Sieben＇s architecture because the latter SSB architecture generates carriers-carriers beat term at the photodetector output with high power, thereby causing significant degradation in the OFDM-UWB sub-bands with lower central frequencies. The simultaneous distribution of the 14 SSB OFDM-UWB sub-bands in the LR-PON using the FPM architecture shows a minimum OSNR penalty of 3 dB compared with the centralized dis- persion compensation technique.
