基于ADC的TR-UWB数字接收机性能及其FPGA实现

发送参考超宽带(Transmitled reference UWB,TR-UWB)系统采用自相关接收检测技术作为一种非最优接收机,不需要进行信道估计和精确的时间同步,其结构简单、性能优良。数字化TR自相关接收机可以充分利用数字信号处理算法的优势,且易于用集成电路方法实现,其实现的关键是ADC。本文从理论上分析了ADC的抽样速率、量化阶数等对数字接收机的性能的影响,提出了过高阶数的量化并不能有效改善系统性能,并在FPGA上实现了TR-UWB接收机,通过编程设计与仿真,验证了基于ADC的TR-UWB接收机实现的可行性。

通信系统中自适应回波抵消的一种新方法

语音分组传输系统的出现,对回波抵消技术提出了新的挑战。在回波抵消中一个关键的问题是需要快速有效地估计延迟时间。基于直接计算输入信号互相关函数的延迟估计方法,在实际应用中回波消除性能差,运算量大。为此提出了基于混合模型的延时估计方法,对输入信号进行带通滤波和降低抽样率抽样,使其具有白噪声特性,然后快速计算互相关函数的估计值。理论分析和实验结果证明新的延迟估计方法有很好的回波消除性能和较少的运算量,在实际通信系统中有较好的应用前景。

基于分数阶Hilbert变换的多路加密

基于分数阶Hilbert变换的单边带通信可以同时将分数阶旋转角度作为加密密钥,从而保证通信安全。但基于分数阶Hilbert变换的单边带通信加密技术只能让信号使用一个加密密钥。为了达到增大密钥空间以更有效地保证信息安全的目的,采用多通道滤波器组分路处理的方法,在减少了系统计算复杂度的基础上增大了密钥空间。

导航接收机中Farrow滤波器的设计与FPGA实现

讨论了导航接收机中利用软件无线电思想进行抽样速率变换的抗混叠滤波器设计方法,给出了由此推导出的Farrow滤波器的结构图,最后利用模块化设计思想设计了一种Farrow滤波器,并在FPGA上面进行了验证。

Impact of Sampling Rate of IGS Satellite Clock on Precise Point Positioning

Both static and kinematic testings are investigated by using IGS 5rain, 30s and 5s-interval precise satellite clock prod- ucts in precise point positioning （PPP） solution. Test results show that the sampling rate oflGS satellite clock has very little effect on the static PPP solution. All the three types of sampling intervals of precise satellite clock can satisfy mm-cm level of positioning accuracy; higher sampling rate has no significant improvement for PPP solution. However, sampling rate of satellite clock has a significant impact on the PPP solution in kinematic PPP. The higher the interval of satellite clock, the better the accuracy achieved. The accuracy of kinematic PPP achieved by using 30s-interval precise satellite clock is improved by nearly 30-50 percent with re- spect to the solution by using 5min-interval precise satellite clock, but using 5s and 30s-interval satellite clock can almost produce the same accuracy of kinematic solution. Moreover, the use of precise satellite clock products from different analysis centers may also produce more or less effect on the PPP solution.