Digital interpolation beamforming is feasible . by using it , the result as same as by using high sampling rate can be got after passing a interpolation filter with the premise that nyquist sampling theorem should be satisfied and the frequence response of the filter is good enough 数字内插波束形成技术是一种可行的方法，它能够在低的采样率下，通过内插滤波，获得与高速采样相同的结果，前提是满足奈奎斯特采样定律和内插滤波器的频率响应足够好。
According to the nyquist first criterion , the usual way is to use raising cosine shaping filter in real communication system . by choosing appropriate rolling off factor and determining the distribution of its characteristics between the transmitter and the receiver , the shaping , filter will minimize the nonlinear distortion , of channel 根据奈奎斯特第一准则，在实际的通信系统中，通常的途径是采用升余弦滚降成形滤波器，选择适当的滚降系数，并确定其特性在收、发两端的分配问题，以便将信道非线性的影响最小化。
Chapter 3 discusses the modules used in the fh - mpsk and fh - / 4dqpsk systems . these modules include : duc / ddc ( digital up converter / digital down converter ) , nyquist flitter , burst start detection , interpolation module , pll ( phase locked loop ) , pll error extraction , initial phase correction and the coding and decoding for tcm 第三章主要讨论了跳频模式下fh - mpsk和fh - 4dqpsk系统中各个模块的设计，这些模块包括：上下变频器、奈奎斯特滤波器、信号到达检测、插值模块、通用环路、各环路误差提取方法、初始相位校正和tcm编译码。
The proposed modulator uses 0 . 35um standard cmos process , the nmos and pmos threshold voltage is 0 . 54 volt and - 0 . 48 volt , respectively , and the power supply is 1 . 5 volt . the nyquist converter rate is 50 khz , oversampling ratio is 80 . the proposed modulator can obtain 98db dynamic range , 16 bits converter resolution , and fits for high - fidelity , digital - audio application 本设计采用0 . 35微米标准cmos工艺,其中nmos和pmos晶体管的阈值电压分别为0 . 54伏和- 0 . 48伏,电源电压为1 . 5伏,奈奎斯特转换率为50khz ,过采样率为80 ,该调制器可实现动态范围98db , 16位的转换精度,适合高保真数字音频应用。
This thesis begins with hfc network theory and docsis , analyses modulation / demodulation process of data communication in hfc . then , several theories are analysed including qam ( quadrature amplitude modulation ) , nyquist root square filter , fec ( forward error correction ) , map ( bandwidth allocation map ) . and digital signal transmission involved the other important international standard ? itu - t j . 83 annex a / b , is discussed 本文从hfc网络理论和docsis协议入手，分析了hfc数据通信的调制解调过程，对qam调制、奈奎斯特均方根滤波器、前向纠错（ forwarderrorcorrection ，简称fec ） 、 map通信等进行了阐述；还从中探讨了电缆调制解调器需要用到的另一个国际标准ituj . 83annexa / b所设计的mpeg信号的数字传输。
( 2 ) the characters of the signal for the low voltage electrophoresis chip , signal processing theory such as the nyquist theory , fft , fir filter and the wavelet have been discussed after the learning of low voltage electrophoresis theory and the analyzing of the low voltage electrophoresis chip 2在深入了解重庆大学微系统研究中心研制的低电压分离电泳芯片结构、原理、信号检测方式的基础上，分析了毛细管电泳芯片信号特点以及相关的数字信号处理方法（奈奎斯特抽样定理、傅立叶变换、有限长单位冲激响应（ fir ）滤波器、小波变换） 。
At first , the average - current controlled boost pfc and buck converter small - signal model are estabished . the average - current controlled boost pfc and buck converter prototype are designed and manufactured . on basis of the small - signal model , the two - stage i / o impedance characteristic and miller effect are analyzed by simulation with matlab software 其次单独设计了前级、后级变换器样机，在两级模型基础上，应用matlab软件仿真分析了前后级变换器对接处的i o阻抗特性和密勒效应，运用奈奎斯特判据对两级结构宽输出电压范围的功率因数校正器的稳定性进行了分析设计。
On the basis of the former research works , we present the detecting method as follows : for the narrow band characteristic of the track signal we use under - sampling instead of nyquist sampling to reduce the sampling rate . as to the carrier frequency , the spectrum of the 18 - information frequency - shift track signal has two peaks , then the carrier frequency is the average of the two peak frequency , to um - 71 jointless track signal , it has only one peak , then the carrier frequency is the peak frequency 针对移频轨道信号的窄带特性提出了使用欠采样技术代替奈奎斯特采样的方法,以降低信号的采样频率;国产18信息移频轨道信号频谱具有双峰,双峰频率平均值就是信号的载频频率,而um - 71无绝缘轨道信号频谱单峰,峰值频率即为信号的载频频率。
Under the condition of one pixel image motion , adopting the modulation method , the ratios of the mtf with image motion to the idea mtf are 0 . 591 . the difference amount of mtf is shown . they are analyzed that the types of optic system , obstructive ratio influence the mtf and the methods improvement the imaging resolution of remote sensing camera 在存在一个像元的像移量时在奈奎斯特频率处，卷积法的有像移的mtf值和理想的mtf值之比为0 . 591 ，仿真法在存在一个像元的像移量时，有像移的mtf值和理想的mtf值之比为0 . 667 ，从中看到了两者之间定量的差异。
