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03607_28
DFT进行频谱分析时的三种现象
1、混叠：对连续信号采样，要求连续信号是带限的，采样频率要足够高。Fs应满足Nyquist采样定理才不产生混叠。
采样前加低通滤波器防混叠
2、频谱泄漏：DFT对时域信号进行了截断（相当于采样信号乘了一个窗函数），时域的乘积相当于频域卷积，改变了原信号频谱。
改用其他窗函数（非矩形）改善泄漏。
3、栅栏现象：DFT 只给出了频谱在采样点上的取值，采样点间的频谱内容丢失。(DFT spectrum analysis of a three phenomena, aliasing : continuous signal sampling, requiring continuous signal is band-limited, the sampling frequency should be high enough. Fs meet the Nyquist Sampling Theorem would not have aliasing. Sampling former low-pass filter plus anti-aliasing 2, spectrum leakage : DFT right time domain signal a disconnect (equivalent to a sampling signal by a window function). time domain is equivalent to the product of frequency-domain convolution, changes in the spectrum of the original signal. Window functions to switch to other (non-rectangular) to improve leakage. 3, fenced phenomenon : DFT spectrum is given only at the sampling point value, sampling points of the spectrum as lost.)
- 2007-05-08 16:22:17下载
- 积分：1
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compar
compar equivalent circuit and waveguide filter
- 2013-04-12 17:19:47下载
- 积分：1
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paper1
Transmit without regrets Online optimization in MIMO-OFDM cognitive radio systems
- 2015-02-23 19:24:19下载
- 积分：1
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ANNPID
分别采用4种控制律进行单神经元PID控制,即无监督的Hebb学习规则、有监督的Delta学习规则、有监督的Hebb学习规则、改进的Hebb学习规则.(Separately using four kinds of control laws for single neuron PID control, that is, unsupervised Hebb learning rules, there is the Delta Study supervision rules, there is supervised Hebb learning rule to improve the Hebb learning rule.)
- 2009-03-24 18:23:38下载
- 积分：1
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Modelling_Performance_of_Transmission_Lines
Modelling of electrical transmission line
- 2010-12-14 14:42:30下载
- 积分：1
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Bureau
matlab application for engeneering system
- 2011-05-24 05:37:38下载
- 积分：1
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qiefou
使用大量的有限元法求解偏微分方程，阐述了负荷预测的应用研究,采用偏最小二乘法。( Using a large number of finite element method to solve partial differential equations, It describes the application of load forecasting, Partial least squares method.)
- 2016-05-31 11:42:32下载
- 积分：1
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matlab_ray_psk
瑞利信道下空时编码下的MATLAB仿真
对两信道下的瑞利传输进行仿真(Rayleigh channel space-time coding under the MATLAB simulation)
- 2010-05-21 09:44:41下载
- 积分：1
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shannon
在数字信号的基带传输过程中，信息传输速率在满足香农公式的条件下还极大地受到码间干扰的限制(It is also limited by intersymbol interference when transmission speed of code accord with Shannon expressions in the course of baseband transmission of digital signal.)
- 2014-08-26 12:49:38下载
- 积分：1
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bpsk-ldpc
BPSK调制解调加上LDPC信道编码解码。画出误码率曲线(BPSK modulation and demodulation and LDPC channel coding and decoding. Draw the curve of error rate)
- 2014-08-27 09:17:29下载
- 积分：1
