interpolation_filter.m

插值滤波器

function [ Sample_Synchronous_Period ] = Interpolation_Filter(Sample_Independence_Period)
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% Interpolation_Filter.m 
% 函数文件 
% 拉格郎日立方插值滤波器
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%==========================================================================
%输入接口参数：Sample_Independence_Period(独立时钟采样序列)
%输出数据： Sample_Synchronous_Period（同步后采样序列）
%独立采样周期：Independence_Period
%同步后采样周期：Synchronous_Period
%符号周期：Symbol_Period
%定时误差：Timing_Error
%分数间隔：Fractionally_Space
%基本指针：Baseic_Pointer
%参与插值的样值：Interpolation_Sample
%插值滤波器系数：Interpolated_Coefficients
%==========================================================================


global Independence_Period;
global Synchronous_Period;
global Symbol_Period ;


Symbol_Period =1/(28*10^9);
Independence_Period = Symbol_Period/4;
Synchronous_Period = Symbol_Period/1;

% Sample_Independence_Period = csvread('trans_delay_polx_I.csv', 7, 1);
Resample_Number=length(Sample_Independence_Period)/4*1;                      
Timing_Error = 0;

for k=2:1:Resample_Number-1
Add(k) = (k*Synchronous_Period + Timing_Error*Symbol_Period) / Independence_Period;
Fractionally_Space(k) = mod(Add(k),1);
Baseic_Pointer(k) = Add(k) - Fractionally_Space(k) ;
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%拉格郎日插值滤波器，每次选四个样值进行插值
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Interpolation_Sample1 = Sample_Independence_Period(Baseic_Pointer(k)+2);
Interpolation_Sample2 = Sample_Independence_Period(Baseic_Pointer(k)+1);
Interpolation_Sample3 = Sample_Independence_Period(Baseic_Pointer(k));
Interpolation_Sample4 = Sample_Independence_Period(Baseic_Pointer(k)-1);

Interpolated_Coefficients1 = 1/6*(Fractionally_Space(k)^3 - Fractionally_Space(k));
Interpolated_Coefficients2 = 1/2*Fractionally_Space(k)^2 - 1/2*Fractionally_Space(k)^3 + Fractionally_Space(k);
Interpolated_Coefficients3 = 1/2*Fractionally_Space(k)^3 - Fractionally_Space(k)^2 - 1/2*Fractionally_Space(k) + 1;
Interpolated_Coefficients4 = 1/2*Fractionally_Space(k)^2 - 1/6*Fractionally_Space(k)^3 - 1/3*Fractionally_Space(k);

Sample_Synchronous_Period(k) =  Interpolation_Sample1*Interpolated_Coefficients1 + Interpolation_Sample2*Interpolated_Coefficients2 + Interpolation_Sample3*Interpolated_Coefficients3 + Interpolation_Sample4*Interpolated_Coefficients4;
end
Sample_Synchronous_Period;