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%程序功能：QPSK信號解調??2018.03.29?????????????%
%程序流程：碼元同步?載波同步?判決輸出????????????%
%要????求：采樣率為碼元速率的整數倍??????????????%
%問????題：由于未考慮加納算法首尾問題可能產生誤判（例如加納算法該次XX在0附近?而下次再Rate附近）
%該程序僅做原理說明?還有許多不足?需要完善
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clc;
close?all;
clear?all;

%信號基本參數
Fs??=?32e6;?????????%信號采樣率
Fb??=?0.5e6;????????%碼元速率?
Fc??=?3e6;??????????%實際載波頻率
ts??=?1/Fs;?????????%時間分辨率?
wfc?=?Fc+2000;??????%初始頻率
Rate?=?Fs/Fb;???????%每個碼元樣點個數?
num?=?1e5;??????????%樣點個數

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%生成QPSK信號%%%%%%%%%%%%%%%%%%%%%%%%%%%%


%%%%%帶通濾波器設計%%%%
Fstop1?=?Fc-Fb-0.25e6;????????????%?First?Stopband?Frequency
Fpass1?=?Fc-Fb;????????????%?First?Passband?Frequency
Fpass2?=?Fc+Fb;????????????%?Second?Passband?Frequency
Fstop2?=?Fc+Fb+0.25e6;????????????%?Second?Stopband?Frequency
Dstop1?=?0.0001;??????????%?First?Stopband?Attenuation
Dpass??=?0.057501127785;??%?Passband?Ripple
Dstop2?=?0.0001;??????????%?Second?Stopband?Attenuation
dens???=?20;??????????????%?Density?Factor
%?Calculate?the?order?from?the?parameters?using?FIRPMORD.
[N?Fo?Ao?W]?=?firpmord（[Fstop1?Fpass1?Fpass2?Fstop2]/（Fs/2）?[0?1?...
??????????????????????????0]?[Dstop1?Dpass?Dstop2]）;
bfir1??=?firpm（N?Fo?Ao?W?{dens}）;

disp（‘生成QPSK信號‘）;
%產生QPSK信號
LData?=?ceil（num/Rate）;????????%碼元數量
Symbs?=?zeros（LData1）;??
for?i=1:1:LData
????Symbs（i）?=?randi（41）;???%隨機產生符號
end

constellation_map=[0?0.5*pi?pi?1.5*pi];??????%星座圖
Pskmodu?=?constellation_map（Symbs）;??????????%映射
angl?=?zeros（num1）;?????????????????????????%對應
for?i=1:1:num????
???angl（i）?=?Pskmodu（floor（（i-1）/Rate）+1）;????
end

SNR?=?-20;????????????????????????????????????%信噪比

BPSK_Sig?=?zeros（1num）;??????????????????????
for?k=1:1:num
????BPSK_Sig（k）?=?（cos（2*pi*Fc*k*ts+angl（k））+sqrt（10^（SNR/10））*randn（11））;?%%產生信號并加噪聲
end
Data?=?conv（BPSK_Sigbfir1）;?????????????????????????????????????????????????????%帶通濾波

if（num>length（Data））
????num?=?length（Data）;????%判斷是否超過數據長度?若超過則num等于數據長度
end

%低通濾波器設計
Fpass?=?0.5e6;???????????%?Passband?Frequency?
Fstop?=?2e6;?????????????%?Stopband?Frequency
Dpass?=?0.057501127785;??%?Passband?Ripple
Dstop?=?0.0001;??????????%?Stopband?Attenuation
dens??=?20;??????????????%?Density?Factor
%?Calculate?the?order?from?the?parameters?using?FIRPMORD.
[N?Fo?Ao?W]?=?firpmord（[Fpass?Fstop]/（Fs/2）?[1?0]?[Dpass?Dstop]）;
%?Calculate?the?coefficients?using?the?FIRPM?function.
bfir2??=?firpm（N?Fo?Ao?W?{dens}）;?%濾波器系數
FirCoeNum?=?length（bfir2）;????????????%濾波器長度

phase_Save?=?zeros（floor（num/Rate）1）;???%保存的角度
CodeS_Save?=?zeros（floor（num/Rate）1）;???%輸出碼元
Posion_Save?=?zeros（floor（num/Rate）1）;
Freq_Out???=?zeros（num1）;???????????????%載頻輸出
PhaseDert_Out?=?zeros（num1）;????????????%相位差輸出

Data_DoFreq?=?zeros（1num）;??????????????%下變頻后數據
Data_LoPass?=?zeros（1num）;??????????????%低通濾波后數據
????????
phase?=?0;?%相位
ss?=?0;????%自加項
dert_w?=?0;%頻差
dert_f?=?0;%相差

temp?=?0;
XX?=?0;
YY?=?0;

%%%考慮到濾波器因素跳過前面一

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----
?????文件????????5939??2018-03-29?14:24??Qpsk_Demod\QPSK_Demod.m
?????目錄???????????0??2018-03-29?20:58??Qpsk_Demod\