dpsk调制以及相干解调系统matlab代码：可直接运行

clc
clear all
close all
% DPSK system
% assuming to have ideal channel H（z）=1
% AWGN
% initiate variances

symbol_num0=14;
symbol_num=symbol_num0+1;
b_d=zeros（1symbol_num0）; % relative code
Rs=1200;                  % symbol rate
T=10;   % oversampling 7 points per symbol
s_t=zeros（1symbol_num*T）;
f_C=1800; % the carrier frequence is 1800 Hz
fs=Rs*T;
ts=1/fs;
Eb=1;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Tx  %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% carrier generate 
t=0:1/fs:（symbol_num*T-1）/fs;
carrier_sig= sin（2*pi*f_C*t）;

% code exchanger （absolute to differential）
b_org=unifrnd（-111symbol_num0）>0; % the absolute sequence b_n
%b_org=[1 0 0 1 0 0 1 1];
b_d（1）=1;                           % initiate the d_（n-1）‘s d（1）=1
for i=2:1:symbol_num                % get the d_（n-1）
    b_d（i）=xor（b_org（i-1）b_d（i-1））;
end

% generate the square series with message
for n=1:symbol_num*T
    n_temp=ceil（n/T）;
    s_t（n）=b_d（n_temp）;
end

% another way to generate the dpsk 
s1=s_t.*carrier_sig;
s2=（ones（1symbol_num*T）-s_t）.*（-carrier_sig）;
%（-carrier means phase shift in pi）
s_t=s1+s2; % transmition signal is s_t



EbN0=20;
%%%%%%%%%%%%%%%%%%% creating the AWGN %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
mu=0;
N0=Eb/（10^（EbN0/10））;
sigma=sqrt（N0*2）;
gs_noise=normrnd（musigma[1 symbol_num*T]）;
%another way: awgn（xsnr）
%gs_noise=zeros（1symbol_num*T）;
%gs_noise=awgn（gs_noiseEbN0）;
s_t1=s_t+gs_noise;
%s_t1=awgn（s_tEbN0‘measured‘）;


%%%%%%%%%%%%%%%%%%%% Rx DPSK demodulation %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% pass a bandpass filter to get R_temp
lowpassband=f_C-Rs;
highpassband=f_C+Rs;
order=40;         % expecially the time of T
wn=[lowpassband highpassband]/（fs/2）;
Filter_coefficient=fir1（orderwn）;
R_temp=filter（Filter_coeffi