应用Matlab产生各种数字调制信号以及在AWGN下的传输结果

function [s,mod]=generate_mod_signal(type,total_time,fc,fs,symbol_rate) % total_time : length of signal in seconds % fc : carrier frequency % fs : samplling frequency % symbol_rate : symbol rate % type : modulation type if fs < 2*fc disp('error'); end alpha=0.5; ts=1/fs; T=1/symbol_rate; t=ts:ts:total_time; N=floor(total_time*fs); a=0.85; % modulation factor d=randn(1,N); [num,den]=butter(5,0.01); bs=filter(num,den,d); bs=bs/max(abs(bs)); t=ts:ts:total_time; te=-T+2*ts:2*ts:T; g_t=sinc(te/T).*cos(pi*alpha*te/T)./(1-(4*alpha*te/(2*T)).^2+eps); switch type case 1, % AM s=(1+a*bs).*cos(2*pi*fc*t); mod=1; case 2, % AM-DSB s=bs.*cos(2*pi*fc*t); mod=2; case 3, % AM-LSB s=bs.*cos(2*pi*fc*t)+imag(hilbert(bs)).*sin(2*pi*fc*t); mod=3; case 4, % AM-USB s=bs.*cos(2*pi*fc*t)-imag(hilbert(bs)).*sin(2*pi*fc*t); mod=4; case 5, % FM k=0.2*fc; int_bs(1)=0; for i=1:length(t)-1; int_bs(i+1)=int_bs(i)+bs(i)*ts; end s=cos(2*pi*fc*t+2*pi*k*int_bs); mod=5; case 6, % AM-FM-combined % k=0.02*fc; % int_bs(1)=0; % for i=1:length(t)-1; % int_bs(i+1)=int_bs(i)+bs(i)*ts; % end temps=amod(bs,fc,fs,'fm',0.2*fc); ms=hilbert(temps).*bs; s=real(ms); mod=6; case 7, % 2-ASK d=randint(1,floor(total_time*symbol_rate),2); dmap=modmap(d,symbol_rate,fs,'ask'); g_tr=repmat(g_t,1,length(d)); s=dmap.*g_tr.*cos(2*pi*fc*t); mod=7; case 8, % 4-ASK d=randint(1,floor(total_time*symbol_rate),4); dmap=modmap(d,symbol_rate,fs,'ask'); g_tr=repmat(g_t,1,length(d)); s=dmap.*g_tr.*cos(2*pi*fc*t); mod=8; case 9, % 16-QAM d=randint(1,floor(total_time*symbol_rate),16); s_r=dmod(d,fc,symbol_rate,fs,'qask'); g_tr=repmat(g_t,1,length(d)); s=g_tr.*s_r; mod=9; case 10, % 2-PSK d=randint(1,floor(total_time*symbol_rate),2); s_r=dmod(d,fc,symbol_rate,fs,'psk'); g_tr=repmat(g_t,1,length(d)); s=g_tr.*s_r; mod=10; case 11,% 4-PSK d=randint(1,floor(total_time*symbol_rate),4); s_r=dmod(d,fc,symbol_rate,fs,'psk'); g_tr=repmat(g_t,1,length(d)); s=g_tr.*s_r; mod=11; case 12, % 8-PSK d=randint(1,floor(total_time*symbol_rate),8); s_r=dmod(d,fc,symbol_rate,fs,'psk'); g_tr=repmat(g_t,1,length(d)); s=g_tr.*s_r; mod=12; case 13, % 2-FSK d=randint(1,floor(total_time*symbol_rate),2); s_r=dmod(d,fc,symbol_rate,fs,'fsk'); g_tr=repmat(g_t,1,length(d)); s=g_tr.*s_r; mod=13; case 14, % 4-FSK d=randint(1,floor(total_time*symbol_rate),4); s_r=dmod(d,fc,symbol_rate,fs,'fsk'); g_tr=repmat(g_t,1,length(d)); s=g_tr.*s_r; mod=14; case 15, % MFSK d=randint(1,floor(total_time*symbol_rate),2); s_r=dmod(d,fc,symbol_rate,fs,'msk'); g_tr=repmat(g_t,1,length(d)); s=g_tr.*s_r; mod=15; end