Mã nguồn chương trình Matlab: 1.Mã NRZ: file nrz_l.m function y=nrz_l(x) for i=1:length(x) if x(i)==0 temp(i) = -1; else temp(i) = +1; end; end y=temp; 2.Mã CMI: file cmi_1.m function y = cmi(x); polar = +1; %chon cuc tinh cua bit 1 dau tien la duong for i=1:length(x) if x(i)==1 temp(2*i-1) = polar; temp(2*i) = polar; polar = -polar; %xac dinh cuc tinh cho bit 1 tiep theo else temp(2*i-1) = -1; temp(2*i) = +1; end end y = temp; 3.Mã HDB3: File hdb3.m function y = hdb3(x) next_polar = +1; b=0; %so bit B giua 2 bit V i=1; while i<= length(x) if x(i)==1 temp(i)=next_polar; next_polar = -next_polar; b=b+1; i=i+1; else if (i<=length(x)-3)&(x(i+1)==0) & (x(i+2)==0) & (x(i+3)==0) %truong hop 4 bit 0 lien tiep if mod(b,2)==1 temp(i) = 0; %bit 0 temp(i+1) = 0; %bit 0 temp(i+2) = 0; %bit 0 temp(i+3) = -next_polar;%bit V next_polar = -next_polar; b=0; i=i+4; else temp(i) = next_polar; %bit B temp(i+1) = 0; %bit 0 temp(i+2) = 0; %bit 0 temp(i+3) = next_polar; %bit V next_polar = -next_polar; b=0; i=i+4; end else temp(i)=0; %truong hop 3 bit ke tiep khac 000 i=i+1; end end