function?[Y]=DSSS（X?mode）
%?完成DSSS調制解調功能
%?mode=[12].??1進行調制，2進行解調，未指定時自動完成調制和解調兩個功能。
switch?nargin
????case?0
????????X=‘This?is?a?test.‘;
????????Y=DSSS（X）;
????????return
????case?1
????????Y1=DSSS（X?1）;?
????????Y2=DSSS（Y1?2）;
????????Y=Y2;
????????return;
????case?2
????????if?mode==1%調制
????????????D=ones（17）;
????????????m_sequence=Msequence（D）;
????????????X_length=length（X）;
????????????ascii_value=abs（X）;
????????????ascii_binary=zeros（X_length7）;
????????????%將數據轉換為ASCII二進制碼
????????????for?ii=1:X_length
????????????????ascii_binary（ii:）=Binary（ascii_value（ii））;
????????????end
????????????subplot（231）;plot（reshape（ascii_binary1X_length*7））;title（‘A:輸入數據‘）;
????????????%擴頻
????????????Sp_expand=zeros（X_length127*7）;
????????????for?ii=1:X_length
????????????????for?jj=1:7
????????????????????Sp_expand（ii127*jj-126:127*jj）=xor（m_sequenceascii_binary（iijj））;
????????????????end
????????????end
????????????subplot（232）;plot（reshape（Sp_expand1X_length*127*7））;title（‘B:數據擴展‘）;
????????????%將擴頻碼轉換為BPSK（1-1）序列
????????????for?ii=1:X_length
????????????????for?jj=1:127*7
????????????????????if~（Sp_expand（iijj））
????????????????????????Sp_expand（iijj）=-1;
????????????????????end
????????????????end
????????????end
????????????Sp_expand_bpsk=reshape（Sp_expand1X_length*127*7）;
????????????subplot（233）;plot（Sp_expand_bpsk）;title（‘C:BPSK調制‘）
????????????Y=Sp_expand_bpsk;
????????elseif?mode==2%解調
????????????D=ones（17）;
????????????m_sequence=Msequence（D）;
????????????%將BPSK雙極性轉換為單極性
????????????l=length（X）/（127*7）;
????????????X_length=length（X）;
????????????for?ii=1:X_length
????????????????if?X（ii）==-1
????????????????????X（ii）=0;
????????????????end
????????????end
????????????Sp_expand=reshape（Xl127*7）;
????????????subplot（234）;plot（X）;title（‘D:數據傳輸‘）;
????????????ascii_binary=zeros（l7）;
????????????Demodulate_binary=zeros（l127*7）;
????????????%接收處解調
????????????for?ii=1:l
????????????????for?jj=1:7
????????????????????Demodulate（ii127*jj-126:127*jj）=xor（m_sequence?Sp_expand（ii127*jj-126:127*jj））;
????????????????end
????????????end
????????????for?ii=1:l
????????????????for?jj=1:7
????????????????????ascii_binary（iijj）=Demodulate（ii127*jj-126）;
????????????????end
????????????end
????????????subplot（236）;plot（reshape（ascii_binary1l*7））;title（‘E:數據輸出‘）;
????????????%將ASCII二進制轉換為輸出數據
????????????A=zeros（1l）;
????????????for?ii=1:l
????????????????A（ii）=Ascii（ascii_binary（ii:））;
????????????end
????????????Y=char（A）;
????????else
????????????mode=1;
????????end
????????return
end
%代碼主體，執行中畫出各點波形。
%ASCII數值二進制比特轉換
function?[YY]=Binary（Z1）
z=zeros（17）;
z（1）=mod（Z12）;
a=floor（Z1/2）;
for?ll=1:6
????z（ll+1）=mod（a2）;
????a=floor（a/2）;
????if?a==0
????????break;
????end
end
YY=z;
%二進制比特轉換為ASCII數值
function?[ZZ]=Ascii（Z2）
l=length（Z2）;
A=0;
for?ii=1:l
????A=Z2（ii）*2^（ii-1）+A;
end
ZZ=A;
%生成m序列
function?[Y]=

?屬性????????????大小?????日期????時間???名稱
-----------?---------??----------?-----??----

?????文件???????3743??2010-04-13?16:35??DSSS.m

-----------?---------??----------?-----??----

?????????????????3743????????????????????1