MUHAMMAD AL-XORAZMIY
NOMIDAGI TOSHKENT AXBOROT
TEXNOLOGIYALARI UNIVERSITETI
811-20 guruh talabasi Abdisalomov
Avazbekning raqamli aloqa fanidan
8-9-amaliy ishi
Tekshirdi: Tashmetov Shaxzod
Raqamli aloqa faza siljishini boshqarish. Kvadratik faza siljishi
manipulyatsiyasi
Kvadratik
faza
siljishi
manipulyatsiyasi
(QPSK)
fazani
almashtirishning bir shakli bo'lib, unda ikkita bit bir vaqtning o'zida
modulyatsiya qilinadi va to'rtta mumkin bo'lgan tashuvchining fazali
siljishidan (0, 90, 180 yoki 270 daraja) birini tanlaydi. QPSK signalni bir
xil tarmoqli kengligidan foydalangan holda oddiy PSKga qaraganda ikki
baravar ko'p ma'lumot uzatish imkonini beradi.
1-rasm. QPSK modulatori
Modulyatorning kirishida xabar signalining juft bitlari (ya'ni, 2-bit,
4-bit, 6-bit va boshqalar) va toq bitlar (ya'ni, 1-bit, 3-bit, 5-bit va
boshqalar) bitlarni ajratuvchi va toq BPSK (PSKI deb ataladi) va hatto
BPSK (PSKQ deb ataladi) hosil qilish uchun bir xil tashuvchi bilan
ko'paytiriladi. PSKQ signali modulyatsiyadan oldin faza 90 ° ga siljiydi.
Ikki bitli kirish uchun QPSK to'lqin shakli quyidagicha bo'lib, u ikkilik
kirishlarning turli misollari uchun modulyatsiyalangan natijani ko'rsatadi.
QPSK demodulyatori
QPSK Demodulyatori mahalliy osilator, ikkita tarmoqli o'tish filtri,
ikkita integrator sxemasi va ketma-ket konvertorga parallel ravishda 2
bitli ikkita mahsulot demodulyatori sxemasidan foydalanadi. Quyida
xuddi shunday diagramma keltirilgan.
Demodulyatorning kirish qismidagi ikkita mahsulot detektori bir vaqtning
o'zida ikkita BPSK signalini demodulyatsiya qiladi. Bitlar juftligi bu erda
asl ma'lumotlardan tiklanadi. Ushbu signallar qayta ishlangandan so'ng,
parallel ravishda ketma-ket konvertorga uzatiladi.
Task (1-variant)
Matlab kodi (8-ish):
clear all
clf
char=double ('PENCIL')
Ac=1;
As=Ac
fc=1.5;
first_data=0
a (1:2)=first_data;
t1(1:2)=[0,1];
i=3;
for cc=1:length(char)
for n=0:2:7
bit_n=bitshift(char(cc),-n);
a(i:i+1) = bitand(bit_n,3);
t1(i) = (i-1)/2;
t1(i+1) = t1(i)+1;i=i+2;
end; end
for j=1:length(char)*20000+4999
t2(j)=j/5000;
i=floor(t2(j)*2+1);
c(j)=Ac*sin(2*pi*fc*t2(j));
s(j)=Ac*sin(2*pi*fc*t2(j)+a(i)*pi/2+pi/4);
end
subplot(4,1,1);
plot(t1,a);
subplot(4,1,2);
plot (t2,c);
subplot (4,1,3);
plot (t2,s,'.');
last_data=first_data;
buff_data=first_data
time_c=1;
rec_data(1:2)=first_data;
rec_time (1:2)=[first_data,1];
rec_c=3;
for j=4:length(s)
if t2(j)>time_c-0.2
if abs (s(j-1)-s(j-2))>Ac*0.1
change_point=t2(j-1)
buff_data=get_data(s(j-3:j),last_data);
else
if abs (s(j-2))<Ac*0.95&&(s(j-3)<s(j-2)&&s(j-1)>s(j)||s(j3)>s(j-2)&&s(j-1)<s(j))
change_point=t2(j)
buff_data=get_data(s(j-3:j),last_data);
end; end; end
if t2(j)>time_c
last_data=buff_data
rec_data(rec_c:rec_c+1)=last_data;
rec_time(rec_c:rec_c+1)=[time_c, time_c+1];
time_c=time_c+1;
rec_c=rec_c+2;
end
end
subplot(4,1,4);
plot(rec_time,rec_data)
function res=get_data (s,last_data)
degree2=asin(double(s(2)))/pi*180;
degree3=asin(double(s(3)))/pi*180;
if s(2)>s(1)
if degree2<0 degree2=360+degree2; end
else
if degree2>0 degree2=180-degree2;
else degree2=abs (180-degree2); end
end
if s(4)>s(3)
if degree3<0 degree3=360+degree3;end
else
if degree3>0 degree3=180-degree3;
else degree3=abs (180-degree3); end
end
degree2=degree2-last_data*90;
degree3=mod(degree3-degree2,360);
res=round (degree3/90); end
Matlab kodi (9-ish):
clear all
char=double(input('Binary letter codes for the first letter of your
name : '));
Ac=1;
As=Ac
fc=1.5;
first_data=0
a (1:2)=first_data;
t1(1:2)=[0,1];
i=3;
for cc=1:length(char)
for n=0:2:7
bit_n=bitshift(char(cc),-n);
a(i:i+1) = bitand(bit_n,3);
t1(i) = (i-1)/2;
t1(i+1) = t1(i)+1;i=i+2;
end; end
for j=1:length(char)*20000+4999
t2(j)=j/5000;
i=floor(t2(j)*2+1);
c(j)=Ac*sin(2*pi*fc*t2(j));
s(j)=Ac*sin(2*pi*fc*t2(j)+a(i)*pi/2+pi/4);
end
subplot(4,1,1);
plot(t1,a);
subplot(4,1,2);
plot (t2,c);
subplot (4,1,3);
plot(t2,s,'.');
last_data=first_data;
buff_data=first_data;
time_c=1;
rec_data(1:2)=first_data;
rec_time (1:2)=[first_data,1];
rec_c=3;
for j=4:length(s)
if t2(j)>time_c-0.2
if abs (s(j-1)-s(j-2))>Ac*0.1
change_point=t2(j-1);
buff_data=get_data(s(j-3:j),last_data);
else
if abs (s(j-2))<Ac*0.95 && (s(j-3)<s(j-2) && s(j-1)>s(j) || s(j3)>s(j-2) && s(j-1)<s(j))
change_point=t2(j);
buff_data=get_data(s(j-3:j),last_data);
end; end; end
if t2(j)>time_c
last_data=buff_data;
rec_data(rec_c:rec_c+1)=last_data;
rec_time(rec_c:rec_c+1)=[time_c, time_c+1];
time_c=time_c+1;
rec_c=rec_c+2;
end
end
subplot(4,1,4);
plot(rec_time,rec_data)
function res=get_data (s,last_data)
degree2=asin(double(s(2)))/pi*180;
degree3=asin(double(s(3)))/pi*180;
if s(2)>s(1)
if degree2<0 degree2=360+degree2; end
else
if degree2>0 degree2=180-degree2;
else degree2=abs (180-degree2); end
end
if s(4)>s(3)
if degree3<0 degree3=360+degree3;end
else
if degree3>0 degree3=180-degree3;
else degree3=abs(180-degree3); end
end
degree2=degree2-last_data*90;
degree3=mod(degree3-degree2,360);
res=round (degree3/90); end
Binary letter codes
A: 01000001.
Binary letter codes
A: 01000001.