H tn Nguyn c Mnh

H tn Nguyn c Mnh

MSSV 20122055

Lp TTT 08 K57

GVHD: C Nguyn Thu Nga

Project I : iu ch QPSK trn KIT C6416

Bo co tun 8: Code khi gii iu ch

I. Yu cu tin -Tm hiu v s khi khi gii iu ch QPSK trn KIT TMS320C6416

-Phn chia tm hiu code tng khi.

II. Ni dung

1. S khi khi gii iu ch 4-PSK:

Gii thch cc khi: + T tn hiu vo ca sng QPSK: c th l dng hnh + Khi Carrier recovery : Phc hi sng mang cho li sng mang t tn hiu nhn c

+ Sau khi thu c sng sin t khi phc hi sng mang. Tn hiu c a vo mch nhn ng (Bal mod) I v lm lch pha 90 trc khi cho vo mch nhn ng Q. T cc u ra ca mch nhn ng tn hiu a vo khi m tn loi b thnh phn tn s cao gip cho tn hiu c mn hn v trnh nhng xung tn hiu ngn thu tn hiu di hn. Cn cc gi tr DC c gi li tng hp mch tng bit combiner.

V d :

Gi s tn hiu vo l tn hiu nhn c trong th d trn: cosct - sinct

Tn hiu ra mch nhn ng I l:

sinct ( cosct - sinct) = 1/2sin2ct - 1/2(1-cos2ct)

Tn hiu ra sau mch lc l in th dc -, tng ng bit 0

Tn hiu ra mch nhn ng Q l:

cosct ( cosct - sinct) = -1/2sin2ct + 1/2(1+cos2ct)

Tn hiu ra sau mch lc l in th dc+, tng ng bit 1,

Mch t hp bit s cho li d liu nh pht : 01

Tin hnh code cc khi

2.1 Bt u vi chng trnh CCS (Code Compose Studio)

-Thc hin code project trn CCS 3.1 vi h iu hnh win XP

2.1.1 Tin hnh ci t cu hnh s dng cc file h thng:

2.1.2 Khi to project mi

Bm Finish

Thm file vo chng trnh thc hin code:

t tn main.c

Add cc file th vin vo chng trnh. y chng

ta lm vic vi chip C6416 nn chng ta s Add file rts6400.lib

trong th mc C:\Program

Files\CCStudio_v3.1\C6000\cgtools\lib vo chng trnh nh

Add file ngun bc 3.

-Click Scan All File Dependencies tham chiu cc

file.h vo chng trnh. Cc file.h ny s t ng c to ra.

2.1.3 Tip tc chn thay i tn s cho DSK

Vy l chng ta hon thnh vic cu hnh v lm quen vi CCS trong vic lp trnh code

Code tng khi

-Thut ton v hng gii quyt:

3.1 Khi u vo Bi ton gii m QPSK t u vo l sng QPSK. V vy ta xt u vo l chui sng QPSK c chia tng on vi di l chu k ca sng mang. T , xc nh tng s on sng a vo cc khi gii m bit. V d: Sng vo c dng

Xc nh tn s ca sng mang t ct sng thnh cc khong chu k

Cc khong chu k ny s c a vo hm xc nh sng sin hay cos hay l tng ca 2 sng

Cc hm s c xy dng sau:

double determine_wave(double *tanso)

{

//code here

return 1; //neu la song sin -cos

return 2;// song sin +cos

return 1;//song -sin + cos

return 1;//song -sin - cos

...

};

3.2 Khi qua mch nhn ng

T khi nhn c tn hiu vo s i qua b phc hi sng mang sang dng sin(wt). c nhn li vi sng vo to thnh t hp trc khi qua b lc m tn

#include "dsk6416_aic23.h" //codec-DSK support file

#include dsk6416.h

#include

#include

Uint32 fs=DSK416_AIC23_FREQ_16KHZ; //set sampling rate

#define PI 3.1415926

#define N 16 //# samples per symbol

#define MAX_DATA_LENGTH 10 //size of mod/demod vector

double DeMOD_QPSK(complex reciv_sig_equal) //recv_sig with noise

{

double d[4];

double small;

int dec_bit, loc = 0;

double x2, y2;

x2 = real(reciv_sig_equal);

y2 = imag(reciv_sig_equal);

d[0] = sqrt(pow(x2 - (-sqrt(2) / 2), 2) + pow(y2 - (-sqrt(2) / 2), 2));

d[1] = sqrt(pow(x2 - (-sqrt(2) / 2), 2) + pow(y2 - sqrt(2) / 2, 2));

d[2] = sqrt(pow(x2 - ( sqrt(2) / 2), 2) + pow(y2 - ( sqrt(2) / 2), 2));

d[3] = sqrt(pow(x2 - sqrt(2) / 2 , 2) + pow(y2 - (-sqrt(2) / 2), 2));

small = d[0];

for (int j = 1; j