/*Adaptive filtering using the least mean square adaptation */
#include <math.h>
#include <dos.h>
#include <stdio.h>
#include <conio.h>
#include <graphics.h>
void initial_graphics (void);
float graph_outline (void);
int format ( double position);
void LJ_Graphic();
void draw_line (double D, double Y, long T, double D_1, double Y_1);
char key_status (void);
#define BACKGROUND BLACK
#define COLORTEXT LIGHTGRAY
#define TRACE1 RED
#define TRACE2 BLUE
#define N 30
#define NS 40
#define FS 8000
#define Pi 3.1415926
#define YSCALE 2
#define XSCALE NS/FS
#define DESIRED cos(2*Pi*T*1000/FS)
#define NOISE sin(2*Pi*T*1000/FS)
main()
{
char ch;
float beta;
long loop, I, T;
double D, Y, E, D_1, Y_1;
double W[N+1] = {0.0};
double X[N+1] = {0.0};
initial_graphics(); //initialize graphics
do //repeat graph for new beta value
{
beta = graph_outline(); //draw graph and read in value of beta
for (loop = 0; loop <= N+1; loop++) //initialize arrays to zero for new beta
{
W[loop] = 0.0; //coefficient array
X[loop] = 0.0; //array for noise samples
}
for (T = 0; T <= NS; T++) //start adaptive alogrithm
{
X[0] = NOISE; //new noise sample
D = DESIRED; //desired signal
Y = 0; //set output of filter to zero
for (I = 0; I <= N; I++)
Y = Y + (W[I] * X[I]); //calculate filter output
E = D - Y; //calculate error signal
for (I = N; I >= 0; I--)
{
W[I] = W[I] + (2*beta*E*X[I]); //update filter coefficients
if (I != 0)
X[I] = X[I-1]; //move data sample
}
draw_line (D,Y,T,D_1,Y_1); //plot output to display
D_1 = D; //D_1 is previous desired sample
Y_1 = Y; //Y_1 is previous output sample
}
ch = key_status(); //get instruction from user
setviewport (0,0,getmaxx(),getmaxy(),0);
clearviewport(); //clear screen for plot with new beta
}
while (ch == 0);
closegraph(); //return to text mode
return 0;
}
char key_status (void)
{
char ch;
while (!kbhit());
ch = getch();
if (ch == 0)
{
ch = getch();
if (ch == 59)
LJ_Graphic();
if (ch == 60)
return(0);
}
return(1);
}
void draw_line(double D, double Y, long T, double D_1, double Y_1)
{
if (T != 0)
{
setcolor(TRACE2);
setlinestyle(DASHED_LINE,1,1);
line((T-1)*(400/NS), (150 - (D_1 * 150/YSCALE)), (T * 400/NS),
(150 - (D * (150/YSCALE))));
setcolor(TRACE1);
setlinestyle(SOLID_LINE,1,1);
line((T-1)*(400/NS), (150 - (Y_1 * 150/YSCALE)), (T * 400/NS),
(150 - (Y * (150/YSCALE))));
setcolor(COLORTEXT);
}
}
void initial_graphics (void)
{
int gdriver = DETECT, gmode, errorcode; // request auto detection
initgraph(&gdriver, &gmode, ""); // initialize graphics mode
errorcode = graphresult(); // read result of initialization
if (errorcode != grOk) // an error occurred
{
printf("Graphics error: %s\n", grapherrormsg(errorcode));
printf("Press any key to halt:");
getch();
exit(1); // return with error code
}
}
float graph_outline (void)
{
int left, top, right, bottom, loop;
char str[25];
float beta;
printf ("Enter a real number for beta (Example 0.05). ");
scanf ("%f", &beta);
setbkcolor(BACKGROUND);
cleardevice();
setcolor(COLORTEXT);
left = getmaxx() / 2 - 200;
top = getmaxy() / 2 - 200;
right = getmaxx() / 2 + 200;
bottom = getmaxy() / 2 + 100;
settextjustify(CENTER_TEXT,CENTER_TEXT);
outtextxy (getmaxx()/2,top-20, "ADAPTIVE FILTER");
rectangle (left, top, right, bottom);
setviewport (left+1,top+1,right-1,bottom-1,1);
setlinestyle(DASHED_LINE, 1,1);
line(0,150,400,150);
setlinestyle(SOLID_LINE,1,1);
for (loop = 1; loop <= 7; loop++)
{
line(0,(loop*75)/2,5,(loop*75)/2); //draws horz hash marks
line(loop*80,300,loop*80,292); //draws vert hash marks
}
setviewport (left-50,top-10,right,bottom+10,1);
for (loop = 4; loop >= -4; loop--)
{
gcvt((-loop/(4.0)*YSCALE),2,str);
outtextxy(25,(loop*75)/2+160, str);
}
setviewport (left-20,top,right+50,bottom+140,0);
for (loop = 0; loop <= 5; loop++)
{
gcvt(loop/(5.0)*XSCALE, 10, str);
outtextxy((loop*80) + 20, 315, str);
}
outtextxy(220,340, "TIME");
settextstyle(DEFAULT_FONT, VERT_DIR, 1);
outtextxy (-50,150, "AMPLITUDE");
settextstyle(DEFAULT_FONT, HORIZ_DIR, 1);
settextjustify(LEFT_TEXT,CENTER_TEXT);
setcolor(TRACE1);
line(50,365,75,365);
setlinestyle(DASHED_LINE, 1,1);
setcolor(COLORTEXT);
outtextxy(80,365, "OUTPUT SIGNAL");
setcolor(TRACE2);
line(250,365,275,365);
setcolor(COLORTEXT);
outtextxy(280,365, "DESIRED SIGNAL");
settextjustify(RIGHT_TEXT,CENTER_TEXT);
outtextxy(150,385, "SAMPLING FREQ = ");
outtextxy(350,385, "SAMPLES = ");
outtextxy(150,400, "ORDER OF FILTER = ");
outtextxy(350,400, "BETA = ");
settextjustify(CENTER_TEXT,CENTER_TEXT);
outtextxy(75,425, "F1 for Printout");
outtextxy(225,425, "F2 for New BETA");
outtextxy(375,425, "ENTER to Quit");
settextjustify(LEFT_TEXT,CENTER_TEXT);
gcvt(FS*1.0, 10, str);
outtextxy (150, 385, str);
gcvt(NS*1.0, 10, str);
outtextxy (350, 385, str);
gcvt(N+1.0, 10, str);
outtextxy (150, 400, str);
gcvt(beta, 6, str);
outtextxy (350, 400, str);
settextjustify(CENTER_TEXT,CENTER_TEXT);
setviewport (left+1,top+1,right-1,bottom-1,1);
return(beta);
}
void LJ_Graphic()
{
int xaspect, yaspect, maxX, maxY, line, xword, pixel, xwidth, ywidth;
double xpos, ypos, prnstep, ratio;
char chr;
maxX = getmaxx(); //get number of horizontal pixel
maxY = getmaxy(); //get number of vertical pixel
getaspectratio(&xaspect, &yaspect); //get the screen aspect ratio
ratio = (double) xaspect/ (double) yaspect;
setviewport(0,0,maxX,maxY,0); //set viewport for full screen
xpos = 690; //initial position of prn cursor
ypos = 500; //initial position of prn cursor
prnstep = 7.2/ratio; //match printer aspr fo screen aspr
fprintf (stdprn, "\x1B&E\x1B&11H\x1B&1O\x1B*p0X\x1B*p0Y\x1B*t100R");
for (line = 0; line <= maxY; line++)
{
ywidth = 6;
if (ypos < 1000.0) ywidth--;
if (ypos < 100.0) ywidth--;
if (ypos < 10.0) ywidth--;
fprintf (stdprn, "\x1B&a%-*.1fh%-*.1fV", 5, xpos, ywidth, ypos);
ypos += prnstep;
fprintf (stdprn, "\x1B*r1A\x1B*b%dW", maxX/8);
for (xword = 0; xword < maxX/8; xword++)
{
chr = 0;
for (pixel = 0; pixel < 8; pixel++)
{ //reads series of 8 pixels to create graphics char
chr <<= 1;
if (getpixel (xword*8+pixel, line)) chr++;
}
fprintf (stdprn, "%c", chr); //sends graphic char to printer
}
fprintf (stdprn, "\x1B*rB"); //ends graphics line
}
fprintf (stdprn, "\x0C\x1B&10O\x1B&11H\x1B&E");
}