Eugene
Guest
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 Posted:
Mon Dec 20, 2004 1:15 pm Post subject:
FFT build with DSP |
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Hi,
hier is my quelltext,
Can anybody say me, what is in my program false.
I want to produce a sine or rectangle inputsignal, and build fft
spectrum from it.
then I take a absolut value from the result and display it in ccs
"single-time"
if the input is sine then I haven't only one peak (or two, if it's
symmetrical) and if I have rectangle input, then I haven't a harmonic
waves in my spectrum.
I thank you in advance
///////////////////////////////////
#include <math.h>
#include <tms320.h>
#include <dsplib.h>
#include <stdio.h>
#define NX 128
#define SINE_MAX 0x7FFE
#define SINE_TABLE_SIZE 256
#define PI ((double)3.1415927)
short scale = 1;
short x1[2*NX];
int sinetable[SINE_TABLE_SIZE];
DATA prueftest[SINE_TABLE_SIZE];
DATA prueftest1[SINE_TABLE_SIZE];
DATA prueftest2[SINE_TABLE_SIZE];
DATA prueftest3[SINE_TABLE_SIZE];
void InitSineTable(void)
{
int counter1=0;
int signal_Wert=1;
int i=30;
double increment= 0;
double radian = 0;
/*Hier will produce a rectangle input*/
while(i||counter1!=255)
{
i--;
if(i==0)
{
i=30;
if(signal_Wert)
signal_Wert=0;
else
signal_Wert=1;
}
sinetable[counter1]=signal_Wert;
counter1++;
if(counter1==256)
break;
}
/*Hier WILL BE PRODUCE a sine input
increment = (PI * 2) / SINE_TABLE_SIZE;
for (i = 0; i < SINE_TABLE_SIZE; i++)
{
sinetable[i] = (int)(sin(radian) * SINE_MAX);
radian += increment;
}*/
for (i=0;i<SINE_TABLE_SIZE;i++)
prueftest[i]=sinetable[i];
}void main()
{int NumUniquePts=0;
int i=0,j=0;
int counter1=0;
float temp1=0.0;
float temp2=0.0;
float temp3=0.0;
float temp4=0.0;
for(i=0;i<SINE_TABLE_SIZE;i++)
{
sinetable[i]=0;
prueftest[i]=0;
prueftest1[i]=0;
prueftest2[i]=0;
prueftest3[i]=0.0;
}
// Initialize the Inputsignal
InitSineTable();
NumUniquePts=(int)((NX+1)/2);
for(i=0;i<SINE_TABLE_SIZE;i++)
prueftest3[i]=0.0;
// compute the real fft
cbrev(prueftest,prueftest2,NX);
rfft(prueftest2,SINE_TABLE_SIZE,scale);
//Calculate the numberof unique points
j=sizeof(prueftest);
i=0;
counter1=0;
/*
Hier will be shown two variation. I I'm not sure, that one of this is
correct
you should remove the commentary
*/
// Take the magnitude of fft of x Hier will calculate the abs(input)
for(i=0;i<(SINE_TABLE_SIZE-1);i+=2)
{
temp1=(float)((float)prueftest2[i]*(float)prueftest2[i]);
temp2=(float)((float)prueftest2[i+1]*(float)prueftest2[i+1]);
temp3=temp2+temp1;
temp4=(float)sqrt((double)temp3);
prueftest3[counter1]=(DATA)temp4;
counter1++;
}
// then the value of prueftest3 will be display in time/frequenz-
single Time
printf("Hallo Leute");
}
////////////////////////// |
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Shawn Steenhagen
Guest
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| Posted:
Tue Dec 21, 2004 1:02 am Post subject:
Re: FFT build with DSP |
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"Eugene" <johnbesel@web.de> wrote in message
news:6484110f.0412200015.4fd13c7b@posting.google.com...
| Quote: |
///////////////////////////////////
#include <math.h
#include <tms320.h
#include <dsplib.h
#include <stdio.h
#define NX 128
#define SINE_MAX 0x7FFE
#define SINE_TABLE_SIZE 256
#define PI ((double)3.1415927)
short scale = 1;
short x1[2*NX];
int sinetable[SINE_TABLE_SIZE];
DATA prueftest[SINE_TABLE_SIZE];
DATA prueftest1[SINE_TABLE_SIZE];
DATA prueftest2[SINE_TABLE_SIZE];
DATA prueftest3[SINE_TABLE_SIZE];
{Snip}
// compute the real fft
cbrev(prueftest,prueftest2,NX);
rfft(prueftest2,SINE_TABLE_SIZE,scale);
{Snip..}
// Take the magnitude of fft of x Hier will calculate the abs(input)
for(i=0;i<(SINE_TABLE_SIZE-1);i+=2)
{
temp1=(float)((float)prueftest2[i]*(float)prueftest2[i]);
temp2=(float)((float)prueftest2[i+1]*(float)prueftest2[i+1]);
temp3=temp2+temp1;
temp4=(float)sqrt((double)temp3);
prueftest3[counter1]=(DATA)temp4;
counter1++;
}
// then the value of prueftest3 will be display in time/frequenz-
single Time
printf("Hallo Leute");
}
//////////////////////////
|
At first glance I would make sure that the variables prueftest[],
prueftest2[ ] are aligned on 2*nx = 2*256 = 512 word boundaries by using the
..align directive in your linker command file. Since I don't see the use of
the #pragma DATA_SECTION directive, I'll bet you aren't putting these
variables in a special section so that you can tell the linker command file
to align variables in this section on the proper boundary.
Look at the example in C:\ti\c5400\dsplib\examples\rfft.
Look at test.h and the linker command file for that example..
-Shawn |
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