sync.c

详细的OFDM设计过程

#include <stdio.h>
#include <math.h>


int sync(float *in , const float *training_seq) {
	
	int i;
	int k;
	float corr[2*PADDING];
	float temp[TRAININGSIZE];
	float sum;
	int index;
	float max = 0;


	for (i=0;i<(2*PADDING);i++) {   // we assume the delay is not larger than twice the padding

	sum=0;	

		for(k=0;k<TRAININGSIZE;k++) {

			temp[k] = in[k+i];
			temp[k] = temp[k]*training_seq[k];
			sum=sum+temp[k];

		}
		corr[i]=sum;
	}

	i=0;
	
	for (i;i<(2*PADDING);i++) {

		if (corr[i] > max) {

			max = corr[i];
			index = i;
		}
	}
return index;
}

int approxnext(int ind) {

	return ind + GUARD + UPFRAME_SIZE;
}



void extracting (float *in, float *out, int index ) {   //extract , downsample and store the frame in a buffer

	int m;
	for (m=0;m<FRAME_SIZE;m++){

		out[m]=in[index+m*UPFACTOR];
	}
}



	void main() {
	int i;
	int k;
	int index;
	float in[BUFFSIZE];
	float out[FRAME_SIZE];
	float training[42];
	for(i=0;i<20;i++)  in[i]=0;
	for(i=20;i<62;i++) in[i]=i;
	for(i=62;i<828;i++) in[i]=-i;
	for(i=828;i<840;i++) in[i]=0;
	for(k=0;k<42;k++) training[k]=k+20;
	index=sync(in,training);
	printf("first sample of the frame is %d \n",index); 
	extracting(in, out, index);
	printf("the first elements of the frame are %f  %f  %f \n",out[0],out[1],out[2]); 
}