int snr = 0; // TODO: compute SNR

[F4HTB]

Hello dear!

Thanks for your application.
I try to use it for specific beacon.
I just whant to ask you if it's possible to complet the snr for each num_candidates?

Thanks ;)

[F4HTB]

Hello,

I have maybe a solution.
I add this in decode.c:

void swap(int* xp, int* yp)
{
	int temp = *xp;
	*xp = *yp;
	*yp = temp;
}
 
// Function to perform Selection Sort
void selectionSort(int arr[], int n)
{
	int i, j, min_idx;
  
	// One by one move boundary of unsorted subarray
	for (i = 0; i < n-1; i++)
	{
		// Find the minimum element in unsorted array
		min_idx = i;
		for (j = i+1; j < n; j++)
		  if (arr[j] < arr[min_idx])
			min_idx = j;
  
		// Swap the found minimum element with the first element
		swap(&arr[min_idx], &arr[i]);
	}
}

int get_snr(const waterfall_t* wf, candidate_t candidate)
{
	
	//array with wf.num_blocks (row of watterfall) x 8*wf.freq_osr (signals witdh)
	//Get this watterfall zoom on the candidate symbols
	//Sort max to min and calculate max/min = ft8snr and return with substract of -26db for get snr on 2500hz
	
	float freq_hz = (candidate.freq_offset + (float)candidate.freq_sub / 2) / 0.160f;
	
	float minC = 0, maxC = 0;
	
	int i = 0;
	while(i<wf->num_blocks){
		
		int candidate_zoom[8*wf->freq_osr*wf->time_osr];
		
		for(int j = 0; j< 8; j++){
			
			for(int k = 0; k<wf->freq_osr*wf->time_osr; k++){
			
			candidate_zoom[(j*wf->freq_osr*wf->time_osr)+k] = wf->mag[( (i * wf->block_stride) + candidate.freq_offset + candidate.freq_sub + (j*wf->freq_osr*wf->time_osr) + k )];
			}

		}

		
		selectionSort(candidate_zoom,8*wf->freq_osr*wf->time_osr);
		
		for(int j = 0; j< wf->freq_osr*wf->time_osr*2; j++){
			minC += candidate_zoom[j+(2*wf->freq_osr*wf->time_osr)];
			
		}
		
		for(int j = 1; j<= wf->freq_osr*wf->time_osr; j++){
			maxC += candidate_zoom[(8*wf->freq_osr*wf->time_osr)-j];
			
		}
		
		i++;
	
	}

	minC = minC / (wf->num_blocks*wf->freq_osr*wf->time_osr*2);
	maxC = maxC / (wf->num_blocks*wf->freq_osr*wf->time_osr);
	
	int min = (int)(minC/2 - 240);
	int max = (int)(maxC/2 - 240);
	int snr= max - min - 26;
	
	return snr;
	
}

in ft8_find_sync i add:

...
	for(int i = 0; i<heap_size; i++){
		heap[i].snr = get_snr(wf,heap[i]);
	}

	return heap_size;
}

In decode.h

typedef struct
{
    int16_t score;       ///< Candidate score (non-negative number; higher score means higher likelihood)
    int16_t time_offset; ///< Index of the time block
    int16_t freq_offset; ///< Index of the frequency bin
    uint8_t time_sub;    ///< Index of the time subdivision used
    uint8_t freq_sub;    ///< Index of the frequency subdivision used
int16_t snr;         ///< SNR
} candidate_t;

[kholia]

@F4HTB Check out the https://github.com/kgoba/ft8_lib/tree/update_to_0_2 branch. It is able to generate SNR values similar to WSJT-X now.