cellular-infrastructure
/
osmocom-analog
9
1
Fork 2
Code Issues 11 Pull Requests 2 Projects Releases Wiki Activity

SDR: Spectrum display will not scale FFT result 

Instead the greatest possible width that will fit into the window will
be used. This width is 2 to the power of N.
This commit is contained in:
Andreas Eversberg 2017-05-17 14:11:48 +02:00
parent ef7ff26793
commit 683078a7a0
2 changed files with 62 additions and 74 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/common/display.h
View File

@ -19,7 +19,7 @@ typedef struct display_iq {
float buffer[MAX_DISPLAY_IQ * 2];
} dispiq_t;
#define MAX_DISPLAY_SPECTRUM 256
#define MAX_DISPLAY_SPECTRUM 1024
typedef struct display_spectrum {
int interval_pos;

134
src/common/display_spectrum.c
View File

@ -94,19 +94,33 @@ void display_spectrum(float *samples, int length)
int pos, max;
double *buffer_I, *buffer_Q;
int color = 9; /* default color */
int i, j, k, count;
int m;
double I, Q, v, c;
int i, j, k, o;
double I, Q, v;
int s, e;
if (!spectrum_on)
return;
get_win_size(&width, &h);
if (width > MAX_DISPLAY_SPECTRUM)
width = MAX_DISPLAY_SPECTRUM;
if (width > MAX_DISPLAY_WIDTH)
width = MAX_DISPLAY_WIDTH;
int heigh[width], low[width];
/* calculate size of FFT */
int m, fft_size = 0, fft_taps = 0;
for (m = 0; m < 16; m++) {
if ((1 << m) > MAX_DISPLAY_SPECTRUM)
break;
if ((1 << m) <= width) {
fft_taps = m;
fft_size = 1 << m;
}
}
if (m == 16) {
fprintf(stderr, "Size of spectrum is not a power of 2, please fix!\n");
abort();
}
int heigh[fft_size], low[fft_size];
pos = disp.interval_pos;
max = disp.interval_max;
@ -114,7 +128,7 @@ void display_spectrum(float *samples, int length)
buffer_Q = disp.buffer_Q;
for (i = 0; i < length; i++) {
if (pos >= MAX_DISPLAY_SPECTRUM) {
if (pos >= fft_size) {
if (++pos == max)
pos = 0;
continue;
@ -122,106 +136,80 @@ void display_spectrum(float *samples, int length)
buffer_I[pos] = samples[i * 2];
buffer_Q[pos] = samples[i * 2 + 1];
pos++;
if (pos == MAX_DISPLAY_SPECTRUM) {
/* calculate number of taps */
for (m = 0; m < 16; m++) {
if ((1 << m) == MAX_DISPLAY_SPECTRUM)
break;
}
if (m == 16) {
fprintf(stderr, "Size of spectrum is not a power of 2, please fix!\n");
abort();
}
fft_process(1, m, buffer_I, buffer_Q);
count = 0;
c = 0.0;
if (pos == fft_size) {
fft_process(1, fft_taps, buffer_I, buffer_Q);
k = 0;
for (j = 0; j < MAX_DISPLAY_SPECTRUM; j++) {
for (j = 0; j < fft_size; j++) {
/* scale result vertically */
I = buffer_I[(j + MAX_DISPLAY_SPECTRUM / 2) % MAX_DISPLAY_SPECTRUM];
Q = buffer_Q[(j + MAX_DISPLAY_SPECTRUM / 2) % MAX_DISPLAY_SPECTRUM];
I = buffer_I[(j + fft_size / 2) % fft_size];
Q = buffer_Q[(j + fft_size / 2) % fft_size];
v = sqrt(I*I + Q*Q);
v = log10(v) * 20 + db;
if (v < 0)
v = 0;
v /= db;
/* scale down result horizontally by combining values */
if (v > c)
c = v;
buffer_max[j] -= DISPLAY_INTERVAL / 10.0;
if (c > buffer_max[j])
buffer_max[j] = c;
count += width;
while (count >= MAX_DISPLAY_SPECTRUM) {
if (k >= width) {
fprintf(stderr, "Too many output values, please fix!\n");
abort();
}
/* heigh is the maximum value */
heigh[k] = (double)(HEIGHT * 2 - 1) * (1.0 - buffer_max[j]);
if (heigh[k] < 0)
heigh[k] = 0;
if (heigh[k] >= (HEIGHT * 2))
heigh[k] = (HEIGHT * 2) - 1;
/* low is the current value */
low[k] = (double)(HEIGHT * 2 - 1) * (1.0 - c);
if (low[k] < 0)
low[k] = 0;
if (low[k] >= (HEIGHT * 2))
low[k] = (HEIGHT * 2) - 1;
k++;
c = 0.0;
count -= MAX_DISPLAY_SPECTRUM;
}
}
if (k != width) {
fprintf(stderr, "k must be %d but is %d, please fix!\n", width, k);
abort();
if (v > buffer_max[j])
buffer_max[j] = v;
/* heigh is the maximum value */
heigh[j] = (double)(HEIGHT * 2 - 1) * (1.0 - buffer_max[j]);
if (heigh[j] < 0)
heigh[j] = 0;
if (heigh[j] >= (HEIGHT * 2))
heigh[j] = (HEIGHT * 2) - 1;
/* low is the current value */
low[j] = (double)(HEIGHT * 2 - 1) * (1.0 - v);
if (low[j] < 0)
low[j] = 0;
if (low[j] >= (HEIGHT * 2))
low[j] = (HEIGHT * 2) - 1;
}
/* plot scaled buffer */
memset(&screen, ' ', sizeof(screen));
memset(&screen_color, 7, sizeof(screen_color)); /* all white */
sprintf(screen[0], "(spectrum log %.0f dB", db);
*strchr(screen[0], '\0') = ')';
for (j = 0; j < width; j++) {
o = (width - fft_size) / 2; /* offset from left border */
for (j = 0; j < fft_size; j++) {
s = e = low[j];
if (j > 0 && low[j - 1] > e)
e = low[j - 1] - 1;
if (j < width - 1 && low[j + 1] > e)
if (j < fft_size - 1 && low[j + 1] > e)
e = low[j + 1] - 1;
if (s == e) {
if ((s & 1) == 0)
screen[s >> 1][j] = '\'';
screen[s >> 1][j + o] = '\'';
else
screen[s >> 1][j] = '.';
screen_color[s >> 1][j] = 3;
screen[s >> 1][j + o] = '.';
screen_color[s >> 1][j + o] = 13;
} else {
if ((s & 1) == 0)
screen[s >> 1][j] = ':';
screen[s >> 1][j + o] = ':';
else
screen[s >> 1][j] = '.';
screen_color[s >> 1][j] = 3;
screen[s >> 1][j + o] = '.';
screen_color[s >> 1][j + o] = 13;
if ((e & 1) == 0)
screen[e >> 1][j] = '\'';
screen[e >> 1][j + o] = '\'';
else
screen[e >> 1][j] = ':';
screen_color[e >> 1][j] = 3;
screen[e >> 1][j + o] = ':';
screen_color[e >> 1][j + o] = 13;
for (k = (s >> 1) + 1; k < (e >> 1); k++) {
screen[k][j] = ':';
screen_color[k][j] = 3;
screen[k][j + o] = ':';
screen_color[k][j + o] = 13;
}
}
s = heigh[j];
e = low[j];
if ((s >> 1) < (e >> 1)) {
if ((s & 1) == 0)
screen[s >> 1][j] = ':';
screen[s >> 1][j + o] = ':';
else
screen[s >> 1][j] = '.';
screen_color[s >> 1][j] = 4;
screen[s >> 1][j + o] = '.';
screen_color[s >> 1][j + o] = 4;
for (k = (s >> 1) + 1; k < (e >> 1); k++) {
screen[k][j] = ':';
screen_color[k][j] = 4;
screen[k][j + o] = ':';
screen_color[k][j + o] = 4;
}
}
}
@ -230,7 +218,7 @@ void display_spectrum(float *samples, int length)
for (k = 0; k < width; k++) {
if (screen_color[j][k] != color) {
color = screen_color[j][k];
printf("\033[1;3%dm", color);
printf("\033[%d;3%dm", color / 10, color % 10);
}
putchar(screen[j][k]);
}