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authorAndreas Eversberg <jolly@eversberg.eu>2017-05-17 14:11:48 +0200
committerAndreas Eversberg <jolly@eversberg.eu>2017-05-17 20:06:46 +0200
commit683078a7a01903c9bcbac196148f132fc00be6ad (patch)
tree6b7ed30577a3984fe68953014e755cf7641a8b3a /src/common
parentef7ff26793b290d5ee3725a5490f6e5bfeb7b5da (diff)
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.
Diffstat (limited to 'src/common')
-rw-r--r--src/common/display.h2
-rw-r--r--src/common/display_spectrum.c134
2 files changed, 62 insertions, 74 deletions
diff --git a/src/common/display.h b/src/common/display.h
index 59b1b4c..9f476de 100644
--- a/src/common/display.h
+++ b/src/common/display.h
@@ -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;
diff --git a/src/common/display_spectrum.c b/src/common/display_spectrum.c
index fcdd706..ef5e577 100644
--- a/src/common/display_spectrum.c
+++ b/src/common/display_spectrum.c
@@ -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;
+
+ /* 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[width], low[width];
+ 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]);
}