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Do tuner gain setting properly.

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(cherry picked from commit c06a537c8143af8e363fde677043053cefff1612)
This commit is contained in:
Oliver Jowett 2015-01-10 23:52:37 +00:00
parent e54b290601
commit e701f883b3
1 changed files with 48 additions and 10 deletions
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58
dump1090.c
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@ -235,17 +235,55 @@ int modesInitRTLSDR(void) {
rtlsdr_set_tuner_gain_mode(Modes.dev,
(Modes.gain == MODES_AUTO_GAIN) ? 0 : 1);
if (Modes.gain != MODES_AUTO_GAIN) {
if (Modes.gain == MODES_MAX_GAIN) {
// Find the maximum gain available
int numgains;
int gains[100];
int *gains;
int numgains;
numgains = rtlsdr_get_tuner_gains(Modes.dev, gains);
Modes.gain = gains[numgains-1];
fprintf(stderr, "Max available gain is: %.2f\n", Modes.gain/10.0);
numgains = rtlsdr_get_tuner_gains(Modes.dev, NULL);
if (numgains <= 0) {
fprintf(stderr, "Error getting tuner gains\n");
return -1;
}
gains = malloc(numgains * sizeof(int));
if (rtlsdr_get_tuner_gains(Modes.dev, gains) != numgains) {
fprintf(stderr, "Error getting tuner gains\n");
free(gains);
return -1;
}
if (Modes.gain == MODES_MAX_GAIN) {
int highest = -1;
int i;
for (i = 0; i < numgains; ++i) {
if (gains[i] > highest)
highest = gains[i];
}
Modes.gain = highest;
fprintf(stderr, "Max available gain is: %.2f dB\n", Modes.gain/10.0);
} else {
int closest = -1;
int i;
for (i = 0; i < numgains; ++i) {
if (closest == -1 || abs(gains[i] - Modes.gain) < abs(closest - Modes.gain))
closest = gains[i];
}
if (closest != Modes.gain) {
Modes.gain = closest;
fprintf(stderr, "Closest available gain: %.2f dB\n", Modes.gain/10.0);
}
}
free(gains);
fprintf(stderr, "Setting gain to: %.2f dB\n", Modes.gain/10.0);
if (rtlsdr_set_tuner_gain(Modes.dev, Modes.gain) < 0) {
fprintf(stderr, "Error setting tuner gains\n");
return -1;
}
rtlsdr_set_tuner_gain(Modes.dev, Modes.gain);
fprintf(stderr, "Setting gain to: %.2f\n", Modes.gain/10.0);
} else {
fprintf(stderr, "Using automatic gain control.\n");
}
@ -255,7 +293,7 @@ int modesInitRTLSDR(void) {
rtlsdr_set_sample_rate(Modes.dev, Modes.oversample ? MODES_OVERSAMPLE_RATE : MODES_DEFAULT_RATE);
rtlsdr_reset_buffer(Modes.dev);
fprintf(stderr, "Gain reported by device: %.2f\n",
fprintf(stderr, "Gain reported by device: %.2f dB\n",
rtlsdr_get_tuner_gain(Modes.dev)/10.0);
return 0;