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Relax the A/C quiet threshold; this seems to pick up a lot more A/C messages.

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This commit is contained in:
Oliver Jowett 2016-07-24 15:05:52 +01:00
parent 1e5a6fd854
commit a06b13d42a
1 changed files with 3 additions and 2 deletions
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5
demod_2400.c
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@ -528,6 +528,7 @@ void demodulate2400AC(struct mag_buf *mag)
// ----- X1/X2/X3 average noise // ----- X1/X2/X3 average noise
float midpoint = sqrtf(x1x2x3_noise * f1f2_signal); // so that signal/midpoint == midpoint/noise float midpoint = sqrtf(x1x2x3_noise * f1f2_signal); // so that signal/midpoint == midpoint/noise
unsigned quiet_threshold = (unsigned) midpoint;
unsigned noise_threshold = (unsigned) (midpoint * 0.707107 + 0.5); // -3dB from midpoint unsigned noise_threshold = (unsigned) (midpoint * 0.707107 + 0.5); // -3dB from midpoint
unsigned signal_threshold = (unsigned) (midpoint * 1.414214 + 0.5); // +3dB from midpoint unsigned signal_threshold = (unsigned) (midpoint * 1.414214 + 0.5); // +3dB from midpoint
@ -563,8 +564,8 @@ void demodulate2400AC(struct mag_buf *mag)
noisy_bits <<= 1; noisy_bits <<= 1;
// check for excessive noise in the quiet period // check for excessive noise in the quiet period
if (m[sample+2] >= noise_threshold) { if (m[sample+2] >= quiet_threshold) {
//fprintf(stderr, "bit %u was not quiet (%u > %u)\n", bit, m[sample+2], signal_threshold); //fprintf(stderr, "bit %u was not quiet (%u > %u)\n", bit, m[sample+2], quiet_threshold);
noisy_bits |= 1; noisy_bits |= 1;
continue; continue;
} }