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Make signalLevel represent the SNR in dB, rather than a somewhat arbitrary amplitude value.

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Include SNR values when dumping message contents.
This commit is contained in:
Oliver Jowett 2014-09-15 02:49:11 +01:00
parent 0378620445
commit 2e45a59986
4 changed files with 33 additions and 27 deletions
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7
mode_ac.c
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@ -144,6 +144,7 @@ int detectModeA(uint16_t *m, struct modesMessage *mm)
int F1_sig, F1_noise;
int F2_sig, F2_noise;
int fSig, fNoise, fLevel, fLoLo;
float snr;
// m[0] contains the energy from 0 -> 499 nS
// m[1] contains the energy from 500 -> 999 nS
@ -306,8 +307,8 @@ int detectModeA(uint16_t *m, struct modesMessage *mm)
if ((ModeABits < 3) || (ModeABits & 0xFFFF8808) || (ModeAErrs) )
{return (ModeABits = 0);}
fSig = (fSig + 0x7F) >> 8;
mm->signalLevel = ((fSig < 255) ? fSig : 255);
snr = 5 * 20.0 * log10f((float)(fSig + fNoise + 365) / (fNoise + 365)); // 365 to adjust for magnitude value offset
mm->signalLevel = ((snr < 255) ? (uint8_t)round(snr) : 255);
return ModeABits;
}
@ -383,4 +384,4 @@ void decodeModeAMessage(struct modesMessage *mm, int ModeA)
}
//
// ===================== Mode A/C detection and decoding ===================
//
//