diff options
Diffstat (limited to 'Transceiver52M/sigProcLib.cpp')
| -rw-r--r-- | Transceiver52M/sigProcLib.cpp | 46 |
1 files changed, 31 insertions, 15 deletions
diff --git a/Transceiver52M/sigProcLib.cpp b/Transceiver52M/sigProcLib.cpp index 9d8410b..42b4e6e 100644 --- a/Transceiver52M/sigProcLib.cpp +++ b/Transceiver52M/sigProcLib.cpp @@ -28,6 +28,7 @@ #include "sigProcLib.h" #include "GSMCommon.h" +#include "Logger.h" extern "C" { #include "convolve.h" @@ -1372,16 +1373,17 @@ static int detectBurst(signalVector &burst, return 1; } -static int detectClipping(signalVector &burst, float thresh) +static float maxAmplitude(signalVector &burst) { - for (size_t i = 0; i < burst.size(); i++) { - if (fabs(burst[i].real()) > thresh) - return 1; - if (fabs(burst[i].imag()) > thresh) - return 1; - } - - return 0; + float max = 0.0; + for (size_t i = 0; i < burst.size(); i++) { + if (fabs(burst[i].real()) > max) + max = fabs(burst[i].real()); + if (fabs(burst[i].imag()) > max) + max = fabs(burst[i].imag()); + } + + return max; } /* @@ -1399,6 +1401,7 @@ int detectRACHBurst(signalVector &rxBurst, float *toa) { int rc, start, target, head, tail, len; + bool clipping = false; float _toa; complex _amp; signalVector *corr; @@ -1407,8 +1410,14 @@ int detectRACHBurst(signalVector &rxBurst, if ((sps != 1) && (sps != 4)) return -SIGERR_UNSUPPORTED; - if (detectClipping(rxBurst, CLIP_THRESH)) - return -SIGERR_CLIP; + // Detect potential clipping + // We still may be able to demod the burst, so we'll give it a try + // and only report clipping if we can't demod. + float maxAmpl = maxAmplitude(rxBurst); + if (maxAmpl > CLIP_THRESH) { + LOG(DEBUG) << "max burst amplitude: " << maxAmpl << " is above the clipping threshold: " << CLIP_THRESH << std::endl; + clipping = true; + } target = 8 + 40; head = 4; @@ -1430,7 +1439,7 @@ int detectRACHBurst(signalVector &rxBurst, *amp = 0.0f; if (toa) *toa = 0.0f; - return 0; + return clipping?-SIGERR_CLIP:SIGERR_NONE; } /* Subtract forward search bits from delay */ @@ -1455,6 +1464,7 @@ int analyzeTrafficBurst(signalVector &rxBurst, unsigned tsc, float thresh, bool chan_req, signalVector **chan, float *chan_offset) { int rc, start, target, head, tail, len; + bool clipping = false; complex _amp; float _toa; signalVector *corr; @@ -1463,8 +1473,14 @@ int analyzeTrafficBurst(signalVector &rxBurst, unsigned tsc, float thresh, if ((tsc < 0) || (tsc > 7) || ((sps != 1) && (sps != 4))) return -SIGERR_UNSUPPORTED; - if (detectClipping(rxBurst, CLIP_THRESH)) - return -SIGERR_CLIP; + // Detect potential clipping + // We still may be able to demod the burst, so we'll give it a try + // and only report clipping if we can't demod. + float maxAmpl = maxAmplitude(rxBurst); + if (maxAmpl > CLIP_THRESH) { + LOG(DEBUG) << "max burst amplitude: " << maxAmpl << " is above the clipping threshold: " << CLIP_THRESH << std::endl; + clipping = true; + } target = 3 + 58 + 16 + 5; head = 4; @@ -1486,7 +1502,7 @@ int analyzeTrafficBurst(signalVector &rxBurst, unsigned tsc, float thresh, *amp = 0.0f; if (toa) *toa = 0.0f; - return 0; + return clipping?-SIGERR_CLIP:SIGERR_NONE; } /* Subtract forward search bits from delay */ |