diff options
| -rw-r--r-- | doc/example.ini | 7 | ||||
| -rw-r--r-- | src/OfdmGenerator.cpp | 71 | ||||
| -rw-r--r-- | src/OfdmGenerator.h | 14 |
3 files changed, 71 insertions, 21 deletions
diff --git a/doc/example.ini b/doc/example.ini index 512e196..21f15ea 100644 --- a/doc/example.ini +++ b/doc/example.ini @@ -127,16 +127,17 @@ dac_clk_rate=0 ; and ;dac_clk_rate=128000000 -; Settings for crest factor reduction +; Settings for crest factor reduction. Statistics for ratio of +; samples that were clipped are available through the RC. [cfr] enable=0 ; At what amplitude the signal should be clipped -clip=1.0 +clip=70.0 ; How much to clip the error signal used to compensate the effect ; of clipping -error_clip=1.0 +error_clip=0.05 [firfilter] ; The FIR Filter can be used to create a better spectral quality. diff --git a/src/OfdmGenerator.cpp b/src/OfdmGenerator.cpp index 8f5d8a0..4d76dbc 100644 --- a/src/OfdmGenerator.cpp +++ b/src/OfdmGenerator.cpp @@ -36,7 +36,9 @@ #include <stdexcept> #include <assert.h> #include <string> +#include <numeric> +static const size_t MAX_CLIP_STATS = 10; OfdmGenerator::OfdmGenerator(size_t nbSymbols, size_t nbCarriers, @@ -68,6 +70,7 @@ OfdmGenerator::OfdmGenerator(size_t nbSymbols, RC_ADD_PARAMETER(cfr, "Enable crest factor reduction"); RC_ADD_PARAMETER(clip, "CFR: Clip to amplitude"); RC_ADD_PARAMETER(errorclip, "CFR: Limit error"); + RC_ADD_PARAMETER(clip_stats, "CFR: statistics (clip ratio, errorclip ratio)"); if (inverse) { myPosDst = (nbCarriers & 1 ? 0 : 1); @@ -170,13 +173,13 @@ int OfdmGenerator::process(Buffer* const dataIn, Buffer* dataOut) "OfdmGenerator::process output size not valid!"); } - myNumClip = 0; - myNumErrorClip = 0; - // It is not guaranteed that fftw keeps the FFT input vector intact. // That's why we copy it to the reference. std::vector<complexf> reference; + size_t num_clip = 0; + size_t num_error_clip = 0; + for (size_t i = 0; i < myNbSymbols; ++i) { myFftIn[0][0] = 0; myFftIn[0][1] = 0; @@ -196,7 +199,9 @@ int OfdmGenerator::process(Buffer* const dataIn, Buffer* dataOut) if (myCfr) { complexf *symbol = reinterpret_cast<complexf*>(myFftOut); - cfr_one_iteration(symbol, reference.data()); + const auto stat = cfr_one_iteration(symbol, reference.data()); + num_clip += stat.clip_count; + num_error_clip += stat.errclip_count; } memcpy(out, myFftOut, mySpacing * sizeof(FFT_TYPE)); @@ -206,19 +211,35 @@ int OfdmGenerator::process(Buffer* const dataIn, Buffer* dataOut) } if (myCfr) { - etiLog.level(debug) << "CFR: " << myNumClip << " clipped, " << - myNumErrorClip << " err clipped"; + std::lock_guard<std::mutex> lock(myCfrRcMutex); + + const double num_samps = myNbSymbols * mySpacing; + const double clip_ratio = (double)num_clip / num_samps; + + myClipRatios.push_back(clip_ratio); + while (myClipRatios.size() > MAX_CLIP_STATS) { + myClipRatios.pop_front(); + } + + const double errclip_ratio = (double)num_error_clip / num_samps; + myErrorClipRatios.push_back(errclip_ratio); + while (myErrorClipRatios.size() > MAX_CLIP_STATS) { + myErrorClipRatios.pop_front(); + } } return sizeOut; } -void OfdmGenerator::cfr_one_iteration(complexf *symbol, const complexf *reference) +OfdmGenerator::cfr_iter_stat_t OfdmGenerator::cfr_one_iteration( + complexf *symbol, const complexf *reference) { // use std::norm instead of std::abs to avoid calculating the // square roots const float clip_squared = myCfrClip * myCfrClip; + OfdmGenerator::cfr_iter_stat_t ret; + // Clip for (size_t i = 0; i < mySpacing; i++) { const float mag_squared = std::norm(symbol[i]); @@ -228,7 +249,7 @@ void OfdmGenerator::cfr_one_iteration(complexf *symbol, const complexf *referenc // = x * sqrt(clip_squared) / sqrt(mag_squared) // = x * sqrt(clip_squared / mag_squared) symbol[i] *= std::sqrt(clip_squared / mag_squared); - myNumClip++; + ret.clip_count++; } } @@ -245,8 +266,8 @@ void OfdmGenerator::cfr_one_iteration(complexf *symbol, const complexf *referenc std::vector<float> error_norm(mySpacing); for (size_t i = 0; i < mySpacing; i++) { - // FFTW computes an unnormalised trasform, i.e. a FFT-IFFT pair - // or vice-versa give back the original vector scaled by a factor + // FFTW computes an unnormalised transform, i.e. a FFT-IFFT pair + // or vice-versa gives back the original vector scaled by a factor // FFT-size. Because we're comparing our constellation point // (calculated with IFFT-clip-FFT) against reference (input to // the IFFT), we need to divide by our FFT size. @@ -260,7 +281,7 @@ void OfdmGenerator::cfr_one_iteration(complexf *symbol, const complexf *referenc if (mag_squared > err_clip_squared) { error *= std::sqrt(err_clip_squared / mag_squared); - myNumErrorClip++; + ret.errclip_count++; } // Update the input to the FFT directly to avoid another copy for the @@ -269,12 +290,10 @@ void OfdmGenerator::cfr_one_iteration(complexf *symbol, const complexf *referenc fft_in[i] = constellation_point + error; } - auto minmax = std::minmax_element(error_norm.begin(), error_norm.end()); - etiLog.level(debug) << "err min: " << std::sqrt(*minmax.first) - << " max: " << std::sqrt(*minmax.second); - // Run our error-compensated symbol through the IFFT again fftwf_execute(myFftPlan); // IFFT from myFftIn to myFftOut + + return ret; } @@ -294,6 +313,9 @@ void OfdmGenerator::set_parameter(const std::string& parameter, else if (parameter == "errorclip") { ss >> myCfrErrorClip; } + else if (parameter == "clip_stats") { + throw ParameterError("Parameter 'clip_stats' is read-only"); + } else { stringstream ss; ss << "Parameter '" << parameter @@ -315,6 +337,25 @@ const std::string OfdmGenerator::get_parameter(const std::string& parameter) con else if (parameter == "errorclip") { ss << std::fixed << myCfrErrorClip; } + else if (parameter == "clip_stats") { + std::lock_guard<std::mutex> lock(myCfrRcMutex); + if (myClipRatios.empty() or myErrorClipRatios.empty()) { + ss << "No stats available"; + } + else { + const double avg_clip_ratio = + std::accumulate(myClipRatios.begin(), myClipRatios.end(), 0.0) / + myClipRatios.size(); + + const double avg_errclip_ratio = + std::accumulate(myErrorClipRatios.begin(), myErrorClipRatios.end(), 0.0) / + myErrorClipRatios.size(); + + ss << "Statistics : " << std::fixed << + avg_clip_ratio * 100 << "%"" samples clipped, " << + avg_errclip_ratio * 100 << "%"" errors clipped"; + } + } else { ss << "Parameter '" << parameter << "' is not exported by controllable " << get_rc_name(); diff --git a/src/OfdmGenerator.h b/src/OfdmGenerator.h index ad39f5b..9ac0387 100644 --- a/src/OfdmGenerator.h +++ b/src/OfdmGenerator.h @@ -68,7 +68,13 @@ class OfdmGenerator : public ModCodec, public RemoteControllable const std::string& parameter) const override; protected: - void cfr_one_iteration(complexf *symbol, const complexf *reference); + struct cfr_iter_stat_t { + size_t clip_count = 0; + size_t errclip_count = 0; + }; + + cfr_iter_stat_t cfr_one_iteration( + complexf *symbol, const complexf *reference); fftwf_plan myFftPlan; fftwf_complex *myFftIn, *myFftOut; @@ -85,14 +91,16 @@ class OfdmGenerator : public ModCodec, public RemoteControllable unsigned myZeroSize; bool myCfr; // Whether to enable crest factor reduction + mutable std::mutex myCfrRcMutex; float myCfrClip; float myCfrErrorClip; fftwf_plan myCfrFft; fftwf_complex *myCfrPostClip; fftwf_complex *myCfrPostFft; - size_t myNumClip; - size_t myNumErrorClip; + // Statistics for CFR + std::deque<double> myClipRatios; + std::deque<double> myErrorClipRatios; }; |