Merge branch 'next' into outputRefactoring

4 files changed, 272 insertions, 9 deletions

diff --git a/src/OfdmGenerator.cpp b/src/OfdmGenerator.cpp
index 915d568..b00d66b 100644
--- a/src/OfdmGenerator.cpp
+++ b/src/OfdmGenerator.cpp
@@ -27,11 +27,8 @@
 #include "OfdmGenerator.h"
 #include "PcDebug.h"
 
-#include <complex>
-#include "fftw3.h"
 #define FFT_TYPE fftwf_complex
 
-#include <stdio.h>
 #include <string.h>
 #include <stdexcept>
 #include <assert.h>
@@ -56,7 +53,10 @@ OfdmGenerator::OfdmGenerator(size_t nbSymbols,
     myCfr(enableCfr),
     myCfrClip(cfrClip),
     myCfrErrorClip(cfrErrorClip),
-    myCfrFft(nullptr)
+    myCfrFft(nullptr),
+    // Initialise the PAPRStats to a few seconds worth of samples
+    myPaprBeforeCFR(nbSymbols * 50),
+    myPaprAfterCFR(nbSymbols * 50)
 {
     PDEBUG("OfdmGenerator::OfdmGenerator(%zu, %zu, %zu, %s) @ %p\n",
             nbSymbols, nbCarriers, spacing, inverse ? "true" : "false", this);
@@ -71,6 +71,7 @@ OfdmGenerator::OfdmGenerator(size_t nbSymbols,
     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)");
+    RC_ADD_PARAMETER(papr, "PAPR measurements (before CFR, after CFR)");
 
     if (inverse) {
         myPosDst = (nbCarriers & 1 ? 0 : 1);
@@ -186,6 +187,14 @@ int OfdmGenerator::process(Buffer* const dataIn, Buffer* dataOut)
     // For performance reasons, do not calculate MER for every symbol.
     myMERCalcIndex = (myMERCalcIndex + 1) % myNbSymbols;
 
+    // The PAPRStats' clear() is not threadsafe, do not access it
+    // from the RC functions.
+    if (myPaprClearRequest.load()) {
+        myPaprBeforeCFR.clear();
+        myPaprAfterCFR.clear();
+        myPaprClearRequest.store(false);
+    }
+
     for (size_t i = 0; i < myNbSymbols; ++i) {
         myFftIn[0][0] = 0;
         myFftIn[0][1] = 0;
@@ -203,19 +212,25 @@ int OfdmGenerator::process(Buffer* const dataIn, Buffer* dataOut)
 
         fftwf_execute(myFftPlan); // IFFT from myFftIn to myFftOut
 
+        complexf *symbol = reinterpret_cast<complexf*>(myFftOut);
+        myPaprBeforeCFR.process_block(symbol, mySpacing);
+
         if (myCfr) {
             if (myMERCalcIndex == i) {
                 before_cfr.resize(mySpacing);
                 memcpy(before_cfr.data(), myFftOut, mySpacing * sizeof(FFT_TYPE));
             }
 
-            complexf *symbol = reinterpret_cast<complexf*>(myFftOut);
             /* cfr_one_iteration runs the myFftPlan again at the end, and
              * therefore writes the output data to myFftOut.
              */
             const auto stat = cfr_one_iteration(symbol, reference.data());
 
             // i == 0 always zero power, so the MER ends up being NaN
+            if (i > 0) {
+                myPaprAfterCFR.process_block(symbol, mySpacing);
+            }
+
             if (i > 0 and myMERCalcIndex == i) {
                 /* MER definition, ETSI ETR 290, Annex C
                  *
@@ -351,15 +366,18 @@ void OfdmGenerator::set_parameter(const std::string& parameter,
 
     if (parameter == "cfr") {
         ss >> myCfr;
+        myPaprClearRequest.store(true);
     }
     else if (parameter == "clip") {
         ss >> myCfrClip;
+        myPaprClearRequest.store(true);
     }
     else if (parameter == "errorclip") {
         ss >> myCfrErrorClip;
+        myPaprClearRequest.store(true);
     }
-    else if (parameter == "clip_stats") {
-        throw ParameterError("Parameter 'clip_stats' is read-only");
+    else if (parameter == "clip_stats" or parameter == "papr") {
+        throw ParameterError("Parameter '" + parameter + "' is read-only");
     }
     else {
         stringstream ss_err;
@@ -406,6 +424,15 @@ const std::string OfdmGenerator::get_parameter(const std::string& parameter) con
                 "MER after CFR: " << avg_mer << " dB";
         }
     }
+    else if (parameter == "papr") {
+        const double papr_before = myPaprBeforeCFR.calculate_papr();
+        const double papr_after = myPaprAfterCFR.calculate_papr();
+
+        ss << "PAPR [dB]: " << std::fixed <<
+            (papr_before == 0 ? string("N/A") : to_string(papr_before)) <<
+            ", " <<
+            (papr_after == 0 ? string("N/A") : to_string(papr_after));
+    }
     else {
         ss << "Parameter '" << parameter <<
             "' is not exported by controllable " << get_rc_name();
diff --git a/src/OfdmGenerator.h b/src/OfdmGenerator.h
index 008d84e..cccccf5 100644
--- a/src/OfdmGenerator.h
+++ b/src/OfdmGenerator.h
@@ -30,13 +30,14 @@
 #   include "config.h"
 #endif
 
-#include "porting.h"
 #include "ModPlugin.h"
 #include "RemoteControl.h"
+#include "PAPRStats.h"
 #include "fftw3.h"
-#include <sys/types.h>
+#include <cstddef>
 #include <vector>
 #include <complex>
+#include <atomic>
 
 typedef std::complex<float> complexf;
 
@@ -102,6 +103,11 @@ class OfdmGenerator : public ModCodec, public RemoteControllable
         std::deque<double> myClipRatios;
         std::deque<double> myErrorClipRatios;
 
+        // Measure PAPR before and after CFR
+        PAPRStats myPaprBeforeCFR;
+        PAPRStats myPaprAfterCFR;
+        std::atomic<bool> myPaprClearRequest;
+
         size_t myMERCalcIndex = 0;
         std::deque<double> myMERs;
 };
diff --git a/src/PAPRStats.cpp b/src/PAPRStats.cpp
new file mode 100644
index 0000000..1a72238
--- /dev/null
+++ b/src/PAPRStats.cpp
@@ -0,0 +1,152 @@
+/*
+   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Her Majesty
+   the Queen in Right of Canada (Communications Research Center Canada)
+
+   Copyright (C) 2017
+   Matthias P. Braendli, matthias.braendli@mpb.li
+
+    http://opendigitalradio.org
+ */
+/*
+   This file is part of ODR-DabMod.
+
+   ODR-DabMod is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as
+   published by the Free Software Foundation, either version 3 of the
+   License, or (at your option) any later version.
+
+   ODR-DabMod is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with ODR-DabMod.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "PAPRStats.h"
+#include <numeric>
+#include <cmath>
+#if defined(TEST)
+/* compile with g++ -std=c++11 -Wall -DTEST PAPRStats.cpp -o paprtest */
+#  include <iostream>
+#endif
+
+
+PAPRStats::PAPRStats(size_t num_blocks_to_accumulate) :
+    m_num_blocks_to_accumulate(num_blocks_to_accumulate)
+{
+}
+
+void PAPRStats::process_block(const complexf* data, size_t data_len)
+{
+    double norm_peak = 0;
+    double rms2 = 0;
+
+    for (size_t i = 0; i < data_len; i++) {
+        const double x_norm = std::norm(data[i]);
+
+        if (x_norm > norm_peak) {
+            norm_peak = x_norm;
+        }
+
+        rms2 += x_norm;
+    }
+
+    rms2 /= data_len;
+
+#if defined(TEST)
+    std::cerr << "Accumulating peak " << norm_peak <<
+        " rms2 " << rms2 << std::endl;
+#endif
+
+    m_squared_peaks.push_back(norm_peak);
+    m_squared_mean.push_back(rms2);
+
+    if (m_squared_mean.size() > m_num_blocks_to_accumulate) {
+        m_squared_mean.pop_front();
+        m_squared_peaks.pop_front();
+    }
+}
+
+double PAPRStats::calculate_papr() const
+{
+    if (m_squared_mean.size() < m_num_blocks_to_accumulate) {
+        return 0;
+    }
+
+    if (m_squared_mean.size() != m_squared_peaks.size()) {
+        throw std::logic_error("Invalid PAPR measurement sizes");
+    }
+
+    double peak = 0;
+    double rms2 = 0;
+    for (size_t i = 0; i < m_squared_peaks.size(); i++) {
+        if (m_squared_peaks[i] > peak) {
+            peak = m_squared_peaks[i];
+        }
+
+        rms2 += m_squared_mean[i];
+    }
+
+    // This assumes all blocks given to process have the same length
+    rms2 /= m_squared_peaks.size();
+
+#if defined(TEST)
+    std::cerr << "Calculate peak " << peak <<
+        " rms2 " << rms2 << std::endl;
+#endif
+
+    return 10.0 * std::log10(peak / rms2);
+}
+
+void PAPRStats::clear()
+{
+    m_squared_peaks.clear();
+    m_squared_mean.clear();
+}
+
+#if defined(TEST)
+/* Test python code:
+import numpy as np
+vec = 0.5 * np.exp(np.complex(0, 0.3) * np.arange(40))
+vec[26] = 10.0 * vec[26]
+rms = np.mean(vec * np.conj(vec)).real
+peak = np.amax(vec * np.conj(vec)).real
+print("rms {}".format(rms))
+print("peak {}".format(peak))
+print(10. * np.log10(peak / rms))
+*/
+int main(int argc, char **argv)
+{
+    using namespace std;
+    vector<complexf> vec(40);
+
+    for (size_t i = 0; i < vec.size(); i++) {
+        vec[i] = polar(0.5, 0.3 * i);
+        if (i == 26) {
+            vec[i] *= 10;
+        }
+        cout << " " << vec[i];
+    }
+    cout << endl;
+
+    PAPRStats stats(4);
+
+    for (size_t i = 0; i < 3; i++) {
+        stats.process_block(vec.data(), vec.size());
+    }
+
+    const auto papr0 = stats.calculate_papr();
+    if (papr0 != 0) {
+        cerr << "Expected 0, got " << papr0 << endl;
+    }
+
+    stats.process_block(vec.data(), vec.size());
+
+    const auto papr1 = stats.calculate_papr();
+    cout << "PAPR = " << papr1 << " dB" << endl;
+
+}
+
+#endif
diff --git a/src/PAPRStats.h b/src/PAPRStats.h
new file mode 100644
index 0000000..86ad8b0
--- /dev/null
+++ b/src/PAPRStats.h
@@ -0,0 +1,78 @@
+/*
+   Copyright (C) 2005, 2006, 2007, 2008, 2009, 2010, 2011 Her Majesty
+   the Queen in Right of Canada (Communications Research Center Canada)
+
+   Copyright (C) 2017
+   Matthias P. Braendli, matthias.braendli@mpb.li
+
+    http://opendigitalradio.org
+ */
+/*
+   This file is part of ODR-DabMod.
+
+   ODR-DabMod is free software: you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as
+   published by the Free Software Foundation, either version 3 of the
+   License, or (at your option) any later version.
+
+   ODR-DabMod is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with ODR-DabMod.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#ifdef HAVE_CONFIG_H
+#   include "config.h"
+#endif
+
+#include <cstddef>
+#include <vector>
+#include <deque>
+#include <complex>
+
+typedef std::complex<float> complexf;
+
+/* Helper class to calculate Peak-to-average-power ratio.
+ * Definition of PAPR:
+ *
+ * PAPR_dB = 10 * log_10 ( abs(x_peak)^2 / x_rms^2 )
+ *
+ * with abs(x_peak) the peak amplitude of the signal, and
+ * x_rms the Root Mean Squared.
+ *
+ * x_rms^2 = 1/n * Sum abs(x_n)^2
+ *         = 1/n * Sum norm(x_n)
+ *
+ * Given that peaks are rare in a DAB signal, we want to accumulate
+ * several seconds worth of samples to do our calculation.
+ */
+class PAPRStats
+{
+    public:
+        PAPRStats(size_t num_blocks_to_accumulate);
+
+        /* Push in a new block of samples to measure. calculate_papr()
+         * assumes all blocks have the same size.
+         */
+        void process_block(const complexf* data, size_t data_len);
+
+        /* Returns PAPR in dB if enough blocks were processed, or
+         * 0 otherwise.
+         */
+        double calculate_papr(void) const;
+
+        void clear(void);
+
+    private:
+        size_t m_num_blocks_to_accumulate;
+        std::deque<double> m_squared_peaks;
+        std::deque<double> m_squared_mean;
+};
+
+
+