From 227245eb94d8bc791c4362137de61f7919f3b9ef Mon Sep 17 00:00:00 2001
From: f4exb <f4exb06@gmail.com>
Date: Sun, 14 Mar 2021 10:54:37 +0100
Subject: [PATCH] DATV: CNR optimization

---
 plugins/channelrx/demoddatv/datvdemodsink.cpp |  4 +--
 plugins/channelrx/demoddatv/leansdr/sdr.h     | 35 +++++++++++++------
 2 files changed, 26 insertions(+), 13 deletions(-)

diff --git a/plugins/channelrx/demoddatv/datvdemodsink.cpp b/plugins/channelrx/demoddatv/datvdemodsink.cpp
index 1baaf4ad8..4eee1bd06 100644
--- a/plugins/channelrx/demoddatv/datvdemodsink.cpp
+++ b/plugins/channelrx/demoddatv/datvdemodsink.cpp
@@ -668,7 +668,7 @@ void DATVDemodSink::InitDATVFramework()
 
     if (m_objCfg.cnr == true)
     {
-        r_cnr = new leansdr::cnr_fft<leansdr::f32>(m_objScheduler, *p_preprocessed, *p_cnr, m_objCfg.Fm/m_objCfg.Fs);
+        r_cnr = new leansdr::cnr_fft<leansdr::f32>(m_objScheduler, *p_preprocessed, *p_cnr, m_objCfg.Fm/m_objCfg.Fs, 1024);
         r_cnr->decimation = decimation(m_objCfg.Fs, 5);  // 5 Hz
     }
 
@@ -1000,7 +1000,7 @@ void DATVDemodSink::InitDATVS2Framework()
 
     if (m_objCfg.cnr == true)
     {
-        r_cnr = new leansdr::cnr_fft<leansdr::f32>(m_objScheduler, *p_preprocessed, *p_cnr, m_objCfg.Fm/m_objCfg.Fs);
+        r_cnr = new leansdr::cnr_fft<leansdr::f32>(m_objScheduler, *p_preprocessed, *p_cnr, m_objCfg.Fm/m_objCfg.Fs, 1024);
         r_cnr->decimation = decimation(m_objCfg.Fs, 5);  // 5 Hz
     }
 
diff --git a/plugins/channelrx/demoddatv/leansdr/sdr.h b/plugins/channelrx/demoddatv/leansdr/sdr.h
index 8c4cce61c..6a101a20f 100644
--- a/plugins/channelrx/demoddatv/leansdr/sdr.h
+++ b/plugins/channelrx/demoddatv/leansdr/sdr.h
@@ -1796,7 +1796,8 @@ struct cnr_fft : runnable
         scheduler *sch,
         pipebuf<complex<T>> &_in,
         pipebuf<float> &_out,
-        float _bandwidth, int nfft = 4096
+        float _bandwidth,
+        int nfft = 4096
     ) :
         runnable(sch, "cnr_fft"),
         bandwidth(_bandwidth),
@@ -1808,6 +1809,8 @@ struct cnr_fft : runnable
         out(_out),
         fft(nfft),
         avgpower(nullptr),
+        data(nullptr),
+        power(nullptr),
         phase(0),
         cslots_ratio(0.2),
         nslots_shift_ratio(0.65),
@@ -1824,6 +1827,12 @@ struct cnr_fft : runnable
         if (avgpower) {
             delete[] avgpower;
         }
+        if (data) {
+            delete[] data;
+        }
+        if (power) {
+            delete[] power;
+        }
     }
 
     void run()
@@ -1850,12 +1859,17 @@ struct cnr_fft : runnable
   private:
     void do_cnr()
     {
+        if (!data) {
+            data = new complex<T>[fft.n];
+        }
+        if (!power) {
+            power = new T[fft.n];
+        }
+
         float center_freq = freq_tap ? *freq_tap * tap_multiplier : 0;
         int icf = floor(center_freq * fft.n + 0.5);
-        complex<T> *data = new complex<T>[fft.n];
         memcpy(data, in.rd(), fft.n * sizeof(data[0]));
         fft.inplace(data, true);
-        T *power = new T[fft.n];
 
         for (int i = 0; i < fft.n; ++i)
             power[i] = data[i].re * data[i].re + data[i].im * data[i].im;
@@ -1867,9 +1881,10 @@ struct cnr_fft : runnable
             memcpy(avgpower, power, fft.n * sizeof(avgpower[0]));
         }
 
-        // Accumulate and low-pass filter
-        for (int i = 0; i < fft.n; ++i)
+        // Accumulate and low-pass filter (exponential averaging)
+        for (int i = 0; i < fft.n; ++i) {
             avgpower[i] = avgpower[i] * (1 - kavg) + power[i] * kavg;
+        }
 
 #if 0
         int bwslots = (bandwidth / 4) * fft.n;
@@ -1888,12 +1903,10 @@ struct cnr_fft : runnable
         int nstart = bandwidth * nslots_shift_ratio * fft.n;
         int nstop = nstart + bandwidth * nslots_ratio * fft.n;
 
-        if (!cbwslots || !nstart || !nstop)
-        {
-            delete[] power;
-            delete[] data;
+        if (!cbwslots || !nstart || !nstop) {
             return;
         }
+
         // Measure carrier+noise in center band
         float c2plusn2 = avgslots(icf - cbwslots, icf + cbwslots);
         // Measure noise left and right of roll-off zones
@@ -1903,8 +1916,6 @@ struct cnr_fft : runnable
         float c2 = c2plusn2 - n2;
         float cnr = (c2 > 0 && n2 > 0) ? 10 * log10f(c2 / n2) : -50;
         out.write(cnr);
-        delete[] power;
-        delete[] data;
     }
 
     float avgslots(int i0, int i1)
@@ -1921,6 +1932,8 @@ struct cnr_fft : runnable
     pipewriter<float> out;
     cfft_engine<T> fft;
     T *avgpower;
+    complex<T> *data;
+    T *power;
     int phase;
     float cslots_ratio;
     float nslots_shift_ratio;