From b6652ecfbc36ea44fdd4bf9f6390030c58ee7003 Mon Sep 17 00:00:00 2001
From: f4exb <f4exb06@gmail.com>
Date: Fri, 13 Feb 2026 09:08:50 +0100
Subject: [PATCH] Removed legacy FFT RRC filter

---
 .../demodinmarsat/inmarsatdemodsink.cpp       | 15 ++---------
 .../demodinmarsat/inmarsatdemodsink.h         |  2 --
 sdrbase/dsp/fftfilt.cpp                       | 27 -------------------
 sdrbase/dsp/fftfilt.h                         |  1 -
 4 files changed, 2 insertions(+), 43 deletions(-)

diff --git a/plugins/channelrx/demodinmarsat/inmarsatdemodsink.cpp b/plugins/channelrx/demodinmarsat/inmarsatdemodsink.cpp
index 7eac2f6ca..df5081b50 100644
--- a/plugins/channelrx/demodinmarsat/inmarsatdemodsink.cpp
+++ b/plugins/channelrx/demodinmarsat/inmarsatdemodsink.cpp
@@ -332,8 +332,6 @@ InmarsatDemodSink::InmarsatDemodSink(InmarsatDemod *stdCDemod) :
 {
     m_magsq = 0.0;
 
-    m_rrcFilter = new fftfilt(m_settings.m_rfBandwidth / (float) m_channelSampleRate, RRC_FILTER_SIZE);
-
     m_rrcI.create(m_settings.m_rrcRolloff, 5, SAMPLES_PER_SYMBOL, RootRaisedCosine<Real>::Gain);
     m_rrcQ.create(m_settings.m_rrcRolloff, 5, SAMPLES_PER_SYMBOL, RootRaisedCosine<Real>::Gain);
 
@@ -358,8 +356,6 @@ InmarsatDemodSink::InmarsatDemodSink(InmarsatDemod *stdCDemod) :
 
 InmarsatDemodSink::~InmarsatDemodSink()
 {
-    delete m_rrcFilter;
-    m_rrcFilter = nullptr;
     delete m_equalizer;
     m_equalizer = nullptr;
 }
@@ -473,10 +469,8 @@ void InmarsatDemodSink::processOneSample(Complex &ci)
     // Send signals to scope that are updated for each invocation of this method
     sampleToScopeA(cScaled, magsq, agcZ, m_agc.getGain(), m_agc.getAverage(), cCFO);
 
-    // RRC Matched filter
-    fftfilt::cmplx *rrcFilterOut = nullptr;
-    int n_out = m_rrcFilter->runFilt(cCFO, &rrcFilterOut);
-
+    // Bufferized RRC Matched filter
+    int n_out;
     m_rrcBuffer[m_rrcBufferIndex++] = cCFO;
 
     if (m_rrcBufferIndex == RRC_FILTER_SIZE/2)
@@ -491,7 +485,6 @@ void InmarsatDemodSink::processOneSample(Complex &ci)
 
     for (int i = 0; i < n_out; i++)
     {
-        //Complex rrc = rrcFilterOut[i];
         Complex rrc (m_rrcI.filter(m_rrcBuffer[i].real()), m_rrcQ.filter(m_rrcBuffer[i].imag()));
 
         // Symbol synchronizer
@@ -704,10 +697,6 @@ void InmarsatDemodSink::applySettings(const InmarsatDemodSettings& settings, con
         m_costasLoop.setMinFreq(-freqMax);
     }
 
-    if (settingsKeys.contains("rfBandwidth") || settingsKeys.contains("rrcRolloff") || force) {
-        m_rrcFilter->create_rrc_filter(settings.m_rfBandwidth / (float) m_channelSampleRate, settings.m_rrcRolloff);
-    }
-
     if (settingsKeys.contains("pllBandwidth") || force) {
         m_costasLoop.computeCoefficients(settings.m_pllBW);
     }
diff --git a/plugins/channelrx/demodinmarsat/inmarsatdemodsink.h b/plugins/channelrx/demodinmarsat/inmarsatdemodsink.h
index 6c38b0998..4389fa0ea 100644
--- a/plugins/channelrx/demodinmarsat/inmarsatdemodsink.h
+++ b/plugins/channelrx/demodinmarsat/inmarsatdemodsink.h
@@ -25,7 +25,6 @@
 #include "dsp/channelsamplesink.h"
 #include "dsp/nco.h"
 #include "dsp/interpolator.h"
-#include "dsp/fftfilt.h"
 #include "dsp/fftengine.h"
 #include "dsp/fftwindow.h"
 #include "dsp/costasloop.h"
@@ -213,7 +212,6 @@ private:
     bool m_locked;
 
     static const int RRC_FILTER_SIZE = 256;
-    fftfilt *m_rrcFilter;
     Complex m_rrcBuffer[RRC_FILTER_SIZE];
     RootRaisedCosine<Real> m_rrcI;                       //!< Square root raised cosine filter for I samples
     RootRaisedCosine<Real> m_rrcQ;                       //!< Square root raised cosine filter for Q samples
diff --git a/sdrbase/dsp/fftfilt.cpp b/sdrbase/dsp/fftfilt.cpp
index 5293ee0f5..aa8123c76 100644
--- a/sdrbase/dsp/fftfilt.cpp
+++ b/sdrbase/dsp/fftfilt.cpp
@@ -420,32 +420,6 @@ void fftfilt::create_asym_filter(float fopp, float fin, FFTWindow::Function wf)
     }
 }
 
-// This filter is constructed directly from frequency domain response. Run with runFilt.
-void fftfilt::create_rrc_filter(float fb, float a)
-{
-    std::fill(filter, filter+flen, 0);
-
-    for (int i = 0; i < flen; i++) {
-        filter[i] = frrc(fb, a, i, flen);
-    }
-
-    // normalize the output filter for unity gain
-    float scale = 0, mag;
-    for (int i = 0; i < flen; i++)
-    {
-        mag = abs(filter[i]);
-        if (mag > scale) {
-            scale = mag;
-        }
-    }
-    if (scale != 0)
-    {
-        for (int i = 0; i < flen; i++) {
-            filter[i] /= scale;
-        }
-    }
-}
-
 // test bypass
 int fftfilt::noFilt(const cmplx & in, cmplx **out)
 {
@@ -687,4 +661,3 @@ void sfft::fetch(float *result)
 		*result = itr->bins.real() * itr->bins.real()
                         + itr->bins.imag() * itr->bins.imag();
 }
-
diff --git a/sdrbase/dsp/fftfilt.h b/sdrbase/dsp/fftfilt.h
index 5cd062398..09a0901b5 100644
--- a/sdrbase/dsp/fftfilt.h
+++ b/sdrbase/dsp/fftfilt.h
@@ -52,7 +52,6 @@ public:
     void create_filter(const std::vector<std::pair<float, float>>& limits, bool pass = true); //!< Windowless version
 	void create_dsb_filter(float f2, FFTWindow::Function wf = FFTWindow::Blackman);
     void create_asym_filter(float fopp, float fin, FFTWindow::Function wf = FFTWindow::Blackman); //!< two different filters for in band and opposite band
-    void create_rrc_filter(float fb, float a); //!< root raised cosine. fb is half the band pass
 
 	int noFilt(const cmplx& in, cmplx **out);
 	int runFilt(const cmplx& in, cmplx **out);