From f2df7ad3f075ad848beffa97177e1735277f2c20 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jan=20K=C3=A4berich?= <j.kaeberich@gmx.de>
Date: Wed, 10 Jul 2024 10:05:25 +0200
Subject: [PATCH] Shift TDR output from positive times only to centered around
 zero

---
 Software/PC_Application/LibreVNA-GUI/Traces/Math/tdr.cpp | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/Software/PC_Application/LibreVNA-GUI/Traces/Math/tdr.cpp b/Software/PC_Application/LibreVNA-GUI/Traces/Math/tdr.cpp
index f53b139..20bdc3a 100644
--- a/Software/PC_Application/LibreVNA-GUI/Traces/Math/tdr.cpp
+++ b/Software/PC_Application/LibreVNA-GUI/Traces/Math/tdr.cpp
@@ -323,15 +323,16 @@ void TDRThread::run()
         tdr.window.apply(frequencyDomain);
         Fft::shift(frequencyDomain, true);
 
-        auto fft_bins = frequencyDomain.size();
+        int fft_bins = frequencyDomain.size();
         const double fs = 1.0 / (stepSize * fft_bins);
 
         Fft::transform(frequencyDomain, true);
+        Fft::shift(frequencyDomain, false);
 
         tdr.data.resize(fft_bins, TraceMath::Data());
 
-        for(unsigned int i = 0;i<fft_bins;i++) {
-            tdr.data[i].x = fs * i;
+        for(int i = 0;i<fft_bins;i++) {
+            tdr.data[i].x = fs * (i - fft_bins / 2);
             tdr.data[i].y = frequencyDomain[i] / (double) fft_bins;
         }
         if(tdr.stepResponse && tdr.mode == TDR::Mode::Lowpass) {