From 3611f07ad63cee539f1a618b03d7481791dc3f9d Mon Sep 17 00:00:00 2001
From: Uwe Risse <dg2ycb@gmx.de>
Date: Mon, 5 Feb 2024 16:50:22 +0100
Subject: [PATCH] Enable Tx by double-clicking on a combined message on
 standard FT8 sub-bands is no longer permitted, as 10-bit hash collisions are
 too likely.

---
 widgets/mainwindow.cpp | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/widgets/mainwindow.cpp b/widgets/mainwindow.cpp
index 639dc174a..2a4ca827d 100644
--- a/widgets/mainwindow.cpp
+++ b/widgets/mainwindow.cpp
@@ -5531,8 +5531,31 @@ void MainWindow::doubleClickOnCall(Qt::KeyboardModifiers modifiers)
     return;
   }
   DecodedText message {cursor.block().text().trimmed().left(61).remove("TU; ")};
-  m_bDoubleClicked = true;
-  processMessage (message, modifiers);
+  if(message.string().contains(";") && message.string().contains("<")) {
+    QVector<qint32> ft8Freq = {1840000,3573000,7074000,10136000,14074000,18100000,21074000,24915000,28074000,50313000,70154000};
+    for(int i=0; i<ft8Freq.length()-1; i++) {
+        int kHzdiff=m_freqNominal - ft8Freq[i];
+        if(qAbs(kHzdiff) < 3000 ) {
+        m_bTxTime=false;
+        if (m_auto) auto_tx_mode (false);
+        if (m_tune) stop_tuning();
+        auto const& msg2 = tr("Double-clicking on combined messages\n"
+                              "not allowed on the standard FT8 sub-bands.\n\n"
+                              "First verify that the displayed <callsign>\n"
+                              "is not a decoding artefact.");
+        QTimer::singleShot (0, [=] {               // don't block guiUpdate
+          MessageBox::warning_message (this, tr ("Potential hash collision"), msg2);
+        });
+        break;
+      } else {
+          m_bDoubleClicked = true;
+          processMessage (message, modifiers);
+      }
+    }
+  } else {
+      m_bDoubleClicked = true;
+      processMessage (message, modifiers);
+  }
 }
 
 void MainWindow::processMessage (DecodedText const& message, Qt::KeyboardModifiers modifiers)