diff --git a/main.cpp b/main.cpp
index 4c30f615c..dec9ba7de 100644
--- a/main.cpp
+++ b/main.cpp
@@ -7,6 +7,7 @@
 #include <fftw3.h>
 
 #include <QSharedMemory>
+#include <QProcessEnvironment>
 #include <QTemporaryFile>
 #include <QDateTime>
 #include <QApplication>
@@ -108,6 +109,8 @@ int main(int argc, char *argv[])
   // Multiple instances communicate with jt9 via this
   QSharedMemory mem_jt9;
 
+  auto const env = QProcessEnvironment::systemEnvironment ();
+
   QApplication a(argc, argv);
   try
     {
@@ -411,7 +414,7 @@ int main(int argc, char *argv[])
           }
 
           // run the application UI
-          MainWindow w(temp_dir, multiple, &multi_settings, &mem_jt9, downSampleFactor, &splash);
+          MainWindow w(temp_dir, multiple, &multi_settings, &mem_jt9, downSampleFactor, &splash, env);
           w.show();
           splash.raise ();
           QObject::connect (&a, SIGNAL (lastWindowClosed()), &a, SLOT (quit()));
diff --git a/widgets/astro.h b/widgets/astro.h
index a2474072f..2b544872c 100644
--- a/widgets/astro.h
+++ b/widgets/astro.h
@@ -2,6 +2,8 @@
 #ifndef ASTRO_H
 #define ASTRO_H
 
+#include <utility>
+
 #include <QDialog>
 #include <QScopedPointer>
 
@@ -34,9 +36,17 @@ public:
     Correction (Correction const&) = default;
     Correction& operator = (Correction const&) = default;
 
+    // testing facility used to test Doppler corrections on
+    // terrestrial links
+    void reverse ()
+    {
+      std::swap (rx, tx);
+    }
+
     FrequencyDelta rx;
     FrequencyDelta tx;
   };
+
   Correction astroUpdate(QDateTime const& t,
                          QString const& mygrid,
                          QString const& hisgrid,
diff --git a/widgets/mainwindow.cpp b/widgets/mainwindow.cpp
index d20331bc4..a7eb780da 100644
--- a/widgets/mainwindow.cpp
+++ b/widgets/mainwindow.cpp
@@ -13,6 +13,7 @@
 #include <QStringListModel>
 #include <QSettings>
 #include <QKeyEvent>
+#include <QProcessEnvironment>
 #include <QSharedMemory>
 #include <QFileDialog>
 #include <QTextBlock>
@@ -233,8 +234,9 @@ namespace
 MainWindow::MainWindow(QDir const& temp_directory, bool multiple,
                        MultiSettings * multi_settings, QSharedMemory *shdmem,
                        unsigned downSampleFactor,
-                       QSplashScreen * splash, QWidget *parent) :
+                       QSplashScreen * splash, QProcessEnvironment const& env, QWidget *parent) :
   QMainWindow(parent),
+  m_env {env},
   m_network_manager {this},
   m_valid {true},
   m_splash {splash},
@@ -266,6 +268,7 @@ MainWindow::MainWindow(QDir const& temp_directory, bool multiple,
   m_secBandChanged {0},
   m_freqNominal {0},
   m_freqTxNominal {0},
+  m_reverse_Doppler {"1" == env.value ("WSJT_REVERSE_DOPPLER", "0")},
   m_s6 {0.},
   m_tRemaining {0.},
   m_TRperiod {60.0},
@@ -926,9 +929,9 @@ MainWindow::MainWindow(QDir const& temp_directory, bool multiple,
       , "-a", QDir::toNativeSeparators (m_config.writeable_data_dir ().absolutePath ())
       , "-t", QDir::toNativeSeparators (m_config.temp_dir ().absolutePath ())
       };
-  QProcessEnvironment env {QProcessEnvironment::systemEnvironment ()};
-  env.insert ("OMP_STACKSIZE", "4M");
-  proc_jt9.setProcessEnvironment (env);
+  QProcessEnvironment new_env {m_env};
+  new_env.insert ("OMP_STACKSIZE", "4M");
+  proc_jt9.setProcessEnvironment (new_env);
   proc_jt9.start(QDir::toNativeSeparators (m_appDir) + QDir::separator () +
           "jt9", jt9_args, QIODevice::ReadWrite | QIODevice::Unbuffered);
 
@@ -4227,7 +4230,15 @@ void MainWindow::guiUpdate()
     transmitDisplay (true);
     statusUpdate ();
   }
-  if(!m_btxok && m_btxok0 && g_iptt==1) stopTx();
+  if(!m_btxok && m_btxok0 && g_iptt==1)
+    {
+      stopTx();
+      if ("1" == m_env.value ("WSJT_TX_BOTH", "0"))
+        {
+          m_txFirst = !m_txFirst;
+          ui->txFirstCheckBox->setChecked (m_txFirst);
+        }
+    }
 
   if(m_startAnother) {
     if(m_mode=="MSK144") {
@@ -8193,6 +8204,10 @@ void MainWindow::astroUpdate ()
               correction.tx = correction.tx / 10 * 10;
             }
           m_astroCorrection = correction;
+          if (m_reverse_Doppler)
+            {
+              m_astroCorrection.reverse ();
+            }
         }
       else
         {
diff --git a/widgets/mainwindow.h b/widgets/mainwindow.h
index 7a8537d03..272664e78 100644
--- a/widgets/mainwindow.h
+++ b/widgets/mainwindow.h
@@ -63,6 +63,7 @@ namespace Ui {
   class MainWindow;
 }
 
+class QProcessEnvironment;
 class QSharedMemory;
 class QSplashScreen;
 class QSettings;
@@ -103,7 +104,7 @@ public:
 
   explicit MainWindow(QDir const& temp_directory, bool multiple, MultiSettings *,
                       QSharedMemory *shdmem, unsigned downSampleFactor,
-                      QSplashScreen *,
+                      QSplashScreen *, QProcessEnvironment const&,
                       QWidget *parent = nullptr);
   ~MainWindow();
 
@@ -356,6 +357,7 @@ private:
   void setColorHighlighting();
   void chkFT4();
 
+  QProcessEnvironment const& m_env;
   NetworkAccessManager m_network_manager;
   bool m_valid;
   QSplashScreen * m_splash;
@@ -407,6 +409,7 @@ private:
   Frequency m_freqNominal;
   Frequency m_freqTxNominal;
   Astro::Correction m_astroCorrection;
+  bool m_reverse_Doppler;
 
   double  m_s6;
   double  m_tRemaining;