diff --git a/getfile.cpp b/getfile.cpp
index 4f181e5f7..1568a4a91 100644
--- a/getfile.cpp
+++ b/getfile.cpp
@@ -6,9 +6,9 @@
 
 extern qint16 id[4*60*96000];
 
-void getfile(QString fname, bool xpol, int dbDgrd)
+void getfile(QString fname, bool xpol, int dbDgrd, int nfast)
 {
-  int npts=2*52*96000;
+  int npts=2*52*96000/nfast;
   if(xpol) npts=2*npts;
 
 // Degrade S/N by dbDgrd dB -- for tests only!!
@@ -52,9 +52,9 @@ void getfile(QString fname, bool xpol, int dbDgrd)
   }
 }
 
-void savetf2(QString fname, bool xpol)
+void savetf2(QString fname, bool xpol, int nfast)
 {
-  int npts=2*52*96000;
+  int npts=2*52*96000/nfast;
   if(xpol) npts=2*npts;
 
   qint16* buf=(qint16*)malloc(2*npts);
diff --git a/getfile.h b/getfile.h
index 796c31e5c..abb3f89bc 100644
--- a/getfile.h
+++ b/getfile.h
@@ -5,8 +5,8 @@
 #include <QDebug>
 #include "commons.h"
 
-void getfile(QString fname, bool xpol, int dbDgrd);
-void savetf2(QString fname, bool xpol);
+void getfile(QString fname, bool xpol, int dbDgrd, int nfast);
+void savetf2(QString fname, bool xpol, int nfast);
 float gran();
 
 #endif // GETFILE_H
diff --git a/libm65/mapsim.f90 b/libm65/mapsim.f90
index 8f2225d49..7da83ac07 100644
--- a/libm65/mapsim.f90
+++ b/libm65/mapsim.f90
@@ -53,6 +53,7 @@ program mapsim
   if(mode(1:1).eq.'C') mode65=4
   nfast=1
   if(mode(2:2).eq.'2') nfast=2
+  npts=NMAX/nfast
   open(12,file='msgs.txt',status='old')
 
   write(*,1000)
@@ -67,7 +68,7 @@ program mapsim
      open(10,file=fname//'.iq',access='stream',status='unknown')
      open(11,file=fname//'.tf2',access='stream',status='unknown')
 
-     call noisegen(d4,NMAX)                      !Generate Gaussuian noise
+     call noisegen(d4,npts)                      !Generate Gaussuian noise
 
      if(msg0.ne.'                      ') then
         call cgen65(message,mode65,nfast,samfac,nsendingsh,msgsent,cwave,nwave)
@@ -113,7 +114,7 @@ program mapsim
         enddo
      enddo
 
-     do i=1,NMAX
+     do i=1,npts
         id4(1,i)=nint(rms*d4(1,i))
         id4(2,i)=nint(rms*d4(2,i))
         id4(3,i)=nint(rms*d4(3,i))
@@ -122,8 +123,8 @@ program mapsim
         id2(2,i)=id4(2,i)
      enddo
 
-     write(10) fcenter,id2
-     write(11) fcenter,id4
+     write(10) fcenter,id2(1:2,1:npts)
+     write(11) fcenter,id4(1:4,1:npts)
      close(10)
      close(11)
   enddo
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 1bdab40ba..97a26141c 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -57,6 +57,8 @@ MainWindow::MainWindow(QWidget *parent) :
   ui->actionJT65A->setActionGroup(modeGroup);
   ui->actionJT65B->setActionGroup(modeGroup);
   ui->actionJT65C->setActionGroup(modeGroup);
+  ui->actionJT65B2->setActionGroup(modeGroup);
+  ui->actionJT65C2->setActionGroup(modeGroup);
 
   QActionGroup* saveGroup = new QActionGroup(this);
   ui->actionSave_all->setActionGroup(saveGroup);
@@ -199,6 +201,8 @@ MainWindow::MainWindow(QWidget *parent) :
   if(m_mode=="JT65A") on_actionJT65A_triggered();
   if(m_mode=="JT65B") on_actionJT65B_triggered();
   if(m_mode=="JT65C") on_actionJT65C_triggered();
+  if(m_mode=="JT65B2") on_actionJT65B2_triggered();
+  if(m_mode=="JT65C2") on_actionJT65C2_triggered();
 
   future1 = new QFuture<void>;
   watcher1 = new QFutureWatcher<void>;
@@ -461,7 +465,7 @@ void MainWindow::dataSink(int k)
   static int n=0;
   static int ihsym=0;
   static int nzap=0;
-  static int n60z=0;
+  static int ntrz=0;
   static int nkhz;
   static int nfsample=96000;
   static int nxpol=0;
@@ -536,27 +540,34 @@ void MainWindow::dataSink(int k)
 
 // Time according to this computer
     qint64 ms = QDateTime::currentMSecsSinceEpoch() % 86400000;
-    int n60 = (ms/1000) % 60;
-    if((m_diskData && ihsym <= m_waterfallAvg) || (!m_diskData && n60<n60z)) {
+    int ntr = (ms/1000) % m_TRperiod;
+    if((m_diskData && ihsym <= m_waterfallAvg) || (!m_diskData && ntr<ntrz)) {
       for (int i=0; i<NFFT; i++) {
         splot[i] = 1.e30;
       }
     }
-    n60z=n60;
+    ntrz=ntr;
     n=0;
   }
-  if(ihsym == 279) {
+  if(ihsym == 279/m_nfast) {
     datcom_.newdat=1;
     datcom_.nagain=0;
     QDateTime t = QDateTime::currentDateTimeUtc();
     m_dateTime=t.toString("yyyy-MMM-dd hh:mm");
     decode();                                           //Start the decoder
-    if(m_saveAll) {
+    if(m_saveAll and !m_diskData) {
       QString fname=m_saveDir + "/" + t.date().toString("yyMMdd") + "_" +
           t.time().toString("hhmm");
+      if(m_nfast==2) {
+        if(t.time().second() < 30) {
+          fname += "00";
+        } else {
+          fname += "30";
+        }
+      }
       if(m_xpol) fname += ".tf2";
       if(!m_xpol) fname += ".iq";
-      *future2 = QtConcurrent::run(savetf2, fname, m_xpol);
+      *future2 = QtConcurrent::run(savetf2, fname, m_xpol, m_nfast);
       watcher2->setFuture(*future2);
     }
   }
@@ -970,7 +981,7 @@ void MainWindow::on_actionOpen_triggered()                     //Open File
     m_diskData=true;
     int dbDgrd=0;
     if(m_myCall=="K1JT" and m_idInt<0) dbDgrd=m_idInt;
-    *future1 = QtConcurrent::run(getfile, fname, m_xpol, dbDgrd);
+    *future1 = QtConcurrent::run(getfile, fname, m_xpol, dbDgrd, m_nfast);
     watcher1->setFuture(*future1);
   }
 }
@@ -1005,7 +1016,7 @@ void MainWindow::on_actionOpen_next_in_directory_triggered()   //Open Next
       m_diskData=true;
       int dbDgrd=0;
       if(m_myCall=="K1JT" and m_idInt<0) dbDgrd=m_idInt;
-      *future1 = QtConcurrent::run(getfile, fname, m_xpol, dbDgrd);
+      *future1 = QtConcurrent::run(getfile, fname, m_xpol, dbDgrd, m_nfast);
       watcher1->setFuture(*future1);
       return;
     }
@@ -1027,14 +1038,14 @@ void MainWindow::diskDat()                                   //diskDat()
 
   if(m_fs96000) hsym=2048.0*96000.0/11025.0;   //Samples per JT65 half-symbol
   if(!m_fs96000) hsym=2048.0*95238.1/11025.0;
-  for(int i=0; i<281; i++) {              // Do the half-symbol FFTs
+  for(int i=0; i<282/m_nfast; i++) {           // Do the half-symbol FFTs
     int k = i*hsym + 2048.5;
     dataSink(k);
-    if(i%10 == 0) qApp->processEvents();   //Keep the GUI responsive
+    if(i%10 == 0) qApp->processEvents();       //Keep the GUI responsive
   }
 }
 
-void MainWindow::diskWriteFinished()                       //diskWriteFinished
+void MainWindow::diskWriteFinished()                      //diskWriteFinished
 {
 //  qDebug() << "diskWriteFinished";
 }
@@ -1133,8 +1144,11 @@ void MainWindow::on_actionAvailable_suffixes_and_add_on_prefixes_triggered()
 
 void MainWindow::on_DecodeButton_clicked()                    //Decode request
 {
-  int n=m_sec0%60;
-  if(m_monitoring and n>47 and (n<52 or m_decoderBusy)) return;
+  int n=m_sec0%m_TRperiod;
+  if(m_nfast==1) {
+    if(m_monitoring and n>47 and (n<52 or m_decoderBusy)) return;
+  } else {
+    if(m_monitoring and n>21 and (n<26 or m_decoderBusy)) return;  }
   if(!m_decoderBusy) {
     datcom_.newdat=0;
     datcom_.nagain=1;
@@ -1343,8 +1357,8 @@ void MainWindow::guiUpdate()
   double tx2=126.0*4096.0/11025.0 + 1.8;          //### depend on TxDelay? ###
 
   if(!m_txFirst) {
-    tx1 += 60.0;
-    tx2 += 60.0;
+    tx1 += m_TRperiod;
+    tx2 += m_TRperiod;
   }
   qint64 ms = QDateTime::currentMSecsSinceEpoch() % 86400000;
   int nsec=ms/1000;
@@ -1900,7 +1914,7 @@ void MainWindow::on_logQSOButton_clicked()                 //Log QSO button
   QDateTime t = QDateTime::currentDateTimeUtc();
   QString logEntry=t.date().toString("yyyy-MMM-dd,") +
       t.time().toString("hh:mm,") + m_hisCall + "," + m_hisGrid + "," +
-      QString::number(nMHz) + ",JT65B\n";
+      QString::number(nMHz) + "," + m_mode;
   QFile f("wsjt.log");
   if(!f.open(QFile::Append)) {
     msgBox("Cannot open file \"wsjt.log\".");
@@ -1937,6 +1951,9 @@ void MainWindow::on_actionJT65A_triggered()
 {
   m_mode="JT65A";
   m_mode65=1;
+  m_nfast=1;
+  m_TRperiod=60;
+  soundInThread.setPeriod(m_TRperiod);
   g_pWideGraph->setMode65(m_mode65);
   lab5->setText(m_mode);
   ui->actionJT65A->setChecked(true);
@@ -1946,6 +1963,9 @@ void MainWindow::on_actionJT65B_triggered()
 {
   m_mode="JT65B";
   m_mode65=2;
+  m_nfast=1;
+  m_TRperiod=60;
+  soundInThread.setPeriod(m_TRperiod);
   g_pWideGraph->setMode65(m_mode65);
   lab5->setText(m_mode);
   ui->actionJT65B->setChecked(true);
@@ -1955,11 +1975,38 @@ void MainWindow::on_actionJT65C_triggered()
 {
   m_mode="JT65C";
   m_mode65=4;
+  m_nfast=1;
+  m_TRperiod=60;
+  soundInThread.setPeriod(m_TRperiod);
   g_pWideGraph->setMode65(m_mode65);
   lab5->setText(m_mode);
   ui->actionJT65C->setChecked(true);
 }
 
+void MainWindow::on_actionJT65B2_triggered()
+{
+  m_mode="JT65B2";
+  m_mode65=2;
+  m_nfast=2;
+  m_TRperiod=30;
+  soundInThread.setPeriod(m_TRperiod);
+  g_pWideGraph->setMode65(m_mode65);
+  lab5->setText(m_mode);
+  ui->actionJT65B2->setChecked(true);
+}
+
+void MainWindow::on_actionJT65C2_triggered()
+{
+  m_mode="JT65C2";
+  m_mode65=4;
+  m_nfast=2;
+  m_TRperiod=30;
+  soundInThread.setPeriod(m_TRperiod);
+  g_pWideGraph->setMode65(m_mode65);
+  lab5->setText(m_mode);
+  ui->actionJT65C2->setChecked(true);
+}
+
 void MainWindow::on_NBcheckBox_toggled(bool checked)
 {
   m_NB=checked;
diff --git a/mainwindow.h b/mainwindow.h
index 45b6dab86..d5b8f7ea5 100644
--- a/mainwindow.h
+++ b/mainwindow.h
@@ -5,6 +5,7 @@
 #include <QTimer>
 #include <QDateTime>
 #include <QHash>
+#include "getfile.h"
 #include "soundin.h"
 #include "soundout.h"
 #include "commons.h"
@@ -123,6 +124,10 @@ private slots:
 
   void on_actionFUNcube_Dongle_triggered();
 
+  void on_actionJT65B2_triggered();
+
+  void on_actionJT65C2_triggered();
+
 private:
     Ui::MainWindow *ui;
     qint32  m_nDevIn;
@@ -157,6 +162,7 @@ private:
     qint32  m_nfast;
     qint32  m_nsum;
     qint32  m_nsave;
+    qint32  m_TRperiod;
 
     double  m_fAdd;
     double  m_IQamp;
diff --git a/mainwindow.ui b/mainwindow.ui
index 0a3b6c481..d826e2181 100644
--- a/mainwindow.ui
+++ b/mainwindow.ui
@@ -1225,6 +1225,8 @@ p, li { white-space: pre-wrap; }
     <addaction name="actionJT65A"/>
     <addaction name="actionJT65B"/>
     <addaction name="actionJT65C"/>
+    <addaction name="actionJT65B2"/>
+    <addaction name="actionJT65C2"/>
    </widget>
    <addaction name="menuFile"/>
    <addaction name="menuSetup"/>
@@ -1568,6 +1570,22 @@ p, li { white-space: pre-wrap; }
     <string>FUNcube Dongle Settings</string>
    </property>
   </action>
+  <action name="actionJT65B2">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>JT65B2</string>
+   </property>
+  </action>
+  <action name="actionJT65C2">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>JT65C2</string>
+   </property>
+  </action>
  </widget>
  <layoutdefault spacing="6" margin="11"/>
  <customwidgets>
diff --git a/soundin.cpp b/soundin.cpp
index a6091729a..a7b3cfe96 100644
--- a/soundin.cpp
+++ b/soundin.cpp
@@ -187,10 +187,10 @@ void SoundInThread::run()                           //SoundInThread::run()
 //  const PaStreamInfo* p=Pa_GetStreamInfo(inStream);
 
   bool qe = quitExecution;
-  int n60z=99;
+  int ntrz=99;
   int k=0;
   int nsec;
-  int n60;
+  int ntr;
   int nBusy=0;
   int nhsym0=0;
 
@@ -200,10 +200,10 @@ void SoundInThread::run()                           //SoundInThread::run()
     if (qe) break;
     qint64 ms = QDateTime::currentMSecsSinceEpoch() % 86400000;
     nsec = ms/1000;             // Time according to this computer
-    n60 = nsec % 60;
+    ntr = nsec % m_TRperiod;
 
 // Reset buffer pointer and symbol number at start of minute
-    if(n60 < n60z or !m_monitoring) {
+    if(ntr < ntrz or !m_monitoring) {
       nhsym0=0;
       udata.bzero=true;
     }
@@ -228,7 +228,7 @@ void SoundInThread::run()                           //SoundInThread::run()
       }
     }
     msleep(100);
-    n60z=n60;
+    ntrz=ntr;
   }
   Pa_StopStream(inStream);
   Pa_CloseStream(inStream);
@@ -314,6 +314,11 @@ int SoundInThread::mhsym()
   return m_hsym;
 }
 
+void SoundInThread::setPeriod(int n)
+{
+  m_TRperiod=n;
+}
+
 //--------------------------------------------------------------- inputUDP()
 void SoundInThread::inputUDP()
 {
@@ -341,10 +346,10 @@ void SoundInThread::inputUDP()
     double d8[174];
   } b;
 
-  int n60z=99;
+  int ntrz=99;
   int k=0;
   int nsec;
-  int n60;
+  int ntr;
   int nhsym0=0;
   int iz=174;
   int nBusy=0;
@@ -361,14 +366,14 @@ void SoundInThread::inputUDP()
 
       qint64 ms = QDateTime::currentMSecsSinceEpoch() % 86400000;
       nsec = ms/1000;             // Time according to this computer
-      n60 = nsec % 60;
+      ntr = nsec % m_TRperiod;
 
 // Reset buffer pointer and symbol number at start of minute
-      if(n60 < n60z) {
+      if(ntr < ntrz) {
         k=0;
         nhsym0=0;
       }
-      n60z=n60;
+      ntrz=ntr;
 
       if(m_monitoring) {
         m_nrx=b.nrx;
diff --git a/soundin.h b/soundin.h
index db8d71016..30862b568 100644
--- a/soundin.h
+++ b/soundin.h
@@ -47,6 +47,7 @@ public:
   void setNrx(int n);
   void setForceCenterFreqBool(bool b);
   void setForceCenterFreqMHz(double d);
+  void setPeriod(int n);
   int  nrx();
   int  mhsym();
 
@@ -73,6 +74,7 @@ private:
   qint32 m_hsym;
   qint32 m_nDevIn;
   qint32 m_udpPort;
+  qint32 m_TRperiod;
 
   QUdpSocket *udpSocket;
 };
diff --git a/soundout.cpp b/soundout.cpp
index 3ee67bddc..f0101ce2f 100644
--- a/soundout.cpp
+++ b/soundout.cpp
@@ -15,7 +15,7 @@ extern double outputLatency;
 
 typedef struct   //Parameters sent to or received from callback function
 {
-  int dummy;
+  int nTRperiod;
 } paUserData;
 
 //--------------------------------------------------------------- d2aCallback
@@ -29,14 +29,11 @@ extern "C" int d2aCallback(const void *inputBuffer, void *outputBuffer,
   short *wptr = (short*)outputBuffer;
   unsigned int i,n;
   static int ic=0;
-//  static int ic0=0;
-//  static int nsec0=-99;
   static bool btxok0=false;
   static int nminStart=0;
-//  static t0,t1;
   double tsec,tstart;
-
   int nsec;
+  int nTRperiod=udata->nTRperiod;
 
   // Get System time
   qint64 ms = QDateTime::currentMSecsSinceEpoch() % 86400000;
@@ -44,46 +41,21 @@ extern "C" int d2aCallback(const void *inputBuffer, void *outputBuffer,
   nsec = ms/1000;
 
   if(btxok and !btxok0) {       //Start (or re-start) a transmission
-    n=nsec/60;
-    tstart=tsec - n*60.0 - 1.0;
+    n=nsec/nTRperiod;
+    tstart=tsec - n*nTRperiod - 1.0;
 
     if(tstart<1.0) {
       ic=0;                      //Start of minute, set starting index to 0
-//      ic0=ic;
       nminStart=n;
-//      t0=timeInfo->currentTime;
     } else {
       if(n != nminStart) { //Late start in new minute: compute starting index
         ic=(int)(tstart*11025.0);
-//        ic0=ic;
-//        t0=timeInfo->currentTime;
-//        qDebug() << "B" << t0 << ic0;
         nminStart=n;
       }
     }
-    /*
-    qDebug() << "A" << n << ic
-             << QString::number( tsec, 'f', 3 )
-             << QString::number( tstart, 'f', 3 )
-             << QString::number( timeInfo->currentTime, 'f', 3 )
-             << QString::number( timeInfo->outputBufferDacTime, 'f', 3 )
-             << QString::number( timeInfo->outputBufferDacTime -
-                                 timeInfo->currentTime, 'f', 3 )
-             << QString::number( timeInfo->currentTime - tsec, 'f', 3 );
-    */
   }
   btxok0=btxok;
 
-  /*
-  if(nsec!=nsec0) {
-    double txt=timeInfo->currentTime - t0;
-    double r=0.0;
-    if(txt>0.0) r=(ic-ic0)/txt;
-    qDebug() << "C" << txt << ic-ic0 << r;
-    nsec0=nsec;
-  }
-  */
-
   if(btxok) {
     for(i=0 ; i<framesToProcess; i++ )  {
       short int i2=iwave[ic];
@@ -122,6 +94,8 @@ void SoundOutThread::run()
   outParam.suggestedLatency=0.05;
   outParam.hostApiSpecificStreamInfo=NULL;
 
+  udata.nTRperiod=m_TRperiod;
+
   paerr=Pa_IsFormatSupported(NULL,&outParam,11025.0);
   if(paerr<0) {
     qDebug() << "PortAudio says requested output format not supported.";
@@ -129,9 +103,6 @@ void SoundOutThread::run()
     return;
   }
 
-//  udata.nwave=m_nwave;
-//  udata.btxok=false;
-
   paerr=Pa_OpenStream(&outStream,           //Output stream
         NULL,                               //No input parameters
         &outParam,                          //Output parameters
@@ -154,9 +125,6 @@ void SoundOutThread::run()
   while (!qe) {
     qe = quitExecution;
     if (qe) break;
-//    udata.nwave=m_nwave;
-//    if(m_txOK) udata.btxok=1;
-//    if(!m_txOK) udata.btxok=0;
     msleep(100);
   }
   Pa_StopStream(outStream);
@@ -168,3 +136,8 @@ void SoundOutThread::setOutputDevice(int n)      //setOutputDevice()
   if (isRunning()) return;
   this->m_nDevOut=n;
 }
+
+void SoundOutThread::setPeriod(int n)
+{
+  m_TRperiod=n;
+}
diff --git a/soundout.h b/soundout.h
index 198c6d763..294c6fa5f 100644
--- a/soundout.h
+++ b/soundout.h
@@ -27,6 +27,7 @@ public:
 
 public:
   void setOutputDevice(qint32 n);
+  void setPeriod(int n);
   bool quitExecution;           //If true, thread exits gracefully
 
 
@@ -35,6 +36,7 @@ private:
   double  m_rate;               //Sample rate
   qint32  m_nDevOut;            //Output device number
   qint32  m_nwave;              //Length of wave file
+  qint32  m_TRperiod;           //T/R period (30 or 60 s)
   bool    m_txOK;               //Enable Tx audio
   bool    m_txMute;             //Mute temporarily
 };