diff --git a/commons.h b/commons.h
index 17fc89d..348852c 100644
--- a/commons.h
+++ b/commons.h
@@ -35,7 +35,7 @@
 #define JS8E_TX_SECONDS     4
 #define JS8E_START_DELAY_MS 100
 #else
-#define JS8E_SYMBOL_SAMPLES 4000
+#define JS8E_SYMBOL_SAMPLES 3840
 #define JS8E_TX_SECONDS     30
 #define JS8E_START_DELAY_MS 500
 #endif
diff --git a/lib/js8/js8e_params.f90 b/lib/js8/js8e_params.f90
index b4a30fe..e0e0632 100644
--- a/lib/js8/js8e_params.f90
+++ b/lib/js8/js8e_params.f90
@@ -17,7 +17,8 @@
 ! parameter (NSPS=960,  NTXDUR=8,  NDOWNSPS=24, NDD=100, JZ=116) ! 100 Hz  12.50 baud 32 wpm -22.0dB (1.0Eb/N0)  5.92s
 ! parameter (NSPS=1200, NTXDUR=10, NDOWNSPS=20, NDD=100, JZ=116) !  80 Hz     10 baud 24 wpm -23.0dB (1.0Eb/N0)  7.90s
 ! parameter (NSPS=1920, NTXDUR=15, NDOWNSPS=32, NDD=100, JZ=116) !  50 Hz  6.250 baud 16 wpm -25.0dB (1.0Eb/N0) 12.64s
-  parameter (NSPS=4000, NTXDUR=30, NDOWNSPS=40, NDD=90,  JZ=116) !  24 Hz      3 baud  8 wpm -28.2dB (1.0Eb/N0) 26.33s
+  parameter (NSPS=3840, NTXDUR=30, NDOWNSPS=32, NDD=94,  JZ=116) !  24 Hz  3.125 baud  8 wpm -28.0dB (1.0Eb/N0) 25.28s
+! parameter (NSPS=4000, NTXDUR=30, NDOWNSPS=40, NDD=90,  JZ=116) !  24 Hz      3 baud  8 wpm -28.2dB (1.0Eb/N0) 26.33s
 
 parameter (AZ=12000.0/(1.0*NSPS)*0.8d0) !Dedupe overlap in Hz
 parameter (ASTART=0.5)                   !Start delay in seconds
diff --git a/mainwindow.cpp b/mainwindow.cpp
index 50ae4b8..f247609 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -1031,7 +1031,7 @@ MainWindow::MainWindow(QDir const& temp_directory, bool multiple,
       // reorder so slow is at the top
       ui->menuModeJS8->removeAction(ui->actionModeJS8UltraSlow);
       ui->menuModeJS8->insertAction(ui->actionModeJS8Normal, ui->actionModeJS8UltraSlow);
-      ui->actionModeJS8UltraSlow->setText("JS8 (&Slow, 30s, 24Hz, ~8WPM)");
+      ui->actionModeJS8UltraSlow->setText("JS8 (&Slow, 30s, 25Hz, ~8WPM)");
   }
 
   // prep
@@ -2491,9 +2491,9 @@ void MainWindow::fixStop()
 
 int MainWindow::computeSubmodePeriod(int submode){
     switch(submode){
-        case Varicode::JS8CallNormal: return JS8A_TX_SECONDS;
-        case Varicode::JS8CallFast:   return JS8B_TX_SECONDS;
-        case Varicode::JS8CallTurbo:  return JS8C_TX_SECONDS;
+        case Varicode::JS8CallNormal:     return JS8A_TX_SECONDS;
+        case Varicode::JS8CallFast:       return JS8B_TX_SECONDS;
+        case Varicode::JS8CallTurbo:      return JS8C_TX_SECONDS;
         case Varicode::JS8CallUltraSlow:  return JS8E_TX_SECONDS;
     }
 
@@ -4003,16 +4003,15 @@ bool MainWindow::decodeReady(int submode, int period, int *pSubmode, int *pPerio
     qint32 cycleSampleStartE = computeCycleStartForDecode(cycleE, JS8E_TX_SECONDS);
     qint32 framesNeededE = computeFramesNeededForDecode(Varicode::JS8CallUltraSlow, JS8E_TX_SECONDS);
     bool couldDecodeE = k >= cycleSampleStartE + framesNeededE;
-#if !JS8E_IS_ULTRA
-    static int lastE = -1;
+
+    // protect against multiple decodes for the same cycle
+    static int lastDecodeCycleE = -1;
     if(couldDecodeE){
-        if(cycleE == lastE){
+        if(cycleE == lastDecodeCycleE){
             couldDecodeE = false;
         }
-        lastE = cycleE;
+        lastDecodeCycleE = cycleE;
     }
-#endif
-
 #else
     qint32 cycleSampleStartE = 0;
     qint32 framesNeededE = 0;
@@ -4504,7 +4503,7 @@ void MainWindow::readFromStdout()                             //readFromStdout
       DecodedText decodedtext {QString::fromUtf8 (t.constData ()).remove (QRegularExpression {"\r|\n"}), "FT8" == m_mode &&
             ui->cbVHFcontest->isChecked(), m_config.my_grid ()};
 
-      bool bValidFrame = decodedtext.snr() > -24;
+      bool bValidFrame = decodedtext.snr() > -28;
 
       // dupe check
       auto frame = decodedtext.message();
@@ -7220,7 +7219,7 @@ void MainWindow::prepareHeartbeatMode(bool enabled){
         ui->hbMacroButton->setChecked(false);
     }
     ui->actionHeartbeat->setEnabled(enabled);
-    ui->actionModeJS8HB->setEnabled(m_nSubMode == Varicode::JS8CallNormal);
+    ui->actionModeJS8HB->setEnabled(m_nSubMode == Varicode::JS8CallNormal || (!JS8E_IS_ULTRA && m_nSubMode == Varicode::JS8CallUltraSlow));
     ui->actionHeartbeatAcknowledgements->setEnabled(ui->actionModeAutoreply->isChecked() && enabled);
 
 #if 0
@@ -7268,7 +7267,7 @@ void MainWindow::on_actionJS8_triggered()
   }
 
   // Only enable heartbeat for normal mode
-  ui->actionModeJS8HB->setEnabled(m_nSubMode == Varicode::JS8CallNormal);
+  ui->actionModeJS8HB->setEnabled(m_nSubMode == Varicode::JS8CallNormal || (!JS8E_IS_ULTRA && m_nSubMode == Varicode::JS8CallUltraSlow));
   prepareHeartbeatMode(ui->actionModeJS8HB->isEnabled() && ui->actionModeJS8HB->isChecked());
 
   //if(m_nSubMode != Varicode::JS8CallNormal){
diff --git a/varicode.h b/varicode.h
index 4d6f4ee..6e8c71b 100644
--- a/varicode.h
+++ b/varicode.h
@@ -25,11 +25,10 @@ public:
 
     // submode types
     enum SubmodeType {
-        JS8CallNormal   = 0,
-        JS8CallFast     = 1,
-        JS8CallTurbo    = 2,
-        JS8CallSlow     = 4,
-        JS8CallUltraSlow    = 4
+        JS8CallNormal    = 0,
+        JS8CallFast      = 1,
+        JS8CallTurbo     = 2,
+        JS8CallUltraSlow = 4
     };
 
     // frame type transmitted via itype and decoded by the ft8 decoded