diff --git a/DMRDMOTX.cpp b/DMRDMOTX.cpp
index deb4ff8..f491f13 100644
--- a/DMRDMOTX.cpp
+++ b/DMRDMOTX.cpp
@@ -21,6 +21,13 @@
 #include "Config.h"
 #include "Globals.h"
 
+// PR FILL pattern
+const uint8_t PR_FILL[] =
+        {0x63U, 0xEAU, 0x00U, 0x76U, 0x6CU, 0x76U, 0xC4U, 0x52U, 0xC8U, 0x78U,
+         0x09U, 0x2DU, 0xB8U, 0x79U, 0x27U, 0x57U, 0x9BU, 0x31U, 0xBCU, 0x3EU,
+         0xEAU, 0x45U, 0xC3U, 0x30U, 0x49U, 0x17U, 0x93U, 0xAEU, 0x8BU, 0x6DU,
+         0xA4U, 0xA5U, 0xADU, 0xA2U, 0xF1U, 0x35U, 0xB5U, 0x3CU, 0x1EU};
+
 const uint8_t DMR_SYNC = 0x5FU;
 
 CDMRDMOTX::CDMRDMOTX() :
@@ -51,13 +58,15 @@ void CDMRDMOTX::process()
       } else {
         m_delay = false;
 
-        for (unsigned int i = 0U; i < 72U; i++)
-          m_poBuffer[m_poLen++] = DMR_SYNC;
-
         for (unsigned int i = 0U; i < DMR_FRAME_LENGTH_BYTES; i++)
           m_poBuffer[i] = m_fifo.get();
+
+        for (unsigned int i = 0U; i < 39U; i++)
+          m_poBuffer[i + DMR_FRAME_LENGTH_BYTES] = PR_FILL[i];
+
       }
       m_poPtr = 0U;
+      m_poLen = 72U;
     }
   }