diff --git a/Config.h b/Config.h
index 603b0a1..04f3f4b 100644
--- a/Config.h
+++ b/Config.h
@@ -19,6 +19,8 @@
 #if !defined(CONFIG_H)
 #define  CONFIG_H
 
+#define USE_SHORTER_DMR_FILTER
+
 // Allow for the use of high quality external clock oscillators
 // The number is the frequency of the oscillator in Hertz.
 // For 12 MHz
diff --git a/DMRTX.cpp b/DMRTX.cpp
index 73d8c3c..6228879 100644
--- a/DMRTX.cpp
+++ b/DMRTX.cpp
@@ -20,17 +20,24 @@
 #include "Globals.h"
 #include "DMRSlotType.h"
 
+#if defined(USE_SHORTER_DMR_FILTER)
+// Generated using rcosdesign(0.2, 4, 10, 'sqrt') in MATLAB
+static q15_t   DMR_C4FSK_FILTER[] = {486, 39, -480, -1022, -1526, -1928, -2164, -2178, -1927, -1384, -548, 561, 1898, 3399, 4980, 6546, 7999, 9246, 10202, 10803, 11008, 10803, 10202, 9246,
+                                     7999, 6546, 4980, 3399, 1898, 561, -548, -1384, -1927, -2178, -2164, -1928, -1526, -1022, -480, 39, 486, 0};
+const uint16_t DMR_C4FSK_FILTER_LEN = 42U;
+#else
 // Generated using rcosdesign(0.2, 8, 10, 'sqrt') in MATLAB
 static q15_t   DMR_C4FSK_FILTER[] = {283, 198, 73, -78, -240, -393, -517, -590, -599, -533, -391, -181, 79, 364, 643, 880, 1041, 1097, 1026, 819, 483, 39, -477, -1016, -1516, -1915, -2150,
                                      -2163, -1914, -1375, -545, 557, 1886, 3376, 4946, 6502, 7946, 9184, 10134, 10731, 10935, 10731, 10134, 9184, 7946, 6502, 4946, 3376, 1886, 557, -545,
                                      -1375, -1914, -2163, -2150, -1915, -1516, -1016, -477, 39, 483, 819, 1026, 1097, 1041, 880, 643, 364, 79, -181, -391, -533, -599, -590, -517, -393, -240,
                                      -78, 73, 198, 283, 0};
 const uint16_t DMR_C4FSK_FILTER_LEN = 82U;
+#endif
 
-q15_t DMR_A[] = { 1280,  1280,  1280,  1280,  1280};
-q15_t DMR_B[] = {  427,   427,   427,   427,   427};
-q15_t DMR_C[] = { -427,  -427,  -427,  -427,  -427};
-q15_t DMR_D[] = {-1280, -1280, -1280, -1280, -1280};
+q15_t DMR_A[] = { 1280,  1280,  1280,  1280,  1280,  1280,  1280,  1280,  1280,  1280};
+q15_t DMR_B[] = {  427,   427,   427,   427,   427,   427,   427,   427,   427,   427};
+q15_t DMR_C[] = { -427,  -427,  -427,  -427,  -427,  -427,  -427,  -427,  -427,  -427};
+q15_t DMR_D[] = {-1280, -1280, -1280, -1280, -1280, -1280, -1280, -1280, -1280, -1280};
 
 // The PR FILL and Data Sync pattern.
 const uint8_t IDLE_DATA[] =
diff --git a/DStarTX.cpp b/DStarTX.cpp
index cc4d866..a357cac 100644
--- a/DStarTX.cpp
+++ b/DStarTX.cpp
@@ -30,8 +30,8 @@ const uint8_t FRAME_SYNC[] = {0xEAU, 0xA6U, 0x00U};
 static q15_t   DSTAR_GMSK_FILTER[] = {1, 4, 15, 52, 151, 380, 832, 1579, 2599, 3710, 4594, 4933, 4594, 3710, 2599, 1579, 832, 380, 151, 52, 15, 4, 1, 0};
 const uint16_t DSTAR_GMSK_FILTER_LEN = 24U;
 
-q15_t DSTAR_1[] = { 1600,  1600,  1600,  1600,  1600};
-q15_t DSTAR_0[] = {-1600, -1600, -1600, -1600, -1600};
+q15_t DSTAR_1[] = { 1600,  1600,  1600,  1600,  1600,  1600,  1600,  1600,  1600,  1600};
+q15_t DSTAR_0[] = {-1600, -1600, -1600, -1600, -1600, -1600, -1600, -1600, -1600, -1600};
 
 const uint8_t BIT_MASK_TABLE[] = {0x80U, 0x40U, 0x20U, 0x10U, 0x08U, 0x04U, 0x02U, 0x01U};
 
diff --git a/IO.cpp b/IO.cpp
index 4343a9e..ee1fcf0 100644
--- a/IO.cpp
+++ b/IO.cpp
@@ -24,12 +24,19 @@
 #include "Globals.h"
 #include "IO.h"
 
+#if defined(USE_SHORTER_DMR_FILTER)
+// Generated using rcosdesign(0.2, 4, 10, 'sqrt') in MATLAB
+static q15_t   C4FSK_FILTER[] = {486, 39, -480, -1022, -1526, -1928, -2164, -2178, -1927, -1384, -548, 561, 1898, 3399, 4980, 6546, 7999, 9246, 10202, 10803, 11008, 10803, 10202, 9246,
+                                 7999, 6546, 4980, 3399, 1898, 561, -548, -1384, -1927, -2178, -2164, -1928, -1526, -1022, -480, 39, 486, 0};
+const uint16_t C4FSK_FILTER_LEN = 42U;
+#else
 // Generated using rcosdesign(0.2, 8, 10, 'sqrt') in MATLAB
 static q15_t   C4FSK_FILTER[] = {283, 198, 73, -78, -240, -393, -517, -590, -599, -533, -391, -181, 79, 364, 643, 880, 1041, 1097, 1026, 819, 483, 39, -477, -1016, -1516, -1915, -2150,
                                  -2163, -1914, -1375, -545, 557, 1886, 3376, 4946, 6502, 7946, 9184, 10134, 10731, 10935, 10731, 10134, 9184, 7946, 6502, 4946, 3376, 1886, 557, -545,
                                  -1375, -1914, -2163, -2150, -1915, -1516, -1016, -477, 39, 483, 819, 1026, 1097, 1041, 880, 643, 364, 79, -181, -391, -533, -599, -590, -517, -393, -240,
                                  -78, 73, 198, 283, 0};
 const uint16_t C4FSK_FILTER_LEN = 82U;
+#endif
 
 // Generated using gaussfir(0.5, 4, 10) in MATLAB
 static q15_t   GMSK_FILTER[] = {1, 4, 15, 52, 151, 380, 832, 1579, 2599, 3710, 4594, 4933, 4594, 3710, 2599, 1579, 832, 380, 151, 52, 15, 4, 1, 0};
diff --git a/YSFTX.cpp b/YSFTX.cpp
index e3a06cb..fd5f6ac 100644
--- a/YSFTX.cpp
+++ b/YSFTX.cpp
@@ -22,19 +22,27 @@
 
 #include "YSFDefines.h"
 
-// Generated using rcosdesign(0.2, 8, 5, 'sqrt') in MATLAB
-static q15_t YSF_C4FSK_FILTER[] = {401, 104, -340, -731, -847, -553, 112, 909, 1472, 1450, 683, -675, -2144, -3040, -2706, -770, 2667, 6995,
-                                   11237, 14331, 15464, 14331, 11237, 6995, 2667, -770, -2706, -3040, -2144, -675, 683, 1450, 1472, 909, 112,
-                                   -553, -847, -731, -340, 104, 401, 0};
+#if defined(USE_SHORTER_DMR_FILTER)
+// Generated using rcosdesign(0.2, 4, 10, 'sqrt') in MATLAB
+static q15_t   YSF_C4FSK_FILTER[] = {486, 39, -480, -1022, -1526, -1928, -2164, -2178, -1927, -1384, -548, 561, 1898, 3399, 4980, 6546, 7999, 9246, 10202, 10803, 11008, 10803, 10202, 9246,
+                                     7999, 6546, 4980, 3399, 1898, 561, -548, -1384, -1927, -2178, -2164, -1928, -1526, -1022, -480, 39, 486, 0};
 const uint16_t YSF_C4FSK_FILTER_LEN = 42U;
+#else
+// Generated using rcosdesign(0.2, 8, 10, 'sqrt') in MATLAB
+static q15_t   YSF_C4FSK_FILTER[] = {283, 198, 73, -78, -240, -393, -517, -590, -599, -533, -391, -181, 79, 364, 643, 880, 1041, 1097, 1026, 819, 483, 39, -477, -1016, -1516, -1915, -2150,
+                                     -2163, -1914, -1375, -545, 557, 1886, 3376, 4946, 6502, 7946, 9184, 10134, 10731, 10935, 10731, 10134, 9184, 7946, 6502, 4946, 3376, 1886, 557, -545,
+                                     -1375, -1914, -2163, -2150, -1915, -1516, -1016, -477, 39, 483, 819, 1026, 1097, 1041, 880, 643, 364, 79, -181, -391, -533, -599, -590, -517, -393, -240,
+                                     -78, 73, 198, 283, 0};
+const uint16_t YSF_C4FSK_FILTER_LEN = 82U;
+#endif
 
 const uint8_t YSF_START_SYNC = 0x77U;
 const uint8_t YSF_END_SYNC   = 0xFFU;
 
-q15_t YSF_A[] = { 1408,  1408,  1408,  1408,  1408};
-q15_t YSF_B[] = {  470,   470,   470,   470,   470};
-q15_t YSF_C[] = { -470,  -470,  -470,  -470,  -470};
-q15_t YSF_D[] = {-1408, -1408, -1408, -1408, -1408};
+q15_t YSF_A[] = { 1408,  1408,  1408,  1408,  1408,  1408,  1408,  1408,  1408,  1408};
+q15_t YSF_B[] = {  470,   470,   470,   470,   470,   470,   470,   470,   470,   470};
+q15_t YSF_C[] = { -470,  -470,  -470,  -470,  -470,  -470,  -470,  -470,  -470,  -470};
+q15_t YSF_D[] = {-1408, -1408, -1408, -1408, -1408, -1408, -1408, -1408, -1408, -1408};
 
 
 CYSFTX::CYSFTX() :
@@ -47,7 +55,7 @@ m_poPtr(0U),
 m_txDelay(120U),      // 100ms
 m_count(0U)
 {
-  ::memset(m_modState, 0x00U, 70U * sizeof(q15_t));
+  ::memset(m_modState, 0x00U, 130U * sizeof(q15_t));
 
   m_modFilter.numTaps = YSF_C4FSK_FILTER_LEN;
   m_modFilter.pState  = m_modState;
diff --git a/YSFTX.h b/YSFTX.h
index 9235a9c..421fbea 100644
--- a/YSFTX.h
+++ b/YSFTX.h
@@ -38,7 +38,7 @@ public:
 private:
   CSerialRB            m_buffer;
   arm_fir_instance_q15 m_modFilter;
-  q15_t                m_modState[70U];    // NoTaps + BlockSize - 1, 42 + 20 - 1 plus some spare
+  q15_t                m_modState[130U];    // NoTaps + BlockSize - 1, 82 + 40 - 1 plus some spare
   uint8_t              m_poBuffer[720U];
   uint16_t             m_poLen;
   uint16_t             m_poPtr;