diff --git a/Modem/config.h b/Modem/config.h
index d3e171a..2bdc2ca 100644
--- a/Modem/config.h
+++ b/Modem/config.h
@@ -19,7 +19,7 @@
 #define CONFIG_AFSK_RXTIMEOUT 0				// How long a read operation from the modem
 											// will wait for data before timing out.
 
-#define CONFIG_AFSK_PREAMBLE_LEN 150UL		// The length of the packet preamble in milliseconds
-#define CONFIG_AFSK_TRAILER_LEN 50UL		// The length of the packet tail in milliseconds
+#define CONFIG_AFSK_PREAMBLE_LEN 550UL		// The length of the packet preamble in milliseconds
+#define CONFIG_AFSK_TRAILER_LEN 10UL		// The length of the packet tail in milliseconds
 
 #endif
\ No newline at end of file
diff --git a/Modem/protocol/mp1.h b/Modem/protocol/mp1.h
index f5fae32..a3e04d6 100644
--- a/Modem/protocol/mp1.h
+++ b/Modem/protocol/mp1.h
@@ -24,9 +24,9 @@
 
 // These two parameters are used for 
 // P-persistent CSMA
-#define MP1_SETTLE_TIME 100UL		// The minimum wait time before considering sending
-#define MP1_P_PERSISTENCE 85UL		// The probability (between 0 and 255) for sending
-#define MP1_TXDELAY 150UL			// Delay between turning on the transmitter and sending
+#define MP1_SETTLE_TIME 250UL		// The minimum wait time before considering sending
+#define MP1_P_PERSISTENCE 64UL		// The probability (between 0 and 255) for sending
+#define MP1_TXDELAY 0UL				// Delay between turning on the transmitter and sending
 
 // We need to know some basic HDLC flag bytes
 #define HDLC_FLAG  0x7E
diff --git a/buildrev.h b/buildrev.h
index b3dc872..8c410c3 100644
--- a/buildrev.h
+++ b/buildrev.h
@@ -1,2 +1,2 @@
-#define VERS_BUILD 1599
+#define VERS_BUILD 1603
 #define VERS_HOST  "shard"