Refactor NMEA checksum

3 files changed, 5 insertions, 4 deletions

diff --git a/src/main/java/org/traccar/protocol/GpsGateProtocolDecoder.java b/src/main/java/org/traccar/protocol/GpsGateProtocolDecoder.java
index cc187225b..c158d3212 100644
--- a/src/main/java/org/traccar/protocol/GpsGateProtocolDecoder.java
+++ b/src/main/java/org/traccar/protocol/GpsGateProtocolDecoder.java
@@ -69,7 +69,8 @@ public class GpsGateProtocolDecoder extends BaseProtocolDecoder {
 
     private void send(Channel channel, SocketAddress remoteAddress, String message) {
         if (channel != null) {
-            channel.writeAndFlush(new NetworkMessage(message + Checksum.nmea(message) + "\r\n", remoteAddress));
+            channel.writeAndFlush(new NetworkMessage(
+                    message + Checksum.nmea(message.substring(1)) + "\r\n", remoteAddress));
         }
     }
 
diff --git a/src/main/java/org/traccar/protocol/LaipacProtocolDecoder.java b/src/main/java/org/traccar/protocol/LaipacProtocolDecoder.java
index 0c72568f3..4abb75025 100644
--- a/src/main/java/org/traccar/protocol/LaipacProtocolDecoder.java
+++ b/src/main/java/org/traccar/protocol/LaipacProtocolDecoder.java
@@ -152,7 +152,7 @@ public class LaipacProtocolDecoder extends BaseProtocolDecoder {
 
         if (responseCode != null) {
             String response = "$AVCFG," + devicePassword + "," + responseCode;
-            response += Checksum.nmea(response) + "\r\n";
+            response += Checksum.nmea(response.substring(1)) + "\r\n";
             channel.writeAndFlush(new NetworkMessage(response, remoteAddress));
         }
 
@@ -163,7 +163,7 @@ public class LaipacProtocolDecoder extends BaseProtocolDecoder {
 
         if (Character.isLowerCase(status.charAt(0))) {
             String response = "$EAVACK," + event + "," + checksum;
-            response += Checksum.nmea(response) + "\r\n";
+            response += Checksum.nmea(response.substring(1)) + "\r\n";
             channel.writeAndFlush(new NetworkMessage(response, remoteAddress));
         }
 
diff --git a/src/main/java/org/traccar/protocol/LaipacProtocolEncoder.java b/src/main/java/org/traccar/protocol/LaipacProtocolEncoder.java
index 0c9f8ebb8..aaa5a70f7 100644
--- a/src/main/java/org/traccar/protocol/LaipacProtocolEncoder.java
+++ b/src/main/java/org/traccar/protocol/LaipacProtocolEncoder.java
@@ -29,7 +29,7 @@ public class LaipacProtocolEncoder extends StringProtocolEncoder {
     @Override
     protected String formatCommand(Command command, String format, String... keys) {
         String sentence = super.formatCommand(command, "$" + format, keys);
-        sentence += Checksum.nmea(sentence) + "\r\n";
+        sentence += Checksum.nmea(sentence.substring(1)) + "\r\n";
         return sentence;
     }