Fixes #42

src/NmeaParser/Nmea/Gps/GPVTG.cs

@@ -0,0 +1,64 @@
+//
+// Copyright (c) 2014 Morten Nielsen
+//
+// Licensed under the Microsoft Public License (Ms-PL) (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://opensource.org/licenses/Ms-PL.html
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace NmeaParser.Nmea.Gps
+{
+    /// <summary>
+	///  Course over ground and ground speed
+	/// </summary>
+	[System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA1704:IdentifiersShouldBeSpelledCorrectly", MessageId = "GPVTG")]
+    [NmeaMessageType("GPVTG")]
+    public class Gpvtg : NmeaMessage
+    {
+        /// <summary>
+        /// Called when the message is being loaded.
+        /// </summary>
+        /// <param name="message">The NMEA message values.</param>
+        protected override void OnLoadMessage(string[] message)
+        {
+            if (message == null || message.Length < 7)
+                throw new ArgumentException("Invalid Gpvtg", "message");
+            TrueCourseOverGround = NmeaMessage.StringToDouble(message[0]);
+            MagneticCourseOverGround = NmeaMessage.StringToDouble(message[2]);
+            SpeedInKnots = NmeaMessage.StringToDouble(message[4]);
+            SpeedInKph = NmeaMessage.StringToDouble(message[6]);
+        }
+
+        /// <summary>
+        ///  Course over ground relative to true north
+        /// </summary>
+        public double TrueCourseOverGround { get; private set; } = double.NaN;
+
+        /// <summary>
+        ///  Course over ground relative to magnetic north
+        /// </summary>
+        public double MagneticCourseOverGround { get; private set; } = double.NaN;
+
+        /// <summary>
+        /// Speed over ground in knots
+        /// </summary>
+        public double SpeedInKnots { get; private set; } = double.NaN;
+
+        /// <summary>
+        /// Speed over ground in kilometers/hour
+        /// </summary>
+        public double SpeedInKph { get; private set; } = double.NaN;
+    }
+}

src/UnitTests/NmeaParser.Tests/NmeaMessages.cs

@@ -588,5 +588,31 @@ namespace NmeaParser.Tests
             Assert.AreEqual(0.020, gst.SigmaLongitudeError);
             Assert.AreEqual(0.031, gst.SigmaHeightError);
         }
+
+        [TestMethod]
+        public void TestGpvtg()
+        {
+            string input = "$GPVTG,103.85,T,92.79,M,0.14,N,0.25,K,D*1E";
+            var msg = NmeaMessage.Parse(input);
+            Assert.IsInstanceOfType(msg, typeof(Gpvtg));
+            Gpvtg vtg = (Gpvtg)msg;
+            Assert.AreEqual(103.85, vtg.TrueCourseOverGround);
+            Assert.AreEqual(92.79, vtg.MagneticCourseOverGround);
+            Assert.AreEqual(0.14, vtg.SpeedInKnots);
+            Assert.AreEqual(0.25, vtg.SpeedInKph);
+        }
+
+        [TestMethod]
+        public void TestGpvtg_Empty()
+        {
+            string input = "$GPVTG,,T,,M,0.00,N,0.00,K*4E";
+            var msg = NmeaMessage.Parse(input);
+            Assert.IsInstanceOfType(msg, typeof(Gpvtg));
+            Gpvtg vtg = (Gpvtg)msg;
+            Assert.IsTrue(double.IsNaN(vtg.TrueCourseOverGround));
+            Assert.IsTrue(double.IsNaN(vtg.MagneticCourseOverGround));
+            Assert.AreEqual(0.0, vtg.SpeedInKnots);
+            Assert.AreEqual(0.0, vtg.SpeedInKph);
+        }
     }
 }