diff --git a/TBF/Rig/TestMethods/iPerlCommunication/iPerlHead/IperlHead.cs b/TBF/Rig/TestMethods/iPerlCommunication/iPerlHead/IperlHead.cs
index bdc90706a..1a1107d56 100644
--- a/TBF/Rig/TestMethods/iPerlCommunication/iPerlHead/IperlHead.cs
+++ b/TBF/Rig/TestMethods/iPerlCommunication/iPerlHead/IperlHead.cs
@@ -19,10 +19,14 @@ namespace TBF.Rig.TestMethods.iPerlCommunication.iPerlHead
         private static readonly ILog log = LogManager.GetLogger(typeof(IperlHead));
         public override string ToString() { return string.Format("{0}({1})", ClassName, Cfg.ToString(-1)); }
 
-
+#if TURA_SPECIAL
+        public const int MaxOptoDataCount = 250000;
+#else
         public const int MaxOptoDataCount = 40000;
+#endif
         public const int StartOptoDataCount = MaxOptoDataCount / 2;
         public const int EndOptoDataCount = MaxOptoDataCount - StartOptoDataCount;
+        public const int StartEndFilterSamplesCount2 = 20;      /// StartEndFilterSamplesCount = 2 * StartEndFilterSamplesCount2 + 1
         
         
 		readonly IperlHeadCfg iperlHeadCfg;
@@ -198,7 +202,7 @@ namespace TBF.Rig.TestMethods.iPerlCommunication.iPerlHead
 
 			if (meterVolume > 1E-2)
 			{
-				PositiveCounting = volumeLtrEnd > volumeLtrStart;
+				PositiveCounting = VolumeLtrEnd > VolumeLtrStart;
 
 				UInt16 newFactor = (UInt16)((double)originalCalibrationFactor * targetVolume / meterVolume + 0.5);
 				log.InfoFormat("Calibration factor: orig={0} new={1} V_iperl={2} V_ref={3} V_target={4}",
@@ -313,13 +317,10 @@ namespace TBF.Rig.TestMethods.iPerlCommunication.iPerlHead
         private double volumeLtr;
         private double volumeLtr0;
 
-        public double VolumeLtrStart { get { return volumeLtrStart; } }     /// Test start volume for metrology
-        public double VolumeLtrEnd { get { return volumeLtrEnd; } }         /// Test end volume for metrology
-        double volumeLtrStart;              /// Test start volume for metrology
-        double volumeLtrEnd;                /// Test end volume for metrology
-        double volumeLtrEnd1;               /// auxiliary buffer1 to keep the end volume before test stops
-		double volumeLtrEnd2;               /// auxiliary buffer2 to keep the end volume before test stops
-		double volumeLtrEnd3;               /// auxiliary buffer3 to keep the end volume before test stops
+        /// Test start volume for metrology in liters
+        public double VolumeLtrStart { get { return VolumeFromSamples(optoData, optoDataCount, TestStartTelegramIx, ScalingFactor(), StartEndFilterSamplesCount2); } }
+        /// Test end volume for metrology in liters
+        public double VolumeLtrEnd { get { return VolumeFromSamples(optoData, optoDataCount, TestEndTelegramIx, ScalingFactor(), StartEndFilterSamplesCount2); } }
 
 		///
         /// Timestamp from the opto telegram
@@ -328,23 +329,24 @@ namespace TBF.Rig.TestMethods.iPerlCommunication.iPerlHead
         private double timestampSec;
         private double timestampSec0;
 
-        public bool NoSamples { get { return (timestampSecEnd - timestampSecStart) < float.Epsilon; } }
-        public double TimestampSecStart { get { return timestampSecStart; } }
-        public double TimestampSecEnd { get { return timestampSecEnd; } }
-        double timestampSecStart;           
-        double timestampSecEnd;
-        double timestampSecEnd1;
-        double timestampSecEnd2;
-		double timestampSecEnd3;
+        public bool NoSamples { get { return (TimestampSecEnd - TimestampSecStart) < float.Epsilon; } }
 
+        /// Test start volume for metrology in seconds
+        public double TimestampSecStart { get { return TimeFromSamples(optoData, optoDataCount, TestStartTelegramIx, StartEndFilterSamplesCount2); } }
+        /// Test end time for metrology in seconds
+        public double TimestampSecEnd { get { return TimeFromSamples(optoData, optoDataCount, TestEndTelegramIx, StartEndFilterSamplesCount2); } }
+
+        ///
+        /// Indices to determine centers of start / end samples
+        ///
+        public int TestStartTelegramIx;
+        public int TestEndTelegramIx;
         int endTelegramIdx1;
         int endTelegramIdx2;
         int endTelegramIdx3;
 
         int currentTelegramIx;
         bool startSampleAcquired;
-        public int TestStartTelegramIx;
-        public int TestEndTelegramIx;
 
 
 		OptoTelegramRaw[] optoData;
@@ -589,23 +591,11 @@ namespace TBF.Rig.TestMethods.iPerlCommunication.iPerlHead
             {
 				/// Take the test start sample
                 startSampleAcquired = true;
-                volumeLtrStart = volumeLtr;
-                timestampSecStart = timestampSec;
                 TestStartTelegramIx = currentTelegramIx;
             }
             else if (startSampleAcquired)
             {
                 /// Shift data in pipelines
-                volumeLtrEnd = volumeLtrEnd3;
-                volumeLtrEnd3 = volumeLtrEnd2;
-                volumeLtrEnd2 = volumeLtrEnd1;
-                volumeLtrEnd1 = volumeLtr;
-
-                timestampSecEnd = timestampSecEnd3;
-                timestampSecEnd3 = timestampSecEnd2;
-                timestampSecEnd2 = timestampSecEnd1;
-                timestampSecEnd1 = timestampSec;
-
                 TestEndTelegramIx = endTelegramIdx3;
                 endTelegramIdx3 = endTelegramIdx2;
                 endTelegramIdx2 = endTelegramIdx1;
@@ -650,7 +640,7 @@ namespace TBF.Rig.TestMethods.iPerlCommunication.iPerlHead
 			{
 				resultCode |= (int)Results.Entities.ResultCode.MissingOptoData;
 			}
-			else if (volumeLtrEnd == volumeLtrStart)
+			else if (VolumeLtrEnd == VolumeLtrStart)
 			{
 				resultCode |= (int)Results.Entities.ResultCode.OptoDataWithZeroFlow;
 			}
@@ -967,6 +957,63 @@ namespace TBF.Rig.TestMethods.iPerlCommunication.iPerlHead
             }
         }
 
+        /// <summary>
+        /// Calculate a filtered volume from data stream samples
+        /// </summary>
+        /// <param name="unwrappedIx">Samples used in calculation are centered around unwrappedIx</param>
+        /// <param name="samplesCount2">Count of samples used in calculation is 2 * smaplesCount2 + 1</param>
+        /// <returns>Filtered volume</returns>
+        double VolumeFromSamples(OptoTelegramRaw[] optoData, int optoDataCount, int unwrappedIx, double scalingFactor, int samplesCount2 = 0)
+        {
+            if (samplesCount2 < 0) samplesCount2 = 0;
+            if ((unwrappedIx - samplesCount2) < 0 || (unwrappedIx + samplesCount2) >= optoDataCount) return 0;
+
+            Int64 sum = 0;
+            for (int i = unwrappedIx - samplesCount2; i <= unwrappedIx + samplesCount2; i++)
+            {
+                int wrappedIx = OptoTelegramRaw.BufferIdx(i);
+
+                if (optoData[wrappedIx].Flags != OptoTelegramFlags.OK &&
+                    optoData[wrappedIx].Flags != OptoTelegramFlags.OK_TestStart &&
+                    optoData[wrappedIx].Flags != OptoTelegramFlags.OK_TestEnd)
+                {
+                    return 0;
+                }
+
+                sum += optoData[wrappedIx].VolumeRawExt;
+            }
+
+            return 0.0000625 * scalingFactor * sum / (double)(2 * samplesCount2 + 1);
+        }
+
+        /// <summary>
+        /// Calculate a filtered time from data stream samples
+        /// </summary>
+        /// <param name="unwrappedIx">Samples used in calculation are centered around unwrappedIx</param>
+        /// <param name="samplesCount2">Count of samples used in calculation is 2 * smaplesCount2 + 1</param>
+        /// <returns>Filtered time</returns>
+        double TimeFromSamples(OptoTelegramRaw[] optoData, int optoDataCount, int unwrappedIx, int samplesCount2 = 0)
+        {
+            if (samplesCount2 < 0) samplesCount2 = 0;
+            if ((unwrappedIx - samplesCount2) < 0 || (unwrappedIx + samplesCount2) >= optoDataCount) return 0;
+
+            Int64 sum = 0;
+            for (int i = unwrappedIx - samplesCount2; i <= unwrappedIx + samplesCount2; i++)
+            {
+                int wrappedIx = OptoTelegramRaw.BufferIdx(i);
+
+                if (optoData[wrappedIx].Flags != OptoTelegramFlags.OK &&
+                    optoData[wrappedIx].Flags != OptoTelegramFlags.OK_TestStart &&
+                    optoData[wrappedIx].Flags != OptoTelegramFlags.OK_TestEnd)
+                {
+                    return 0;
+                }
+
+                sum += optoData[wrappedIx].TimestampExt;
+            }
+
+            return sum / (double)(8192 * (2 * samplesCount2 + 1));
+        }
 
         public void WriteBinary(BinaryWriter writer)
         {