diff --git a/DS4Windows/DS4Library/Crc32.cs b/DS4Windows/DS4Library/Crc32.cs
index b07ff7c..14d10ea 100644
--- a/DS4Windows/DS4Library/Crc32.cs
+++ b/DS4Windows/DS4Library/Crc32.cs
@@ -203,7 +203,80 @@ namespace DS4Windows
             return crc;
         }
 
-        public static uint CalculateHash(ref uint seed, ref byte[] buffer, ref int start, ref int size)
+        public static uint CalculateBasicHash(ref uint seed, ref byte[] buffer, int offset, int size)
+        {
+            uint crc = seed;
+            int i = offset;
+            while (size >= 16)
+            {
+                uint one = (buffer[i++] |
+                            (uint)(buffer[i++] << 8) |
+                            (uint)(buffer[i++] << 16) |
+                            (uint)(buffer[i++] << 24)) ^ crc;
+                uint two = buffer[i++] |
+                            (uint)(buffer[i++] << 8) |
+                            (uint)(buffer[i++] << 16) |
+                            (uint)(buffer[i++] << 24);
+                uint three = (buffer[i++] |
+                            (uint)(buffer[i++] << 8) |
+                            (uint)(buffer[i++] << 16) |
+                            (uint)(buffer[i++] << 24));
+                uint four = buffer[i++] |
+                            (uint)(buffer[i++] << 8) |
+                            (uint)(buffer[i++] << 16) |
+                            (uint)(buffer[i++] << 24);
+
+                crc = secondLook[15, one & 0xFF] ^
+                    secondLook[14, (one >> 8) & 0xFF] ^
+                    secondLook[13, (one >> 16) & 0xFF] ^
+                    secondLook[12, (one >> 24) & 0xFF] ^
+                    secondLook[11, two & 0xFF] ^
+                    secondLook[10, (two >> 8) & 0xFF] ^
+                    secondLook[9, (two >> 16) & 0xFF] ^
+                    secondLook[8, (two >> 24) & 0xFF] ^
+                    secondLook[7, three & 0xFF] ^
+                    secondLook[6, (three >> 8) & 0xFF] ^
+                    secondLook[5, (three >> 16) & 0xFF] ^
+                    secondLook[4, (three >> 24) & 0xFF] ^
+                    secondLook[3, four & 0xFF] ^
+                    secondLook[2, (four >> 8) & 0xFF] ^
+                    secondLook[1, (four >> 16) & 0xFF] ^
+                    defaultTable[(four >> 24) & 0xFF];
+
+                size -= 16;
+            }
+
+            while (size >= 8)
+            {
+                uint one = (buffer[i++] |
+                            (uint)(buffer[i++] << 8) |
+                            (uint)(buffer[i++] << 16) |
+                            (uint)(buffer[i++] << 24)) ^ crc;
+                uint two = buffer[i++] |
+                            (uint)(buffer[i++] << 8) |
+                            (uint)(buffer[i++] << 16) |
+                            (uint)(buffer[i++] << 24);
+                crc = secondLook[7, one & 0xFF] ^
+                    secondLook[6, (one >> 8) & 0xFF] ^
+                    secondLook[5, (one >> 16) & 0xFF] ^
+                    secondLook[4, one >> 24] ^
+                    secondLook[3, two & 0xFF] ^
+                    secondLook[2, (two >> 8) & 0xFF] ^
+                    secondLook[1, (two >> 16) & 0xFF] ^
+                    defaultTable[two >> 24];
+
+                size -= 8;
+            }
+
+            while (--size >= 0)
+            {
+                crc = (crc >> 8) ^ defaultTable[(crc & 0xFF) ^ buffer[i++]];// i++;
+            }
+
+            return crc;
+        }
+
+        public static uint CalculateFasterBTHash(ref uint seed, ref byte[] buffer, ref int start, ref int size)
         {
             /*uint crc = seed;
             for (int i = start; i < size + start; i++)
diff --git a/DS4Windows/DS4Library/DS4Device.cs b/DS4Windows/DS4Library/DS4Device.cs
index dcedb20..423c350 100644
--- a/DS4Windows/DS4Library/DS4Device.cs
+++ b/DS4Windows/DS4Library/DS4Device.cs
@@ -447,7 +447,7 @@ namespace DS4Windows
 
             touchpad = new DS4Touchpad();
             sixAxis = new DS4SixAxis();
-
+            Crc32Algorithm.InitializeTable(DefaultPolynomial);
             refreshCalibration();
         }
 
@@ -468,12 +468,45 @@ namespace DS4Windows
             }
         }
 
+        const int DS4_FEATURE_REPORT_5_LEN = 41;
+        const int DS4_FEATURE_REPORT_5_CRC32_POS = DS4_FEATURE_REPORT_5_LEN - 4;
         public void refreshCalibration()
         {
             byte[] calibration = new byte[41];
             calibration[0] = conType == ConnectionType.BT ? (byte)0x05 : (byte)0x02;
-            hDevice.readFeatureData(calibration);
-            sixAxis.setCalibrationData(ref calibration, conType == ConnectionType.USB);
+
+            if (conType == ConnectionType.BT)
+            {
+                bool found = false;
+                for (int tries = 0; !found && tries < 5; tries++)
+                {
+                    hDevice.readFeatureData(calibration);
+                    uint recvCrc32 = calibration[DS4_FEATURE_REPORT_5_CRC32_POS] |
+                                (uint)(calibration[DS4_FEATURE_REPORT_5_CRC32_POS + 1] << 8) |
+                                (uint)(calibration[DS4_FEATURE_REPORT_5_CRC32_POS + 2] << 16) |
+                                (uint)(calibration[DS4_FEATURE_REPORT_5_CRC32_POS + 3] << 24);
+
+                    uint calcCrc32 = ~Crc32Algorithm.Compute(new byte[] { 0xA3 });
+                    calcCrc32 = ~Crc32Algorithm.CalculateBasicHash(ref calcCrc32, ref calibration, 0, DS4_FEATURE_REPORT_5_LEN - 4);
+                    bool validCrc = recvCrc32 == calcCrc32;
+                    if (!validCrc && tries >= 5)
+                    {
+                        Log.LogToGui("Gyro Calibration Failed", true);
+                        continue;
+                    }
+                    else if (validCrc)
+                    {
+                        found = true;
+                    }
+                }
+
+                sixAxis.setCalibrationData(ref calibration, conType == ConnectionType.USB);
+            }
+            else
+            {
+                hDevice.readFeatureData(calibration);
+                sixAxis.setCalibrationData(ref calibration, conType == ConnectionType.USB);
+            }
         }
 
         public void StartUpdate()
@@ -691,7 +724,6 @@ namespace DS4Windows
                 CRC32_POS_3 = BT_INPUT_REPORT_CRC32_POS + 3;
             int crcpos = BT_INPUT_REPORT_CRC32_POS;
             int crcoffset = 0;
-            Crc32Algorithm.InitializeTable(DefaultPolynomial);
 
             while (!exitInputThread)
             {
@@ -725,10 +757,10 @@ namespace DS4Windows
                             (uint)(btInputReport[CRC32_POS_2] << 16) |
                             (uint)(btInputReport[CRC32_POS_3] << 24);
 
-                        uint calcCrc32 = ~Crc32Algorithm.CalculateHash(ref HamSeed, ref btInputReport, ref crcoffset, ref crcpos);
+                        uint calcCrc32 = ~Crc32Algorithm.CalculateFasterBTHash(ref HamSeed, ref btInputReport, ref crcoffset, ref crcpos);
                         if (recvCrc32 != calcCrc32)
                         {
-                            Log.LogToGui("Check failed", true);
+                            Log.LogToGui("Crc check failed", true);
                             //Console.WriteLine(MacAddress.ToString() + " " + System.DateTime.UtcNow.ToString("o") + "" +
                             //                    "> invalid CRC32 in BT input report: 0x" + recvCrc32.ToString("X8") + " expected: 0x" + calcCrc32.ToString("X8"));