diff --git a/M8_cfg_gnss.c b/M8_cfg_gnss.c
index 1dde118..5d78d18 100644
--- a/M8_cfg_gnss.c
+++ b/M8_cfg_gnss.c
@@ -4,16 +4,17 @@
 //****************************************************************************
 
 uint8_t ubx_cfg_gnss[] = { // Full spectrum enabling GPS, GLONASS, SBAS, QZSS and GALILEO, disable BEIDOU/IMES
-  0xB5,0x62,0x06,0x3E,0x3C,0x00,
-  0x00,0x00,0x20,0x07,
-  0x00,0x08,0x10,0x00,0x01,0x00,0x01,0x01,
-  0x01,0x01,0x03,0x00,0x01,0x00,0x01,0x01,
-  0x02,0x04,0x08,0x00,0x01,0x00,0x01,0x01,
-  0x03,0x08,0x10,0x00,0x00,0x00,0x01,0x01,
-  0x04,0x00,0x08,0x00,0x00,0x00,0x01,0x01,
-  0x05,0x00,0x03,0x00,0x01,0x00,0x01,0x01,
-  0x06,0x08,0x0E,0x00,0x01,0x00,0x01,0x01,
-  0x30,0xAD };
+  0xB5,0x62,0x06,0x3E,0x3C,0x00, // header (SYNC1, SYNC2, MsgCls, Id, 2byte-len)
+  0x00,0x00,0x20,0x07, // msgVer, numTrkChHw(ro), numTrkChUse, numConfigBlocks)
+  //Id,Tr  ,MxTr,rsv , enb, rsv,chsh,rsv   // actual field names: gnssId, resTrkCh, maxTrkCh, reserved1, flags(X4, little-endian)
+  0x00,0x08,0x10,0x00,0x01,0x00,0x01,0x01, // GPS
+  0x01,0x01,0x03,0x00,0x01,0x00,0x01,0x01, // SBAS
+  0x02,0x04,0x08,0x00,0x01,0x00,0x01,0x01, // Galileo 
+  0x03,0x08,0x10,0x00,0x00,0x00,0x01,0x01, // BeiDou
+  0x04,0x00,0x08,0x00,0x00,0x00,0x01,0x01, // IMES
+  0x05,0x00,0x03,0x00,0x01,0x00,0x01,0x01, // QZSS
+  0x06,0x08,0x0E,0x00,0x01,0x00,0x01,0x01, // GLONASS
+  0x30,0xAD }; // check-sum, ANY changes to above values requires update
 
 SendUBLOX(hUARTGPS, sizeof(ubx_cfg_gnss), ubx_cfg_gnss); // Use sizeof() for array, strlen() will catch the NULs