diff --git a/Telemetry.cpp b/Telemetry.cpp
index aa6c4fe2..2f9a1da3 100644
--- a/Telemetry.cpp
+++ b/Telemetry.cpp
@@ -226,8 +226,12 @@ void inline send_GPS_speed(void)
       uint16_t Data_GPS_speed_ap;
       uint16_t temp;
       if (f.GPS_FIX && GPS_numSat >= 4) {           
-         temp = (GPS_speed * 40 + 102) / 203;                       // FRSKY specific format in knots => factor ~50 (102 for rounding purpose)
-         Data_GPS_speed_bp = temp / 10;
+         #if defined KILOMETER_HOUR                                        // OPENTX specific format in kilometers per hour => factor 36/100 (will be devided by 10 later)
+             temp = (GPS_speed * 36) / 10; 
+         #else                                                             // FRSKY specific format in knots => factor ~50 (will be devided by 10 later)
+             temp = (GPS_speed * 40) / 203; 
+         #endif
+         Data_GPS_speed_bp = temp / 10;                                    // here comes the devision by 10
          Data_GPS_speed_ap = temp - Data_GPS_speed_bp * 10;
          sendDataHead(ID_GPS_speed_bp);
          write_FrSky16(Data_GPS_speed_bp);
diff --git a/config.h b/config.h
index 92dce2c3..dffdfa1e 100644
--- a/config.h
+++ b/config.h
@@ -880,26 +880,30 @@ Also note, that maqgnetic declination changes with time, so recheck your value e
   /********************************************************************/
   /****                             TELEMETRY                      ****/
   /********************************************************************/
+    // select one of the two protocols depending on your receiver
     //#define FRSKY_TELEMETRY           // used for FRSKY twoway receivers with telemetry (D-series like D8R-II or D8R-XP) 
                                       // VBAT, Baro, MAG, GPS and POWERMETER are helpful
                                       // VBAT_CELLS is optional for a forth screen on the display FLD-02
     //#define SPORT_TELEMETRY           // for FRSKY twoway receivers with S.PORT telemetry (S-series like X4R/X6R/X8R), not implemented yet - TO BE DONE
 
-    // A2 voltage is represented by a value in the range 0-255.
-    // So if you set the max for A2 to be 12.4 each step will increase the displayed voltage by ~0.0486
-    #define FRSKY_SPORT_A2_MAX 124    // NOTE: VBAT gets stored as an integer.  16 would be 1.6V, 124 is 12.4V, etc etc
-   
+    // FRSKY common entries - valid for both protocols
     #define TELEMETRY_SERIAL 3        // change if required
-    #define COORDFORMAT_DECIMALMINUTES // uncomment to get the format DD°MM.mmmm for the coordinates - comment out to get the format DD.dddddd° for the coordinates 
+
+    // FRSKY standard telemetry specific devices
     #define FRSKY_FLD02               // send only data specific for the FRSKY display FLD-02
-                                      // comment out for OpenTX and Er9x, all data will be sent via FRSKY protocol
     //#define OPENTX                    // send OpenTX specific data
-    //#define ER9X                      // send Er9x specific data, not implemented yet - TO BE DONE FOR THE FUTURE
+
+    // FRSKY standard telemetry specific selections
+    //#define COORDFORMAT_DECIMALMINUTES // uncomment to get the format DD°MM.mmmm for the coordinates - comment out to get the format DD.dddddd° for the coordinates 
+    //#define KILOMETER_HOUR            // send speed in kilometers per hour instead of knots (default) - requested by OPENTX
     #define TELEMETRY_ALT_BARO        // send BARO based altitude, calibrated to 0 when arming, recommended if BARO available
     //#define TELEMETRY_ALT_GPS         // send GPS based altitude (altitude above see level), for FLD-02 don't use together with TELEMETRY_ALT_BARO
     #define TELEMETRY_COURSE_MAG      // send MAG based course/heading, recommended if MAG available, but FLD-02 does not display
     //#define TELEMETRY_COURSE_GPS      // send GPS based course/heading, don't use together with TELEMETRY_COURSE_MAG, FLD-02 does not display
 
+    // S.PORT specific entries
+    #define FRSKY_SPORT_A2_MAX 124    // A2 voltage is represented by a value in the range 0-255. A value of 16 results in 1.6V, 124 is 12.4V, etc
+
   /********************************************************************/
   /****                             Buzzer                         ****/
   /********************************************************************/