#define STARTING_LATITUDE_LONGITUDE_ALTITUDE NULL
uint8_t internalANT[]={0xB5,0x62,0x06,0x13,0x04,0x00,0x00,0x00,0xF0,0x7D,0x8A,0x2A};
uint8_t externalANT[]={0xB5,0x62,0x06,0x13,0x04,0x00,0x01,0x00,0xF0,0x7D,0x8B,0x2E};


...
  
setup() {
 

    // select internal antenna
    //antennaSelect(internalANT);
    antennaSelect(externalANT); 
  
}



void antennaSelect(uint8_t *buf){
    for(uint8_t i=0;i<12;i++)
    {
        Serial1.write(buf[i]); //send the command to gps module
        Serial.print(buf[i],HEX);
        Serial.print(",");
    }
    Serial.println("");
}