The problem can be diagnosed by following procedure. -Check whether indicator lights are blinking. If not, then check power supply system, e.g. whether the wire is well connected. -Check whether Precis output NMEA data. If not, configure output of Precis with configuration tools. -Check NMEA data, if NMEA does not contains valid data, e.g. $GPGGA,051502.00,,,,,0,00,99.99,,,,,,*7B, then check whether antenna is connected to Precis. -Check NMEA sentence $GPGGA, if the GPS status section in $GPGGA sentence is 1, and then it means Tersus/Precis is working in point position mode, then check the status of RTCM data stream. If GPS status section is 4 or 5, it means Tersus/Precis is working in relative positioning mode and everything goes well. If the GPS status is 4, then you get centimeter level RTK fixed solution. If the GPS status is 5 then you get sub-meter level RTK float solution. Remark: the seventh section in $GPGGA sentence in the GPS status, which is after ‘E’ o