NAWGIS and KODGIS are dedicated for useres which require higher accuracy, than one can obtain from raw GNSS signals but do not need accuracies provided by RTK/RTN solutions. Those services are designed for L1 recivers working on code solutions.

Within KODGIS and NAWGIS services L1 code GPS and GLONASS observations for Virtual Reference Stations (VRS) are sent to the users rover. The main difference between both services lies within position of computed VRS:

1. KODGIS service needs current rovers position sended via NMEA GGA message. Afterwards a VRS observations are computed for received coordinates.
2. NAWGIS service is computing observations for two predefined VRS sites. Therefore no NMEA GGA message is requested.

The NAWGIS_Polnoc stream contains GNSS observations for VRS located in northern Poland, while NAWGIS_Poludnie is dedicated for southern region of Poland.

Our tests show repeatability of measured coordinates within ± 0.25 m for KODGIS stream and within ± 3 m for NAWGIS ones.