I’ve been testing the HAS performance of a stationary UM980 receiver under good GNSS receiving conditions and am seeing some quirks. The biggest is a convergence error of about 1/3 a meter in longitude. Given multiple hours the average longitude reported will be about 35cm to the east. I’ve seen this with multiple days of data. Latitude and height values are typically biased less than a decimeter. Has anyone else seen this?
I have done several days of testing with a Septentrio Mosaic board being fed by the same antenna as the Unicore board and recorded the raw HAS corrections to be processed with HASLIB as detailed here:
The latitude, longitude, and height values of the Mosaic data processed with RTKLIB in PPP kinematic mode do not show the large longitude bias.
I’m recording a NMEA GGA sentence every 15 seconds from the Unicore board to look at its position output along with raw data to determine the exact coordinates.
I’m in the center of North America if that matters. Again, has anyone seen something similar?