NEO-M8P RTK Accuracy

Hi all,

It is indicated that the accuracy is 2.5 cm + 1 ppm.

What means this “1 ppm” ? Is this part per million related to the distance between the base station and the rover ?

GPS Accuracy = error + (ppm error x distance from rover to base) .
Example 30mm + 2 ppm , distance = 5km = 5000000 mm.
GPS Accuracy = 30mm+ 2x5000000x0.0000001 (part-per-million)= 30mm+10mm. = 40mm.
I attach some document here:

Thank you for your reply.