I want to check the noise level of pseudorange of UBLOX receivers (NEO 8T). I put two receivers at the same location with a clear sky. From my knowledge, the double difference should be like noise. However, when I calculated the double difference of Pseudorange, I found there were periodic patterns in them. The maximum is about 10 meters, and the period is around 50 secs. Can you please tell me why this happened?
This is not caused by the reference satellite. If I changed the reference satellite, the problem remained.Note that the pseudorange is obtained from RAWX messages.