Statistical characteristics of L1 carrier phase observations from four low-cost GPS receivers

Statistical properties of L1 carrier phase observations from four low-cost GPS receivers are investigated through a case study. The observations are collected on a zero baseline with a frequency of 1 Hz and processed with a double difference model.
The carrier phase residuals from an ambiguity fixed solution and zero baseline coordinate components computed on an epoch-by-epoch basis are used for accessing the statistical properties of the observations. Graphical statistical methods are used for characterizing the statistical properties.
For each type of receiver, the residuals have a sample mean value close to zero and the sample variance is time invariant. The residuals from one type of receiver deviate from being normally distributed, whereas the residuals from the remaining receivers are close to being normally distributed. Two of the receivers deliver uncorrelated carrier phase observations. Some of the carrier phase observations from the other two receivers are serially correlated. The correlation is receiver specific and is related to the individual channels of the receivers.