10 Hz or 10 s?

Abstract

Data sampling frequencies in many kinematic GNSS applications are often in the range of 2–10 Hz or even higher. In contrast, the sampling frequency of standard reference stations is usually not higher than 1 Hz, and many stations even deliver data at sampling intervals as large as 30 s. An easily implemented algorithm for data interpolation will be presented and it will be demonstrated that interpolation of pseudorange and carrier phase reference station data is possible at a high level of accuracy. This technique—which has not received proper attention so far—is helpful to reduce data storage capacity for postprocessing applications, but and can also be beneficial for real-time applications suffering from slow data links. Results of test trials indicate that a standard deviation better than 2 mm can be reached for interpolated carrier phases collected at reference sites sampling data with 5-s intervals in double difference mode. These interpolated double difference data obviously still follow a Gaussian distribution. A trend function for the expected standard deviation of interpolated double difference carrier phase measurements will be presented. From this function, a recommendation for an optimal sampling rate of reference station data can be derived which is close to 10 s.