Sensitivity to the External Temperature of Some GPS Time Receivers

摘要

It has been assumed until recently that GPS time receiver units (receiver+cables+antenna) have good stability and do not affect time transfer by more than 1 ns. Differences of a few nanoseconds sometimes observed during calibration campaigns have been attributed to external causes, such as multipath propagation, rather than to variations within the hardware. The characteristic feature of most comparisons of GPS time receivers is their short duration. Normally the comparison takes place, at most, over one week. To observe the behavior of GPS time receivers over a period of several months, an experiment has been organized involving three receivers of two types. All three were connected to the same atomic clock. An unexpected sensitivity to external temperature war found in one type of receiver. The effect proved to be a function of the length and type of the antenna cable. In the most unfavorable case the sensitivity was 1.8 ns/deg C.