Performance evaluation of NIM GPS receivers in use for time transfer with PTB

Two self-developed GPS receivers of NIM (National Institute of Metrology), which are based on a Javad E_GGD receiver and a NovAtel OEMV3 receiver, respectively, have been installed and operated at PTB (Physikalisch-Technische Bundesanstalt) for a time transfer link calibration between both institutes. During the operation of the traveling receivers at PTB for several weeks, their performances have been thoroughly evaluated. A subset of the results of general interest is presented. From the results we decided on the most suitable mode of operation of the NIM GPS traveling receivers. The uncertainty of the link calibration will potentially be influenced by the temperature sensitivity of the receivers, which was thus investigated. Finally, we studied the receiver internal delay as a function of time and its installation in the host laboratory.