Verification of transfer functions of co-located Superconducting Gravimeters in time and frequency domain

The analysis of the system response to added step and/or sine wave functions allows for an empirical, non-parametric description of the transfer function. The parallel operation of two co-located superconducting gravimeters (SG) over periods of more than two years allows to verify the validity of these estimates. The group delay at the zero frequency is an important parameter for tidal analysis. The stability over frequency of group and phase delay of the systems is discussed in the frequency domain and verified by correlation analysis in time domain. Finally, the parallel observations allow to estimate minimum length of comparison periods for relative scale factor transfer between different sensors under the presence of colored noise.