Ratios of S/N and TOA uncertainty values for PSR J1730-2304 as a function of time. Signal-to-noise ratio (S/N) and TOA uncertainty values (σ) were derived from NUPPI observations at 1.4 GHz, calibrated using the IFA method and the calibration method presented in Sect. 3. Individual NUPPI observations were fully integrated in time and integrated in frequency so as to form eight sub-bands of 64 MHz each. TOAs whose uncertainties are shown in this figure were extracted from individual observations using the FDM algorithm (see Sect. 4.1 for additional details on the analysis, and Appendix B for equivalent figures for the other analyzed MSPs).