The Cs clock transition frequency is compared
against the maser flywheel frequency. The acquired offset Cs yH is used to correct the classical timescale TS(Cs) generated from the maser utilizing a phase stepper (Df). An equivalent scheme is applicable when referencing the timescale TS(Sr)
to an optical frequency standard. For that purpose, the clock laser light is down-converted to the microwave regime using a femtosecond frequency comb (FC) before comparing against the flywheel. Moreover, both maser offsets can be analyzed to
yield the Sr clock frequency in SI units.