Fig. 1. Schematic diagram of test timekeeping system based on ⁴⁰Ca⁺ optical clock

Fig. 2. Schematic diagram of ⁴⁰Ca⁺ optical clock

Fig. 3. Running rates of ⁴⁰Ca⁺ optical clock and whole system

Fig. 4. Self-compared frequency deviation of ⁴⁰Ca⁺ optical clock

Fig. 5. Self-compared frequency stability of ⁴⁰Ca⁺ optical clock

Fig. 6. Frequency stability of hydrogen maser clock

Fig. 7. Frequency drift rate of hydrogen maser clock

Fig. 8. Schematic diagram of frequency steering method based on ⁴⁰Ca⁺ optical clock

Fig. 9. Schematic diagram of frequency steering method based on UTC

Fig. 10. Frequency deviation between ⁴⁰Ca⁺ optical clock down-conversion frequency and hydrogen maser clock frequency

Fig. 11. Fractional frequency deviation of hydrogen maser clock estimated by ⁴⁰Ca⁺ optical clock

Fig. 12. Steering frequencies on microphase stepper

Fig. 13. Time difference between UTC and TS(Ca)/TS(H)/UTC(PTB)

Fig. 14. Frequency stabilities of TS(Ca), TS(H) and UTC(PTB)