Fig. 1. Transmission delay characteristic of unit length optical fiber link

Fig. 2. Schematic diagram of optical fiber link temperature measurement system

Fig. 3. Flow chart of optical fiber link temperature measurement system

Fig. 4. Segmented temperature model of optical fiber time synchronization link

Fig. 5. Temperature change of each section of optical fiber link within 24 hours

Fig. 6. Simulation results of 100-km optical fiber link. (a) Round-trip delay；(b) unidirectional transmission delay；(c) equivalent average temperature

Fig. 7. Estimation accuracy of 100-km one-way delay. (a) Without considering Time interval counter resolution，(b) considering Time interval counter resolution

Fig. 8. Physical diagrams of experimental platform. (a) Terminal equipment and optical fiber link；(b) temperature control box

Fig. 9. Round-trip delay and temperature of temperature control box

Fig. 10. Round trip delay after Kalman filtering

Fig. 11. Temperature of temperature control box and estimated temperature of link

Fig. 12. Estimated link temperature