Reliable operation of GNSS, PNT, and satellite communication systems is built on a stable, continuously available time and frequency reference. From GNSS 1PPS timing and network synchronization, through holdover when external references are degraded, to the timing core and RF LO reference inside satellite communication systems, different system states call for different classes of local time base and control architecture. Taitien provides TCXOs, VCTCXOs, OCXOs, GNSSDOs, atomic clocks, and timing modules, helping equipment manufacturers build the right GNSS timing, Resilient PNT, and SATCOM timing solution around stability, phase noise, vibration, power, operating temperature, and holdover requirements.