Conventional GNSS satellites have high-performance atomic oscillators onboard, with accuracy being controlled and maintained from the ground stations. Furuno’s GF series is a Multi-GNSS Disciplined Oscillator (GNSSDO) which is capable of receiving GNSS satellite signals and outputting highly precise time pulse (1PPS) and reference frequency. The GF series can also learn the behavior of its own oscillators (TCXO or OCXO) and adjust its output using GNSS signals to achieve better accuracy at a substantially lower cost than an atomic oscillator (Rubidium or Cesium). Another advantage over the atomic oscillator is that periodical calibration is not required since GNSSDO compensates time pulse and reference frequency continuously by using GNSS signals. The GNSSDOs are used extensively in large infrastructures requiring precise time, and reference frequency and time synchronization, such as digital terrestrial broadcast base stations, cell phone base stations and wireless communication network systems.