The FS740 GPS Time and Frequency System provides a 10 MHz frequency reference with a long-term stability of better than 1 × 10-13. A built-in receiver tracks any of the four major GNSS constellations: GPS, GLONASS, BEIDOU, or GALILEO. The instrument can also time tag external events with respect to UTC or GPS and measure the frequency of user inputs. The instrument has DDS synthesized frequency outputs, adjustable rate (and width) pulse outputs, and an AUX output for arbitrary waveforms including an IRIG-B timecode output.