The FS740 from Stanford Research Systems is a GPS/GNSS Time and Frequency Standard that provides a 10 MHz frequency reference. It has long-term frequency stability of 1 × 10-13, short-term frequency stability of 1 × 10-9, and phase noise of less than -100 dBc/Hz at 10 Hz offset. The instrument has a built-in receiver that can track GPS, GLONASS, BEIDOU, or GALILEO constellations. It can also time tag external events with respect to UTC or GPS and measure the frequency of user inputs. It provides DDS synthesized frequency output, adjustable-rate (and width) pulse output, and an AUX output for arbitrary waveforms including an IRIG-B timecode output.
The FS740 has an optional OCXO that provides short-term frequency stability of 1 × 10-11 with a phase noise of less than -130 dBc/Hz at 10 Hz offset. It also has an optional rubidium timebase that provides short-term frequency stability of 1 × 10-12 with a phase noise of less than -130 dBc/Hz at 10 Hz offset.
The FS740 has a screen at the front with a graphical user interface that allows users to configure the instrument and see the results of time and frequency measurements. It is available in an enclosure that measures 8.5 × 3.5 × 13.0 inches and has ethernet/USB control interfaces. The instrument requires an AC supply of 90-264 V, 47-63 Hz with PFC, and consumes 90 W of power.