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Stanford FS725 Benchtop Rubidium Frequency Standard

Home Products Instrumentation Time and Frequency Stanford FS725 Benchtop Rubidium Frequency Standard

Stanford FS725 Benchtop Rubidium Frequency Standard

Stanford Research Systems

The FS725 benchtop rubidium frequency standard from Stanford Research Systems integrates a rubidium oscillator (Stanford model PRS10), a low noise universal AC power supply, and distribution amplifiers in a compact half-width 2U chassis. It provides stable and reliable performance, with an estimated 20 year aging of less than 5 x 10-9 and a demonstrated rubidium oscillator MTBF of over 200,000 hours.


  • 10MHz and 5MHz outputs
  • 20 year aging less than 0.005ppm
  • Ultra low phase noise (<-130dBc/Hz at 10Hz)
  • Built-in distribution amplifiers (up to 22 ouputs)
  • 1pps input and output for GPS synchronisation
  • RS232 computer interface
  • Two status alarm relays

There are two 10MHz and 5MHz outputs with exceptionally low phase noise of -130dBc/Hz at 10Hz offset and low one second Allan Variance of <2 x 10-11. The 1pps output has less than 1ns of jitter and may be set with 1ns resolution.

Up to three internal distribution modules can be added to the FS725. Each module has four 10MHz outputs, one 5MHz output and one 1pps output, all with the same low phase noise, harmonic distortion and jitter.

In most cases the FS725 will be used as a stand-alone frequency standard due to its extremely low aging. However, it can also be phase-locked to an external 1pps reference (like GPS) for Stratum 1 performance.

An RS-232 interface allows direct communication with the rubidium oscillator. Using the provided Windows software you can easily monitor and control 1pps timing and determine the instrument's operational status.

There are two alarm relays that indicate the rubidium oscillator lock state and its synchronisation to an external 1pps input. The relays are SPDT providing both normally-open and normally-closed operation.

The FS725 is an ideal instrument for calibration and R&D laboratories, or for any application requiring a precision frequency standard. You can now inexpensively deploy accurate frequency references throughout a facilty.

For further information please contact us or download the datasheet.


          FS725 datasheet                                              Read more on Stanford's website