Rubidium Atomic Frequency Standards

FEI builds Rubidium Atomic Frequency Standards for mission critical solutions for Space, Land, Sea and Air applications in Assured Position Navigation and Timing (APNT), Electronic Warfare (EW) and Time Distribution. FEI has in-house production capabilities of vapor cell production using rubidium chloride to produce atomic clocks and other quantum sensing devices.

Frequency Electronics Inc. (FEI) provides Rubidium Atomic Frequency Standards (RAFS), which are highly accurate and stable frequency references used in various critical applications. Key aspects of FEI’s Rubidium Atomic Frequency Standards:


Rubidium Atomic Frequency Standards offer precise time and frequency references based on the natural resonance frequency of rubidium atoms. These standards utilize the hyperfine transition of electrons in rubidium atoms, which provides a stable and accurate frequency output. The technology ensures minimal drift and high stability over time.



    • Telecommunications: Used in network synchronization, ensuring reliable and consistent communication signals.
    • Defense and Aerospace: Essential for navigation systems, communication, radar, and other military applications requiring precise timing.
    • Space Systems: Provide accurate timing for satellite operations, including GPS and other global navigation satellite systems (GNSS).
    • Scientific Research: Serve as precise frequency references in various research applications, including metrology and timekeeping.


Features and Benefits

    • High Stability: FEI’s rubidium standards offer excellent short-term and long-term stability, reducing frequency drift and ensuring consistent performance.
    • Low Phase Noise: Critical for applications requiring clean signal generation and high signal integrity.
    • Compact and Durable: Designed to be compact and robust, suitable for both ground-based and spaceborne applications.
    • Long Operational Life: Engineered for reliability and longevity, reducing the need for frequent maintenance or replacement.


FEI’s Rubidium Atomic Frequency Standards are essential for applications demanding high precision and stability. Their products are trusted by industries and organizations worldwide for their reliability, performance, and advanced technology.

Digital Rubidium Atomic Frequency Standard (DRAFS) for GPS III and GPS IIIF performance

GPS III Space Vehicle 10 (SV10) has the FEI Digital Rubidium Atomic Frequency Standard (DRAFS) clock on board. One of FEI DRAFS engineering development units (EDU) is included in SV10s experimental/future clock slots for evaluation after completion of qualification testing of our qual unit. FEI’s DRAFS provides excellent frequency stability designed for the space environment.

Pulsed Optically Pumped Rubidium Atomic Frequency Standard (POPRAFS) 7-day holdover clock

The Pulsed Optically Pumped Rubidium Atomic Frequency Standard (POPRAFS) clock technology employs a pulsed laser light source locked to an optical transition in a separate Rb vapor cell, to prepare the atoms and probe the atomic transitions.  Using a laser improves clock performance by eliminating the need for a Rubidium plasma lamp a technology with inherent performance limitations, and enabling the interrogation of the atoms using a pulsed (Ramsey) scheme that reduces the sensitivity of the clock to the AC Stark shift by an order of magnitude.

Timing Unit Rubidium Oscillator (TURBO)

The Timing Unit Rubidium Oscillator (TURBO) includes timing requirements that cannot be met with quartz oscillator technology alone. Fractional frequency stability and accuracy requirements better than 3 x 10-12   𝝉-𝟏/𝟐   for 100s averaging times as well as time holdover requirements better than ±10μs over 1 day require the use of an atomic clock. All stability and accuracy requirements in addition to phase noise requirements must also be met when the unit is subjected to airborne operational vibration levels.

Search by Products & Solutions

→ Search by Products & Solutions

Please visit our Products & Solutions page or call 516-794-4500 for more information.

FEI Provides Products and Solutions Used by
Government Agencies and Companies Since 1961

Frequency Electronics, Inc.

Precision Time & Frequency
(Space, Sea, Land, Air)

Read More

FEI-Elcom Tech

Microwave Modules & Subsystems


Read More

FEI-Zyfer Inc.

GPS Position, Navigation, Time & Frequency Reference Systems

Read More