[skip navigation] NIST Home Page NIST Physics Laboratory Home Page NIST Time and Frequency Division Home Page
  Radio Stations
  Time Transfer

Time and Frequency Metrology Group


The oscillating, or repeating, signal that is the basis for constructing all signals is a voltage that exactly follows simple periodic sine and cosine functions of time. The synthesis of such signals, using an oscillator coupled with a "frequency synthesizer" can never be perfectly realized because the voltages from these devices are perturbed by random noise from real electronic components.

Frequency synthesis plays a role in virtually all present-day commercial, industrial, and military technologies. State-of-the-art low-noise frequency synthesis is a particularly important technical asset to high-speed telecommunications, efficient management of the wireless spectrum, and high-resolution imaging. It is worth noting that overall performance of various technologies depends on, and is often limited by, phase and amplitude noise fluctuations in oscillators and frequency synthesizers.

NISTís Time and Frequency Metrology Group has the world's most advanced measurement and calibration facilities for characterizing noise components in oscillators and frequency synthesizers. It engages in many activities to determine the cause of various kinds of noise for the purpose of isolating and reducing it, leading to improved components, instruments and techniques that are often necessary in new applications.

Activities include:
    1) measurements of oscillator phase noise (equivalently, relative time-fluctuation noise), and associated amplifiers and passive-devices, for government, commercial, industrial, and military users,
    2) technical training, mentoring, and consulting through seminars, workshops, and on-site visitations and facility inspections,
    3) certification of phase and time-fluctuation noise measurements of national metrology laboratories,
    4) technology transfer, primarily with respect to oscillators, measurement systems, and analysis techniques, to insure best performance, consistency, and accuracy in specifications.

As steady state phase noise becomes lower and lower, temperature fluctuations, acceleration, and other environmental effects, cause various phase instabilities. To augment the Group's phase noise metrology program, we have expanded characterization of oscillator and other-device environmental sensitivity to include vibration and acceleration sensitivity. A fast-growing concern in future electronics systems is that acceleration sensitivity causes vibration-induced noise that coincides with a critical range of offset frequencies relative to an oscillator's carrier frequency.

The Time and Frequency Metrology Group has a responsibility for:

  • Measurements
         -- PM and AM Noise
         -- Clock Jitter
         -- Spectrum
         -- Frequency and Time Stability

  • Data Analysis
         -- Allan and Total frequency variances
         -- Jitter Histogram
         -- Fourier Transform
         -- Kalman Filter

  • Calibration
         -- Tunable Noise and SSB-Tone Standards
         -- Frequency (Atomic Frequency Reference)
         -- Beat Frequency (Heterodyne and Dual Heterodyne)

  • Component
         -- Oscillators
         -- Amplifiers
         -- Synthesizers
         -- Digital Clocks and Logic Devices
         -- Frequency Standards

  • Instrumentation
         -- 1 kHz to 110 GHz
         -- 1 x 10-15 frequency stability
         -- Clock Jitter down to 10 femtoseconds
         -- L(f) down to -177 dBc/Hz for 0 dBm signal at room temperature


    Optoelectronic Oscillators
    Vibration Sensitivity Measurements
    W-band Frequency Synthesis and AM/PM Noise Measurement System
    Pulsed X-Band PM/AM Noise Measurement Systems
    Frequency Synthesis for Atomic Standards
    Phase and Amplitude Noise Measurements
    Clock Ensemble Prediction Algorithms
    Description of Calibration Services
    Time Domain Stability Statistics


    Properties Of Oscillator Signals And Measurement Methods
    Publications Lookup


      Staff contact information

      Time and Frequency Division
      National Institute of Standards and Technology
      325 Broadway
      Boulder, Colorado 80303, USA
      FAX: (303) 497-6461

  • Questions? Send an email to David Howe of the Phase Noise Measurement Group.