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Time and Frequency Metrology

NIST's 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.

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.

NIST's Time and Frequency Metrology Group activities include:

  • 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

Calibration Services

The Time and Frequency Metrology Group is engaging in new programs in spectrum analysis and calibration services for industrial, military, and commercial organizations. PM /AM noise measurements require traceability and certification of microwave components such as oscillators, amplifiers, etc. The following calibration services are provided by the group:

PM/AM Noise Measurement Systems

News and Updates


NIST Time and Frequency Bulletin

Kathryn R. Stephenson
The Time and Frequency Bulletin provides information on performance of time scales and a variety of broadcasts (and related information) to users of the NIST



Group Leader

Calibration Leader

Project Leader