In this paper, a novel and efficient photonic-assisted remote frequency measurement (RFM) system with significantly simplified structure flexible operation range is proposed. system, the antenna unit (RAU) central station (CS) are separated to ensure concealment safety of signal processing unit. At RAU, unknown radio (RF) modulated by dual-polarization dual-drive Mach–Zehnder modulator (DPol-DM...

In this contribution we focus on laser frequency noise properties and their influence on the interferometric displacement measurements. A setup for measurement of laser frequency noise is proposed and tested together with simultaneous measurement of fluctuations in displacement in the Michelson interferometer. Several laser sources, including traditional He-Ne and solid-state lasers, and their ...

We report a high-accuracy direct measurement of the blackbody radiation shift of the 133Cs ground-state hyperfine transition. This frequency shift is one of the largest systematic frequency biases encountered in realizing the current definition of the International System of Units (SI) second. Uncertainty in the blackbody radiation frequency shift correction has led to its being the focus of in...

In previous publications, a new echo-ranging Doppler system based on transmission of repetitive coherent frequency-modulated ͑FM͒ sinusoids in two different implementations was presented. One of these implementations, the frequency-modulated–frequency-shift measurement ͑FM–fsm͒ Doppler system is, in this paper, compared with its pulsed-wave counterpart, the pulsed-wave– time-shift measurement ͑PW–ts...

The accurate monitoring of blade vibration under operating conditions is essential in turbo-machinery testing. Blade tip timing (BTT) is a promising non-contact technique for the measurement of blade vibrations. However, the BTT sampling data are inherently under-sampled and contaminated with several measurement uncertainties. How to recover frequency spectra of blade vibrations though processi...

Introduction:  The  use  of  mobile  communication  systems  has  dramatically  increased  over  the  past  decade. Although many studies have been performed to determine the effect of radio frequency (RF) but  less attention has been paid to the possible biological impact of exposure to extremely low frequency  (ELF) components.   The objective of this study is two folds. One is to design the ...

This paper surveys the instrumentation, calibration procedures, measurement techniques, and standards which can be used to characterize extremely low frequency (ELF) electric and magnetic fields. While the focus of the paper is on power frequency and power frequency harmonic fields, the measurement methods discussed are appropriate in principle for other ELF frequencies.

A monolithic resonance frequency readout circuit with high resolution and short measurement time is presented for a 900 MHz RF surface acoustic wave (SAW) sensor. The readout circuit is composed of a fractional-N phase-locked loop (PLL) as the stimulus source to the SAW device and a phase-based resonance frequency detecting circuit using successive approximation (SAR). A new resonance frequency...

Optical frequency combs can be employed over a broad spectral range to calibrate laser frequency or vacuum wavelength. This article describes procedures and techniques utilized in the Precision Engineering Division of NIST (National Institute of Standards and Technology) for comb-based calibration of laser wavelength, including a discussion of ancillary measurements such as determining the mode...