Tutorial Session 1B - Introduction to Quartz Frequency Standards

Abstract

This tutorial reviews the subject of digital measurements of clocks and oscillators. It focuses primarily on the precision measurement of phase and the use of these measurements in estimating phase and frequency and common statistics such as the Allan deviation and the spectral density of phase. The subject matter includes direct counting, interpolating counters, dividers, heterodyne conversion, and dual-mixer systems. Biases in the measurements caused by aliasing and measurement quantization are evaluated. Analog techniques, which are used primarily to evaluate phase noise, are covered in a related tutorial.Samuel R. Stein is founder and President of Timing Solutions Corporation, a company that specializes in real-time applications and that provides timing systems to National Laboratories, DoD programs such as GPS, and Government Prime Contractors. He has developed ultra high precision time measurement, generation and distribution systems and is an internationally recognized leader in time and frequency measurement methods and the ensembling of clocks. He was previously

Clock Synchronization with Deterministic Accuracy Guarantee

“…For these reasons, we have measured these values in the actual nodes to assess how reasonable these assumptions are. Since temperature is the primary cause that affects the clock frequency [22], we measure the frequency under different temperatures.…”

Radiation sensitivity of microelectromechanical system devices

“…This effect can be as large at 10 ppm for natural quartz at a 1-Mrad dose. 38 Pure crystals are much less affected.…”

“…37 Though not strictly speaking a MEMS device, the sensitivity of quartz resonators to radiation has been studied, and a review can be found in Ref. 38. The resonance frequency of a quartz resonator changes with radiation, because the elastic properties are modified when radiation changes the position of weakly bound charge compensators ͑such as H + , Li + , or Na + ͒ around substitutional defects, which also reduces the quality factor.…”

Physical-Layer Network Coding Using FSK Modulation under Frequency Offset

“…The frequencies generated by crystal oscillators are offset from ideal specifications due to manufacturing imperfections, ambient conditions such as temperature and radiation level, as well as aging of the oscillator [3]. In this work, oscillator offsets are modeled as real values added to the frequencies of the FSK tones generated by the sources which are constant for all symbol periods, representing the case of fixed ambient conditions over a time scale short enough to neglect the effects of oscillator aging.…”