Early_NBS_crystal_oscillator_frequency_standards.jpg
Summary
Description Early NBS crystal oscillator frequency standards.jpg |
English:
Four precision 100 kHz quartz
crystal oscillators
maintained by the US Bureau of Standards (now the
National Institute of Standards and Technology
that served as the frequency standard for the United States in 1929. Built by
Bell Telephone Laboratories
, where the quartz crystal oscillator was invented in 1923, they achieved a frequency stability of 10
-7
. The oscillators are enclosed in temperature controlled ovens kept at a precisely constant temperature to prevent thermal expansion and contraction of the quartz resonator, which would cause changes in frequency. The large crystal resonators are mounted under the glass domes visible on top of the units.
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Date | |
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Author | Unknown author Unknown author |
Licensing
Public domain Public domain false false |
This image is in the
public domain
in the United States because it is a
work of the United States Federal Government
, specifically an employee of the
National Institute of Standards and Technology
, under the terms of
Title 17, Chapter 1, Section 105 of the
US Code
.
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