Symmetricom 5071A, Operating And Programming Manual

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Chapter 6 Specifications
Footnotes
116 Operating and Programming Manual
Time Domain Stability: (also called short-term
stability); The standard deviation of fractional
frequency fluctuations in the specified output
signal due to random noise in the cesium standard.
The mathematical method by which it is calculated
is called the Root Allan Variance. Symbolically, it
is represented by the term y (2, ) where y is the
standard deviation, 2 means that measurements are
taken in pairs, and is the measurement time.
In the 5071A specifications, values for all
averaging times are shown in one chart for
convenience. However, short-term stability
specifications for averaging times in excess of
1000 seconds are valid only under laboratory
conditions (temperature 25 ±5 C, relative humidity
45% ±10%). For more information on time
domain stability, see NIST Technical Note 1337,
Characterization of Clocks and Oscillators
available from the Superintendent of documents,
U.S. Government Printing Office, Washington
D.C. 20402-9325.