Agilent Technologies 346A Operating And Service Manual page 13

General Information
Introduction
Excess Noise Ratio Expanded Uncertainty (U(Y)) - Table 1-2
ENR values are given at cardinal frequency points over the frequency
range of each noise source. These ENR values are printed on the noise
source label and on a separate printed report supplied with the 346
Noise Source. Included in the printed report is the measurement
uncertainty for each cardinal frequency point.
A significant proportion of the expanded uncertainty (U(Y)) is based on
the uncertainties provided by the United States National Institute of
Standards and Technology (NIST) and/or The United Kingdom National
Physics Laboratories (NPL). Agilent therefore reserve the right to
change the overall expanded uncertainties based on changes in
uncertainty values within the National Standards Institutes.
Uncertainties are valid at ambient temperature 23°C ±1°C (296K) only.
A typical characteristic plot of ENR (U(Y)) versus each cardinal
frequency point is shown in Figure 1-1. the uncertainties given are
typical - refer to the printed calibration report for the actual
uncertainties for your noise source.
1
Figure 1-1 Characteristic ENR Plot versus Cardinal Frequency Points
1. Characteristic values are met or bettered by 90% of instruments with 90% confidence.
6 Chapter 1