LBXXXA Series USB Powe
™
Product Manual PMA (Power Meter Application)
Revision: 08/02/11
- 42 -
NOTE:
Selecting dB Relative as the units of measurement will disable limits. The Limits Setup diaglog box does not
include a dB Relative selection.
Measurement Accuracy
The sources of measurement uncertainty associated with the LB series of power sensors consist of the following error
terms:
1. Mismatch
2. Calibration factor
3. Linearity
4. Noise
5. Temperature
6. Zero Offset
A root-sum-of-the-squares (RSS) uncertainty computation of these error terms yields an overall measurement
accuracy of ± 1.95%. This is based on a well matched DUT where source match and calibration factor are the
dominant contributors to uncertainty.
RSS =
√ (Mm² + CF² + L² + N² + T² + Z²)
+1.95% = 10 log (1+0.0195) = +0.084 dB
- 1.95% = 10 log (1- 0.0195) = - 0.086 dB
The plot below represents the total uncertainty relative to the input bandwidth for the
Powe™ line of products.
