Specifications

Power Meter Supplemental Characteristics

Zero Drift of Sensors

Power sensor dependent (refer to Table 5-3).

Measurement Noise

Power sensor dependent (refer to Table 5-2 and Table 5-3).

Averaging effects on measurement noise. Averaging over 1 to 1024 readings is available for reducing noise. Table 5-3 provides the measurement noise for a particular power sensor with the number of averages set to 16 for normal mode and 32 for x2 mode. Use the “Noise Multiplier” for the appropriate mode (normal or x2) and number of averages to determine the total measurement noise value.

For example, for an HP 8481D power sensor in normal mode with the number of averages set to 4, the measurement noise is equal to:

(<45 pW x 2.75) = <124 pW

Table 5-2: Noise Multiplier

Number of

 

1

2

4

8

16

32

64

128

256

512

1024

Averages

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Noise Multiplier

 

5.5

3.89

2.75

1.94

1.0

0.85

0.61

0.49

0.34

0.24

0.17

(Normal Mode)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Noise Multiplier

 

6.5

4.6

3.25

2.3

1.18

1.0

0.72

0.57

0.41

0.29

0.2

(x2 mode)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

HP EPM-442A User’s Guide

5-7