Datasheet
Page 9
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Performance Characteristics (continued)
Zero set, zero drift and measurement noise
Sensor model Sensor option Range Conditions (RH)
1
Zero set
4
Zero drift
2, 4
Measurement noise
3, 4
N8481A, N8482A,
N8485A, N8487A,
N8486AR, N8486AQ
Standard Upper up to 70% ±63 nW < ±7 nW < 114 nW
Lower up to 70 % ±25 nW < ±3 nW < 80 nW
Option CFT N/A
5
up to 70% ±63 nW < ±7 nW < 114 nW
N8488A Standard Upper up to 70% ±63 nW < ±7 nW < 114 nW
Lower up to 70 % ±25 nW < ±3 nW < 80 nW
Option CFT N/A
5
N/A
5
N/A
5
N/A
5
N/A
5
N8481B, N8482B Standard Upper up to 70% ±63 μW < ±7 μW < 114 μW
Lower up to 70 % ±25 μW < ±3 μW < 80 μW
Option CFT N/A
5
up to 70% ±63 μW < ±7 μW < 114 μW
N8481H, N8482H Standard Upper up to 70% ±6.3 μW < ±0.7 μW < 11.4 μW
Lower up to 70 % ±2.5 μW < ±0.3 μW < 8 μW
Option CFT N/A
5
up to 70% ±6.3 μW < ±0.7 μW < 11.4 μW
1. RH is the abbreviation for relative humidity.
2. Average hourly drift, at constant temperature. If there is an abrupt change of temperature, it is strongly recommended to perform zeroing or waiting for
30 minutes before taking the measurement.
3. The number of averages at 16 for normal mode and 32 for x2 mode, at a constant temperature, measured over one-minute interval and two standard
deviations.
4. The zero set, zero drift, and measurement noise specifications are tested at 50 MHz.
5. N/A is the abbreviation for “not applicable.”
Effects of averaging on noise
Averaging over 1 to 1024 readings is available for reducing noise. The table below
provides the measurement noise for a particular sensor with the number of averages
set at 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.
Example:
N8481A power sensor, normal mode, number of averages = 4
Measurement noise calculation:
< 80 nW x 2.75 = < 220 nW
Number of averages 1 2 4 8 16 32 64 128 256 512 1024
Noise multiplier
Normal mode 5.5 3.89 2.75 1.94 1 0.85 0.61 0.49 0.34 0.24 0.17
x2 mode 6.5 4.6 3.25 2.3 1.63 1 0.72 0.57 0.41 0.29 0.2