Datasheet

Page 14
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Average only mode
Number of averages 1 2 4 8 16 32 64 128 256 512 1024
Noise multiplier
Normal mode 2.0 1.8 1.7 1.5 1.0 0.95 0.74 0.55 0.39 0.29 0.21
x2 mode 2.7 2.4 2.0 1.6 1.0 0.91 0.78 0.53 0.34 0.29 0.20
Effect of time-gating and averaging on normal mode measurement noise:
The normal mode measurement noise wil depend on the gate length (time-gated period in
second) and the number of averages. The noise can be approximately calculated with the
following equations.
If the gate length is < 2.73 µs, use Equation 1:
Noise = Noise per sample
×
1
Number of averages
Otherwise, use Equation 2:
Noise = Noise per sample
×
1
×
4
1/4
Number of averages
(
Gate length/(0.68 µs)
)
Note: If the noise value obtained from Equation 1 or 2 is lower than the measurement noise
specification, use the value as specified in the measurement noise table.
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 of averages, to determine the total measurement noise value.
Example:
U2000A power sensor, –60 to –35 dBm, normal mode, number of averages = 4
Measurement noise calculation:
1 nW x 1.7 = 1.7 nW
Specifications (Continued)