Atec Agilent-U2000 Series - Manual (Page 14)

14
Specifications (continued)
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.
Average only Mode
Number of averages 1 2 4 8 16 32 64 128 256 512 1024
Noise multiplier
Normal
mode
x2 mode
2.0
2.7 1.8
2.4 1.7
2.0 1.5
1.6 1.0
1.0 0.95
0.91 0.74
0.78 0.55
0.53 0.39
0.34 0.29
0.29 0.21
0.20
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
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 Ч
1
Ч
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 measure-
ment noise table.