Anritsu 37 C Series, Operation Manual

Page: 176 / 603

Averaging is another way to improve accuracy. The improvement is
proportional to the square root of the number of averages. The im-
provement from averaging, however, comes at the expense of increased
sweep time.
Figure 8-11 shows the measured reduction in noise due to bandwidth
and averaging.
Example: Using 1 kHz BW reduction and 10 averages, you would in-
crease the signal-to-noise ratio by 7.6 dB but would lengthen the time
required for the measurement by a factor of 4.3. This example as-
sumes a constant signal power.
LOW LEVEL AND GAIN MEASUREMENTS
8-16 37XXXC OM
M E A S U R E M E N T S O N A 7 0 d B A T T E N U A T O R
A L L D A T A N O R M A L I Z E D T O
A 1 k H z I F B A N D W I D T H A N D 1 A V E R A G E
R E L A T I V E
N O I S E ( d B )
N U M B E R O F A V E R A G E S
7 . 0
3 . 5
1 . 4
. 3 5
. 1 4
1 2 5 1 0 2 0 5 0 1 0 0 2 0 0 5 0 0
1 0 K H z ( I F B W )
1 K H z
1 0 0 H z
. 7
Figure 8-11. Reduction in Noise Using Averaging
AVERAGING
Up to 4096 Averages
Reduces Noise
Increases Sweep Time