PSI System Controls and Diagnostics
F3200E User Manual
F3200E_UM_180726 Page 101 of 107
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Optimizing data quality
As with all measurement devices, the F3200E is subject to tradeoffs between noise and
bandwidth. It is capable of making wideband measurements at sampling rates of up to 1 MSa/s
and low-pass analog roll off at 250 kHz. However you should always ask yourself whether this
bandwidth is needed for your application. If you can narrow the bandwidth, you will improve the
signal to noise ratio of your data.
The F3200E provides flexible on-board averaging of the ADC values to allow you to tailor the
measurement bandwidth to your needs. Measurements have shown that the noise level,
expressed as a fraction of the full scale current, is almost independent of the current range in use.
The following graph shows how the unloaded noise of the device changes as you increase the
amount of averaging, from no averages (1 conversion per sample, 1 M samples per second) up to
10000 (10000 conversions per sample, 100 samples per second).
0.0001%
0.0010%
0.0100%
0.1000%
1.0000%
1
10
100
1000
10000
Conv/Sa
RM
S
noi
se
% FS
10mA range
1mA range
100uA range
10uA range
Figure 78. Noise level as a function of averaging
Note that block averaging of this type is a rectangular filter in the time domain. The resulting
frequency domain response has zeroes at N * [(ADC Rate) / (Conversions/Sample)] Hz, where N
= 1, 2, 3, …
