Filtering - Contrec 202A User Manual

3.4 FILTERING

Frequency fluctuations caused by pulsating flow through a flowmeter, often
makes the Rate impossible to read with any precision.
The Model 202A has a digital filter which will average out these fluctuations
and enable the Rate to be read to four digit accuracy. The ability to select a
suitable filtering level means that highly accurate and stable readings can be
obtained without excessive lag.
The diagram below shows a pulsating signal input together with the effect
of filtering.
As a guideline to the degree of filtering to be used, the following table shows
the response to a step change in input. The value, CAL 06, is the filter
constant which is programmed during the Programming routine. The times
for the display value to reach 90% and 99% of full swing are given in seconds,
for different values of CAL 06.
P rogramming
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