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Input Filtration
Peak filter
This filter is intended for eliminating
pulse spikes (peaks), which can appear
in the input signal, in the following way:
♦
BBI250 measures the input signal value
every 120 ms (sample time).
♦
The measured values are compared
subsequently. The filter checks
the difference between the last
2 samples. If it does not exceed
Gradient value, the device accepts
the signal as normal.
♦
If the last measured value differs
from the previous one by more than
the Gradient value, the filter output
is held until the device determines
a presence of a normal signal.
It is possible only if the input signal
has not been changed with more than the
Gradient value for 4 subsequent samples.
♦
If the device has not determined
a normal signal for 20 subsequent
samples, noi appears on the display
(see 'Basic level').
Low-pass filter
This first-order filter acts ONLY within
a certain band around filter output value.
This has been designed to cut periodic
noises outside the communication signal
spectrum.
♦
Filter operation is defined by two
parameters:
Filter Time (defines filter time constant) and
Filter Band (defines filter active band around
filter output value).
♦
If the newly measured value differs
from the filter output by more than
Filter Band, the filter resets
with a new initial output value
(newly measured value).
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