AVL F-FEM-DDC - 4.3.2 Spikefilter

Operation
38
F-FEM-DDC — User’s Guide
4.3.2 Spikefilter
This filter is eliminating pulses that are shorter than the minimal pulse length.
The minimal pulse length is taken from the "Range max raw" (f max) column of
the group Counter Inputs within the FFS Block in the Parameter Manager PAM
and working in the following way:
Pulses (high or low) < 1 / (f max * 10) are ignored.
This gives a cutoff frequency (with 50 % duty cycle) of
f
cut
= 0.5 / t
min
Exaample of one Spike:
For more details please see the F-FEM-Parameterization Users Guide.
The minimum pulse length is t
min
= 1 / (500 * 10) = 200 µs
The cutoff frequency for this example gives f
cut
= 0.5 / 200 µs = 2500 Hz
Fig. 16
Example
A signal is feeding the digital input channel 3, and the counter Input of channel 2
is parameterized as:
S.Type = Digital In,
S.Attrib. = Frequ A_unsigned,
Marks = 1,
AcquRate = 100 Hz,
Range Check Raw = User defined,
Range max raw = 500 Hz