Omega Vehicle Security OMP-MODL - Manual (Page 285)

11.. . A PPENDIX F: F ILTERING O PTIONS
U SING THE OMP-MODL 11-123
A
PPENDIX
F: F
ILTERING
O
PTIONS
Many of the Interface Modules can be configured with filtering options for reducing
the noise picked up on sensor or input signal wiring. A short discussion of two of the
filtering methods that are available to the User through icon configuration dialog
boxes follow:
ADC Input Filtering
In the OMP-MODL, a first order noise filter can be enabled within many of the
analog input icon configuration dialog boxes. First order filtering reduces High
frequency noise that may be picked up by sensor wiring. However, filtering slows
down the rate at which a channel can be sampled as it adds additional settling time
to the total time required for a reading.
Additional settling time required for each of the three levels is specified in the table
below.
If speed of execution of the Program Net is not of concern, utilize the High level of
filtering for best noise rejection.
Filter Level Additional Settling Time
None 0
High 15 mS
50Hz / 60Hz Sofware Filtering
Noise radiated from utility power lines (including house and building wiring,
appliances and extension cords) and picked up by sensors and associated wiring is
one of the most common sources of data acquisition error.
The OMP-MODL has additional software based filtering capability designed to
remove 50 Hz or 60Hz power line sourced noise from incoming signals. This
filtering capability is especially helpful in applications with sensors and/or wiring
which is in close proximity to utility wiring.