Omega-vehicle-security OMP-MODL Manuel d'utilisateur télécharger pdf (Page 285)

11.. . APPENDIX F: FILTERING OPTIONS

USING THE OMP-MODL 11-123

APPENDIX F: FILTERING OPTIONS

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.

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Omega-vehicle-security OMP-MODL Manuel d'utilisateur Page 285