Enable/Disable Anti Alias Filter on PCI-4472

[AStephenson]

I am trying to control the Anti Alias filter on a PCI-4472.  The help file describes a boolean property AI.EnhancedAliasRejectionEnable and suggests for 447x it is disabled by default.  I have created a voltage channel and successfully used it to capture data and  I have queried the property and it returns false at a variety of sample rates.  However when I try to set it to true I get an error -200355 "Hardware does not support it" .  The anti alias filter is in all the specification documentation I can find for this card so I am at a loss as to wether or not the filter is actually on or off and how if possible to control it.

All suggestions welcome.

Many Thanks. Andy

[Sarah_Coleman_NIUK]

Hi Andy,

The anti-aliasing filter, is part of the analog to digital converter (ADC) and cannot be turned off. You can find lots of information on the 4472 filters in the following manual:
http://forums.ni.com/attachments/ni/231/4196/1/322940b%5B1%5D.pdf

Why do you want to be able to control this filter?

[AStephenson]

Hi Sarah

Thankyou for your reply.

My application is for an experimental mass spectrometer.  The operators suspect noise in the signal generated by one of the many power supplies and would like raw data to help pinpoint which one.  In normal operation this would not be a requirement and I have other data capture cards and scopes I can hook up if required but the help I downloaded "NI Dynamic Signal Acquisition Help - Low-Frequency Alias Rejection" suggested it could be controlled on 447x cards and I wondered if I was creating the channel in the wrong manner or if I needed set some other property first.  This is my first application using National Instruments suite so I suspected an error in my code.

Cheers! Andy

Message Edited by AStephenson on 09-29-2006 06:01 AM

[Sarah_Coleman_NIUK]

Hi Andy,

I think I know the property you're referring to. Is the attached JPEG the document you read?

The property allows you to control a suplementory filter for these devices that allows you to filter out low frequencies. The page displayed in the JPEG describes this low frequency anti aliasing filter in more detail.

If you need to measure the raw data from the device you would probably be better using one of your other scopes.

Hope this clarifies things!