post processing using NI6225

[Clint Eastwood]

Kevin,

The vi moves whole rows.  What about individual elements ?

[Kevin_Price]

I'm not sure quite what you're asking.  If some elements can remain in their original position, you can just make sure that the values of the map array at those indices are equal to the index value.  That'll map them right back to the same place.

If instead there are only a few elements that need to be changed at all and most of them remain in their original position, the mapping can probably be done more efficiently a different way.  For example, the mapping array would have elements that are a cluster of 'source' and 'destination' index values.  Then you would auto-index on the mapping array, and only operate on values that need to be moved.

Generally, try some things out.  Experiment.  Get to understand how the mapping works.  Maybe you need to do something different than I guessed, but hopefully I've at least illustrated a way to begin thinking about a solution...

-Kevin P.

[starfox_maicon]

    Clint, can you help me? I want to do a undersampling with NI 6259 to a signal         with 1MHz but I don´t know to much about it. Can you give me some tips?
    Perhaps, some place on internet where I find good material about it.
    Thanks!

    starfox_maicon

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@Clint Eastwood wrote:

Let me revisit the undersampling and get back to you.  Can you check this Discussion Grp periodically ?

Clint E.

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[Clint Eastwood]

This project was over a year ago.  Let me see if I still have the developmental code and I'll post it.

Clint

[Clint Eastwood]

"starfox" see if this helps.  Like I said its been over a year since I did this.  I remember going back and forth with Ryan ( see previous posts).  He was very knowledgable and very helpful.  If I remember right I had to oversample to get all my 900 channels to read at once as the 6225 shares a A/D per card.  I triggered on an external analog signal ( PFI0).  Once the trigger was acquired it fired off the READ on each card, hence, each channel.  Oversampling preserved the amplitude ( which I was interested in) but not necessarily the freq.  I can't remember if each card reads a single sample then goes on to the next channel, reads a sample etc OR each channel reads all data at once then goes to the next channel.  It would make more sense to do the former.

Hope this helps.  If your still having trouble I would start with my previous posts and get an applications eng from National on the line.  Those guys are amazing at their knowledge of their products.

Clint

[ryan_d]

Hi Starfox,

I just wanted to let you know that I am the AE monitoring this thread. If you have any difficulties with Clint Eastwood’s suggestions, please post back. Have a great day!

[Clint Eastwood]

Hi Ryan ( again !),

Do you remember this project ??  Did we oversample or undersample ??  I think I undersampled because of the amount of cards/channels.  Undersampling would have made sense.

[ryan_d]

Hello everyone,

I’m actually a different Ryan! I have read through this thread, though, so I’m familiar with the project. Clint, you undersampled your signal.

Reply number 29 of 47 on page 3 by Kevin Price thoroughly explains how to undersample a signal. Also, reply number 22 of 47 on page 3 by Ryan V explains that M Series boards, in this case the 6225, only have one ADC and therefore have multiplexed input. This was the reason Clint needed to undersample. I recommend reading those posts and the rest of this thread, since there was some excellent discussion and a desirable solution was reached.

Have a great day!