USB-6211 delta-modulation

[CKOMOPOX]

Hello everyone,

I have DAQ NI USB-6211 (http://sine.ni.com/nips/cds/view/p/lang/en/nid/203190) with witch help i need to create delta-modulation (http://en.wikipedia.org/wiki/Delta_modulation ). I was trying to do it ,but i don't know how to transformed input data (binary data type) convert to a graph data(dbl for example). I need that if signal is logic "1", then graph signal grow for one level, but if signal is logic "0", than graph signal decrease for one level.If anyone know the details please share it.

Regards

Jurijs

[ManLongAtNI]

Hello Jurijs,

Keep in mind Delta modulation, as stated in your above link evaluates an analog signal "with a series of segments. Each segment of the approximated signal compared to the" previous segment to modulate the signal. It appears from the attached code, you are probably not segmenting the data points appropriately to do a proper comparison.

What is the intended application, in which case performing this task in software may not be applicable.

[CKOMOPOX]

When what should I do? There is some other methode to make this exercise?

[ManLongAtNI]

Do you wish to only perform the software delta modulation or hardware delta modulation?

What is the intended application?

[CKOMOPOX]

I need it for hardware. I am trying to create virtual distance labrotory.

[ManLongAtNI]

Hello Jurijs,

I'm still unclear on you application. There are several NI Data Acquisition Devices, specifically the DSA (Dynamic Signal Acquisition) boards that uses a delta-sigma modulating ADC. If you would like a board that samples in this manner I can recommend some boards depending on your application.

Or, since this is for a virtual distance laboratory, were you looking for a vi that demonstrated the behavior of the delta-modulating ADC, similar to the following link?

(Quick Look) Filters and Delta Sigma Converters

[CKOMOPOX]

I don't speak english so good,that is why I will try to explain my aim by using the picture. Today's step is create a VI, which can acquire data from generator and convert it to 1-bit stream,which will be recreated in the same VI(real part is only a signal from generator).

[ManLongAtNI]

Hello CKOMOPOX,

It appears you want to visually see the digital representation of your analog signal. If that is the case navigate to the following pallette, Programming>>Waveform Analog to Digital.vi. There is also a Digital to Waveform.vi to the opposite manipulation. 

[CKOMOPOX]

Message Edited by CKOMOPOX on 02-11-2010 04:40 AM