NI 6713: how much memory will 1 waveform take?

[Wan81]

Hi Guys,

I really need some help to know whether the product I wanna purchase is the correct one.

1. In layman terms, can someone explain how much memory or samples will it take to describe 1 waveform?

2. 6713 has 128KB of memory right?

3. Is 128KB of memory enough to create a simple arbritary waveform of about 100kHz? Or In other words, how much memory will it take to create an arbritary waveform?

4. Is there a separate software needed to create an arbritary waveform

Will appreciate if there's any literature regarding how much memory needed and the technique employed to create the waveforms etc..

Best,

Ridwan

[NI-Bongo]

Hi Ridwan,

Generally, the number of samples it takes to describe a waveform depends on the accuracy desired.  You will need to update at a minimum of the Nyquist frequency, which is twice the highest frequency component contained in the waveform. I would do a google or wiki search for Nyquist Theorem if you are not familiar with it.  In your case, this is 200kHz, but this is the absolute minimum requirement to maintain the frequency desired, not the shape.  If you tried to generate a 100kHz sine wave with a 200kHz update rate, it would look like a triangle wave.  To reproduce the shape of a waveform, at least 8-10 times the highest frequency component of the waveform should be used as an update rate.

The 6713 specifications actually tell you update rate in samples per second, so you don’t need to do the calculation of how much memory is needed.  Here are the specs:
http://www.ni.com/pdf/manuals/371011c.pdf

To calculate the memory required, take the number of samples in the waveform and multiply by 12 to get the amount of memory needed in bits to generate the waveform on the 6713.  If you use a different device, multiply by the bit depth of the device (for a 16-bit device, multiply by 16).

To generate the waveform, you can input values into a table or generate a standard function in software, or you can purchase the NI Analog Waveform Editor to do more advanced creation and editing.  Let me know if you’d like me to have someone contact you about this.

I hope this answers your questions!

Regards,

[NI-Bongo · Accepted solution]

Hi Ridwan,

Here's a link to the NI Analog Waveform Editor product page:
http://sine.ni.com/nips/cds/view/p/lang/en/nid/13631

Regards,