10-20-2010 08:38 AM
Hi all,
USB 6215 DAQ board uses16-bit analog to digital conversion. Is it possible here to set lower bit conversion e.g. that DAQ board works only with 12-bit A/D conversion on particular input analog channels. Thanks in advance for your help.
tommy
10-21-2010 02:39 AM
Hi Tommy,
Could you please let us know why you would like 14 bit resolution, and why 16 bit would represent an issue?
Thank you,
Mircea
10-21-2010 02:49 AM
Hi,
I want change conversion resolution because I want to use 3-parameter sine-fitting algorithm to check A/D. Actually, I want to show how A/D resolution may affect measured signal in frequency domain. I know, sine-fitting methods are based in time domain, but also the same acquired signal I want to represent in frequency domain at different A/D resolution. But I seems to me that thica can not be set as easy way or not? Thank you for your replies on this.
Have a nice day,
Tommy
10-21-2010 03:05 AM
Hi,
The resolution of the ADC cannot be phisically changed, as it is in HW.
On the other hand , the SW component is more flexible, so you could transform your 16 bit signal into 14 bit.
The easiest would be to make the two LSBs 0.
If I might have a recommendation, if you use LV for sine-fitting, have in mind the vi: Extract Single Tone Information.
Good luck,
Mircea
10-21-2010 03:08 AM
Thank you for the tip.I will try this.
Have a nice day,
Tommy
10-21-2010 02:38 PM
Here is a link to a shipping example that shows how you can convert a DBL into a calibrated, unscaled binary number. You'll probably want to modify it to use 16-bit numbers instead of 32-bit.
You can then use LabVIEW's And Function (it performs a bitwise AND on numeric inputs) to mask out the last two bits like Mircea suggested. Assuming you modify the example to use 16-bit integers, you should use 0x FFFC (1111 1111 1111 1100) as your mask to set the last two bits to 0.
Best Regards,
10-22-2010 12:15 AM
Thank you,
that is I was looking for. Simple and efficient way.