how do i know the available sampling rates of my Digitizer card

[1113215]

hi,

i m using pci-5105 , i want to know what are the sampling rates available to me for data acquisition.

regards 

umair

[Wallace_F]

Hello Umair,

The sampling rate for your PCI-5105 is 60 MS/sec for all channels, as your digitizer performs simultaneous sampling.  For more detailed information, you can view the NI PXI/PCI-5105 Specifications or the NI High-Speed Digitizers Help document.

Best wishes,

Wallace F.

[1113215]

wallace,

Thanks 4 reply, yeah the maximum sampling rate available is 60MSPS, but the issue is that i want to know "all the available sampling rates ".

 1- I have been acquiring data using various sampling rates lesser than 10MSPS. mostly  i got results of the same sampling rate as desired, but recently as i acquired data

with 27 MSPS but the card acquired it at 30MSPS i.e. sampling rate was coerced that is why i want to know what are the rates availble to me as it seems i cant acquie on all sampling rates according to my wishe. hope u get me.

2- Refering to PCI5105 specifications document , under the heading Sample clock at pg-10, it says

"Divide by n decimation used for all rates less than 60 MS/s"

where 1 ≤ n ≤ 65,535

which gives sampling rates as 60M,30M,20M,15M,12 M, 10M, 8.5714M and so on. does this mean these are   available sample rates???

please correct me if i m wrong????

regards,

umair

[DFGray]

You are correct.  If you specify a rate that is not one of the actual sampling rates, it will be coerced upwards.  This is the reason the NI-SCOPE (and IVI) API specifies the sample length in period by default, not samples.  At a faster sampling rate, you need more samples to get the same data interval.  For your card, there are 65, 535 sample rates in the range {60M, 30M, 20M, 15M, ... , 915.555, 915.541}.  They get pretty close together at the end.  Most digitizers sold by NI have similar architectures.

[Jennifer O]

I just wanted to add that if you need a specific sample rate such as 27MHz, you also have the option to use an external clock. 

You can provide your own 27MHz clock signal via the PFI line on the front panel and specify it as your sample clock.  The external sample clock can also be decimated by a factor n to achieve lower sampling rates (i.e. 13.5MHz).  Page 11 of the Specifications document linked by Wallace provides more info on the signal requirements for providing your own external sample clock.