High-Speed Digitizers

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Set fixed sample rate for digitizer


I am using a NI PCI-5114 digitizer with NI scope SW.
I am configuring the sample rate with the niScope Configure Horizontal Timing. However the scope uses a sample rate a little higher than the specified sample rate.
I would like to sample exactly with 80MS/s.
Is there a way to force the scope to use a certain sample rate?



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Hello Gerald,
The PCI-5114 has a 250 MS/s internal clock.  To achieve lower sample rates, the digitizer decimates the incoming datastream.  Therefore, the only onboard sample rates you can achieve are integer divisors of 250 MS/s (125, 83.3, 62.5, etc...).
The only way to achieve the rate you are looking for is to use an external clock.  You can use either 80 MHz, or an integer multiple of 80 MHz then divide the clock down (160, 240).
I hope this helps.
Sean Close
Product Support Engineer: High Speed Digitizers
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