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Dual channel sampling

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Currently I am using a NI PXI-5122 card in a PXI-1000B chassis and I just set up the experiment to take data from both channels.  When I slowed down the pulse frequency I realized that the data isn't acquired simultaneously in the two channels.  Is it possible to do this?  I want to have simultaneous noise comparison so it's only somewhat useful in its current state.

 

Thanks,

 

Ben

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bump
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The card does do simultaneous sampling. How about attaching your code?
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Do I need to have two processors, or a hyper threading processor to do this?
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Solution
Accepted by topic author bbentelin

Why are you using two separate threads, one for each channel.  This could be why the readings do not coincide timewise.  In fact, with this method I would not expect them to.  Use one thread, combine the channels.  Each function that accepts a channel string, the input is labeled "channels", plural, more that one channel.  Set your channel string to "0,1".  Then both channels will be read at the same time and the output will be an array with element 0 being the cluster for the channel 0 and element 1 being the cluster for channel 1.  Use Index Array to separate them for processing.

 

- tbob

Inventor of the WORM Global
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Wonderful, thank you very much.
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Hello,

 

I have a question regarding the NI 5781.

 

With what accuracy are the two 100 MS/s, 14-bit, differential, DC-coupled inputs synchronized ? for example, if we measure two 1 [Mhz] sine waves with exactly the same phase at the ADC input, what phase noise (error?) should we expect ? (the sampling SCTL is driven by a 100 Mhz clock). 

 

Thanks!

 

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Hello,

 

I have a question regarding the NI 5781.

 

With what accuracy are the two 100 MS/s, 14-bit, differential, DC-coupled inputs synchronized ? for example, if we measure two 1 [Mhz] sine waves with exactly the same phase at the ADC input, what phase noise (error?) should we expect ? (the sampling SCTL is driven by a 100 Mhz clock). 

 

Thanks!

 

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Your question is completely unrelated to the topic in this 4-year old thread. Please start a new thread with your question.

 

Lynn

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