lowest frequency with 5431

[Kallis]

What will be the lowest frequency that can be generated with NI 5431 AWG.? I have a requirement for generating .001Hz is it possible? What is the frequency resolution of the card.? The spec tells that in 'High resolution" its 1.08uHz. But what exactly is this "High resolution"? Any help will be highly appreciated.

TIA

Kallis

[kalyanramuv]

Hi Kallis,

There are two things here:

5431 can operate in DDS Mode and ARB Mode:

In DDS mode, the frequency resolution is ~9.3mHz. This means that you can generate standard signals such as square,sine etc., with a resolution of ~9.31mHz. In other words, you can generate the standard signals with frequencies which are multiples of ~9.3mHz. This mode is similar to standard function generator.

In ARB mode: you can download waveforms into ARB memory, loop them and link different waveforms. You can even generate non-standard waveforms in ARB mode. For this waveform generation, a update clock is needed. This update clock mode can be divide-down or high-resolution. High resolution in this context refers to the high resolution of update clock itself (not the frequency of the waveform). The resolution of clock used for ARB mode, depends whether update clock mode is high resolution or divide down. The "high resolution" spec refers to resolution of clock in this mode.

Refer to "Internal Sample Clock Sources" section in NI signal Generators help for more information on high-resolution clocking.

Coming back to generation of 0.001Hz signal, you can generate the signal in DDS Mode if it is standard signal such as square,sine.If the signal type is not supported in DDS Mode of the card, you can generate using ARB mode. You can generate the waveform using functions in LabVIEW or you can use arrays to define custom waveform in LabVIEW.

Please let me know if this answers your question.

Kalyan

[Kallis]

Thank You, Kalyanramu.

[psisterhen]

Since the frequency resolution of the output waveform in DDS mode is ~9.31 mHz, you will not be able to use DDS mode to generate the signal you want at .001 Hz.  (Because the lowest frequency signal you can generate is 0 Hz, and the next highest would be .00931 Hz).

Don't worry, though- you will be able to generate the signal in ARB mode (which means the Outmode Mode attribute will be set to Arbitrary Waveform or Arbitrary Sequence).  You simply have to create your own waveform and set the sample rate appropriately.

[kalyanramuv]

Hi

Thanks for the correction. You will not be able to 0.001Hz as it is less than 0.0093Hz (9.31mHz). As I said in my post, you will able to do only integer multiples of 9.31mHz. I didn't convert the numbers properly. Thank you very much psisterhen