Software fft or hardware fft

[alex.]

I am trying to use DAQ5133 to collect waveforms. Then do fft(soft) with the waveform and further analysis.

I display the waveforms and analysis results together, and found the analysis results lag quite a lot.

Then I found 5133 seems can do fft in NI scope front panel with spectrum.

If it is true, can I use the hardware fft to make it faster and how to make it? Thanks.

[Meadow · Accepted solution]

Hello Turbot,

The NI Scope Soft Front Panel can do FFT under the measurement options. The measurement is a postprocessing analysis in the Scope soft front panel software.

So with 5133, there is no hardware FFT that you can use to make a faster fft.

What kind of fast that you are trying to achieve by doing hardware FFT? Do you need a faster bandwidth or else?

Regards 

[alex.]

 The sampling rate is 100M, and every time I will collect 512 point and do fft, then do further data processing.

 The trigger is random. There may over 1000 times of triggers in one second.

[johnsold]

turbot,

Try  using two loops, one for data acquisition only and another for processing and display.  Pass the data from the DAQ loop to the processing loop via a queue.  The two loops can run at very different speeds.  The only real constraint is that the processing loop on average must keep up with the DAQ loop to prevent using up all available memory.  If the program needs to run for a long enough duration that memory becomes a problem, be sure to minimize the number of copies of the data.

Lynn