PCI 5124

[Kelkar]

Sir,

I am using PCI 5124 card to digitize 3us half sine pulse of amplitude 5V, with a PRR of 1Hz.

The level is kept at 3V and leading edge trigged configuration. 

I saved the waveform in excel format at two differnt times. i found that the absolute time at the start of the wavefrom is diffent for different saved waveforms(it is varying also and it of the order of 4ns).

I am  interested  in comparing the two saved saveforms in time domain at every data points.

Regards

kelkar 

[alipio]

Hello.

This is a good signal for multirecord adquisition. There are some examples in your Labview examples/instr/niscope  folder.

Also, activate TDC option for a very good time.

If you want to compare two different adquisitions, you will have to correct absolute time to simulate simultaneous adquisitions.

Best regards.

Alipio.

[DFGray]

The triggering circuit of the 5124 gives subsample accuracy for most scan rates.  Since the trigger position is essentially random in time relative to the scan clock, multiple data acquisitions will give you small variations in start time.  These variations should all be under a sample period.

If you need to mathematically compare several waveforms and the jitter is too large, you have several options:

1. Take multiple waveforms until you get several that have similar start times
2. Resample the waveforms using the LabVIEW resampling VIs (e.g. Align and Resample or Resample).
3. Roll your own resample algorithm.  Fourier techniques work well for subsample time shifting.

Let us know if you need more information.