LabView Scope delta measurement between signals

[NedyalkoPeshev]

Hi all! I am looking forward to solution how to visualist and measure delta between 2 input square signals. Can you support me with ideas?

Signals going out from PXI card and return again inside to other input pin from external board. The main case is to find a way to visualist signals and measuring delta between them. Thanks, in advanced for your feedback.

[GerdW]

Hi Only4,

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@NedyalkoPeshev wrote:

Hi all! I am looking forward to solution how to visualist and measure delta between 2 input square signals. Can you support me with ideas?

Signals going out from PXI card and return again inside to other input pin from external board. The main case is to find a way to visualist signals and measuring delta between them.

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• Which "PXI card" are we talking about?
• Which "delta" do you want to measure? (amplitudes, phase shift, duty cycles, …)
• What have you tried so far, where are you stuck?

[NedyalkoPeshev]

Delta between phase shift between 2 square signals. I don't have a card. Need just conception, because I need to select card for purpose. Thats what I am try. First to have 2 signals with fixed phase delta. I am looking for mathematics model for calculate delta. The real delta between signals will be around 5ns - it's important for card selection.

[Henrik_Volkers]

capture both channels and

if arbitary signal

-use crosscorrelation

if stable periodic 

-use FFT and use the phase differences of all signal bins 

 (best if the signal generator clock is locked to the DAQ clock and rec window on full periodes)

5ns is the delay of a little more than 1m RG58 cable .. 🙂 

You will need to measure the inter channel delay of your scope card and every involved element.  

a good wideband power splitter (I used a DC-8GHz resistive one) two cables ,

measurements with swapped cables,channels, PS outputs, mark every cable and connector 😉

[NedyalkoPeshev]

Now its thrown a lot of result (5 values per 5s). I keep values in array and compare with 5nS. Differently not pure but i'm think on the right way. Just now its simulation. I need to connect on real card and try with real signals. Can you check my decision. Best regards.

[Henrik_Volkers]

A delay for two signals of same frequency is a phase shift.

Why do you compare two signals of different frequency?

[NedyalkoPeshev]

You are right. I need a way to attest phase shift. Do you know way of some tutorial to do that?

[NedyalkoPeshev]

Can you give me a way for this solution "A delay for two signals of same frequency is a phase shift". I need a way to measure phase shift between signals with same frequency. Thanks in advanced for support.

[Henrik_Volkers]

Have a look at  the Extract Tone Information.vi  (Signal processing/measure) .. (and Help file 😉 )

apply it on both signals should give the same freq. ... and calc the difference of the phases...

[NedyalkoPeshev]

Card is PXI 6341 with 100MHZ internal clock - like specification. I hope to catch 10nS difference between delay of signals. That is a main reason of experiment. Currentlly, I have an error. Physical ports are PFI 8 and PFI 9 - part of mode in counter ctr0 in card 6341. Definitely I have problem with counter configuration I think. 

error from program is Possible reason(s):

Requested values of the Minimum and Maximum properties for the counter channel are not supported for the given type of device.
The values that can be specified for Minimum and Maximum depend on the counter timebase rate.

Property: CI.Min
Corresponding Value: 20.0e-9
Property: CI.Max
Corresponding Value: 42.949673
Property: CI.TwoEdgeSep.Units
Corresponding Value: Seconds
Option: 1
Property: CI.CtrTimebaseRate
Corresponding Value: 100.0e6
Property: CI.Min
Value Must Be Greater Than: 20.0e-9
Property: CI.Max
Value Must Be Less Than: 42.949673