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I'm measuring the group delay of some 60in cables with a NanoVNAH4 and I am getting outliers in the data. I am using nano-vna saver and I have tried both with on board calibration disabled and calibrated from 50kHz to 1.5GHz, the outliers are present still. I also have another H4 and I had the same issue just at a lower frequency ~150MHz. In the attached plot the points go to about +- 20 ns at just under 700MHz. I have also changed the sweep to have a lower df width but the same outliers were there at the same frequency. My sweep here is 1Mhz to 701Mhz 1212 pts 3avg df=578kHz

Is there any explanation or way to minimize this? Or is the best path forward just to remove the outliers manually when processing the data.

Thanks!

Or is the best path forward just to
remove the outliers manually when processing the data.

can you send as attachment your .s2p file

I wrote a little software to smooth out the errors. I would see what happens.
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F1AMM
Fran?ois

De la part de astech119
Envoyé : lundi 26 juin 2023 18:32

Here it is, thanks for taking a minute to look into it.

Here it is, thanks for taking a minute to look into it.

Attachments :
- your smoothed file
- the processing log (.CSV) showing the anomalies detected.
- the S21 Group Delay (ns) on the smoothed file
73
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F1AMM
Fran?ois

De la part de astech119
Envoyé : lundi 26 juin 2023 20:24

Thanks Fran?ois for the response and taking the time. I wanted to put another plot on here, this is with another NanoVNAH4 I have and the outlier is in the middle of the sweep at ~130MHz. The calibration of the device does not get rid of it. I would like to know if there is a way to remove it experimentally or if anyone knows what the cause is.

Can you measure just the area where the spike is. I have had odd readings when the scale has been too coarse, and have missed some retails..