Spikes in the plots by Scopy Network Analyser

[SteveNg2013]

Environment:

• OS: MacOS 13.5.2
• FW Version 0.32
• SW Version Scopy - v1.2.0 - e02cebe

Describe the bug
When running the Network Analyser I notice spikes on the magnitude and phase plots. This is similar to bug reported in 2017 (Spikes appear on the Network Analyzer plot #167) but using a very simple circuit.

To Reproduce

I wired up a simple bandstop filter with a 1k resistor in series with a DIY 288uH toroid inductor and a 0.1uF ceramic cap all in series and set the analyser to sweep from 10kHz to 100kHz and taking 100 samples. Amplitude was set to 10V.

Steps to reproduce the behavior:
Wire the filter.

1+, W1. 2+ 1-, 2-, GND
---------///------()()()------||------
1k. 288uH. 0.1uF

Expected behavior
I was expecting a smooth plot of magnitude and phase but get random spikes on both plots.

Screenshots
A screenshot is included

Additional context

The ini files might be useful to reproduce the error.
The ini file is located at: C:/Users/ali/AppData/Roaming/ADI/Scopy.ini
Please consider attaching it.

WHERE CAN I FIND THE INI FILE IN MACOS?

Add any other context about the problem here.
Screenshot 2024-02-22 at 4.56.46 pm.pdf

[adisuciu]

Is it possible to update to the latest Scopy v1.4.1 ?
If the bug still persists, you can use the network analyzer buffer previewer functionality that shows the time domain waveform for different samples when acquired.

[SteveNg2013]

I updated to 1.4.1 and still found the spikes. I am attaching a screen grab with the buffer preview. A look at the buffer at the point of the spikes shows nothing captured in the buffer. Is my interpretation correct? Question obviously is why the hiccup which occurs quite randomly?

Screenshot 2024-02-22 at 9.49.00 pm.pdf

[SteveNg2013]

Adrian,

Thanks for taking a look at the problem and your suggestion. I also wanted to add that I ran the same simulation in a Linux Mint 20 virtual machine on the same iMac and saw the same randomly occurring spikes.

[adisuciu]

There are 2 waveforms in the buffer.
The stimulus and the response.

There is no stimulus, and therefore there is no response ... the acquisition is correct though - you are seeing a (probably) floating signal around 0 volts

It almost looks like the circuit/connections have spurious failures - are you using a breadboard ? Can you confirm you are getting the same spikes when running the network analyzer in a loop (without a device under test) .. simply loop W1 to 1+ and W2 to 2+. You could also try different connection wires.

[SteveNg2013]

Thanks. I will do it tomorrow and let you know. Just in case you’re wondering, I’m in Sydney Australia.

…

On Thu, 22 Feb 2024 at 10:45 pm, Adrian Suciu ***@***.***> wrote: There are 2 waveforms in the buffer. The stimulus and the response. There is no stimulus, and therefore there is no response ... the acquisition is correct though - you are seeing a (probably) floating signal around 0 volts It almost looks like the circuit/connections have spurious failures - are you using a breadboard ? Can you confirm you are getting the same spikes when running the network analyzer in a loop (without a device under test) .. simply loop W1 to 1+ and W2 to 2+. You could also try different connection wires. — Reply to this email directly, view it on GitHub <#1551 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABH62A4TWBMGXH2D5ULDQMDYU4VVRAVCNFSM6AAAAABDUK7K3CVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSNJZGI4DCNZUGE> . You are receiving this because you authored the thread.Message ID: ***@***.***>

[SteveNg2013]

Adrian,I tried looping directly as you suggested, the same random spikes occurred. Yes, I am using a breadboard. I even changed breadboards but the same problem occurred. As for the wires, apart from the connectors that came with the ADALM2000 which I can’t do much about now, I’ve tried different wires and the problem did not go away. I wonder if there is a problem with either the ADC or the DAC in the ADALM2000.Thanks.Sent from my iPadOn 22 Feb 2024, at 10:45 pm, Adrian Suciu ***@***.***> wrote: There are 2 waveforms in the buffer. The stimulus and the response. There is no stimulus, and therefore there is no response ... the acquisition is correct though - you are seeing a (probably) floating signal around 0 volts It almost looks like the circuit/connections have spurious failures - are you using a breadboard ? Can you confirm you are getting the same spikes when running the network analyzer in a loop (without a device under test) .. simply loop W1 to 1+ and W2 to 2+. You could also try different connection wires. —Reply to this email directly, view it on GitHub, or unsubscribe.You are receiving this because you authored the thread.Message ID: ***@***.***>

[adisuciu]

We've tracked this down to the firmware version. Can you confirm that downgrading to firmware v0.31 fixes the problem ?

[SteveNg2013]

Hello Adrian, Thanks for tracking down the problem. I downgraded to v0.31 and can confirm that I have not seen any spikes in the traces. Thanks again.

…

On 27 Feb 2024, at 10:34 pm, Adrian Suciu ***@***.***> wrote: We've tracked this down to the firmware version. Can you confirm that downgrading to firmware v0.31 fixes the problem ? — Reply to this email directly, view it on GitHub <#1551 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ABH62AZ4JEPYTQNXEUAMHATYVXAEZAVCNFSM6AAAAABDUK7K3CVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTSNRWGM2TEMRTG4>. You are receiving this because you authored the thread.

[adisuciu]

Thanks, we're looking into a fix in the firmware ..