Looking for informations on signalID

[Alex-888888]

Dear Jan,

I'm still playing with my libreVNA and have fun ith it.
I have found one day a link to a website dealing with pikes generated due to the windowing and the reason oh signalID.
I don't find it anymore.
If you still have the link or anyone else thank you.
Have a nicce day,

Alexander

[jankae]

Hi Alexander, I am not sure which website you refer to. Most of the information about the LibreVNA can be found either here on Github or over in the support group: https://groups.io/g/LibreVNA-support/topics

The combination of spikes, windowing and signal ID does not ring a bell for me. These are three different things:

• Spikes: general term for any sharp peak in a measurement signal, either from the signal source or created by the instrument itself
• Windowing: window function applied to the raw ADC data prior to running the FFT. This function reduces spectral leakage and is necessary because the ADC does not necessarily capture an integer multiple of signal amplitudes. This is definitely needed in spectrum analyzer mode but can be skipped under certain conditions in VNA mode (because in a VNA you already know the precise frequency of the signal you are looking for)
• Signal ID: A special algorithm in the spectrum analyzer mode to reduce image signals. These image signals happen because the LibreVNA does not follow the "high first IF principle" of most spectrum analyzer designs (see https://rohde.nubicom.co.kr/wp/wp-content/uploads/2025/05/Spectrum_Analyzer_Fundamentals_eng.pdf, page 14)

[Alex-888888]

Dear Jan,

Thanks for your reply.
It helps.