5G system-level simulation showing unwanted signal in spectram analyzer

File attached.

I'm using Matlab's 5G toolbox to do a system level simulation (with the attached code). The code runs fine. To generate traffic, I am using OnOffTraffic generator function. I am producing only downlink traffic (gNB to UE).

As I understand, the system level simulation does not transmit SSB (signaling). Only data is being transmitted. But if I plot a spectrogram of the received samples (from signal analyzer app), I am seeing power at certain intervals (has pattern). These are surely not data traffic as I have confirmed by varying data rates and on-off timing.

Can anyone give me any idea on what these narrow signals are ? How are they even there ? Or how to know where they are generated from ?

Thank you,

Sam

[Saurav]

Can you provide the snapshot of what you are getting in the Signal analyzer app, and what exactly are you plotting?would be helpful in debugging.