Is this real knock?

[Manuel]

Hello.

I have been testing and tuning for the past 6 months, car is an Australian HSV VZ Clubsport, engine is LS2 with E40 pcm.

I have noticed some knock occurring in my log, it starts at frame 1974. knock peaks at 5.7 and then ramps down to 0. No audible knock was detected.

So is this real knock?

How can I better understand what is happening?

Thanks.

Manuel