Hello and thank you for the post.
I have just seen that Phil has replied and some of the info mentioned is alos contained here but I will post either way as I have already typed this up.
You are most welcome to post anything here on the forum as this will allow everyone to see and share in the discussion.
You also have the firstname.lastname@example.org
support line for any concerns you have with the Pico products.
Your feedback, questions and queries are what drives the Pico products along and ultimately result in improvements with added features.
1. Only 50 seconds of data available?
This is the default recording time of the NVH software but can be extended to a maximum of 500 seconds:
Remember, whilst recording, you can press the space bar to pause recording if the vibration has cleared (or you need to stop the vehicle) and restart when relevant
2. Audio seems out of sync with the graphs?
Would it be possible to post your Pddata file here for review?
I can see that your second attachment displays the 3D graph with the microphone and you have highlighted data in your signal history between 240 and 242 seconds.
This selected data is then displayed in the 3D graph where it appears your highest audio level is indicated as a Tyre or Engine vibration order (Low frequency).
This level of vibration/sound would be better suited to the accelerometer, with a spectrum of 0-200 Hz.
This is not to say you cannot use the microphone because vibration and sound are one and the same. (Humans however feel vibrations from 0-20 Hz, not hear)
I would like to see the PDdata file where we could then reduce the size of your spectrum to enable better visibility /resolution of your peak audio amplitudes. I can then repost a screen shot that will help clarify the suggestion above. Please forgive me if I have misunderstood your question and this is not your concern, if you could feedback back on this issue that would be great.
3. Graphs don’t seem to be in sync with one another?
Looking at the graphs you have posted, one uses an accelerometer (0-200 Hz) and the other uses a microphone, (0-1700 Hz) both of which contain different data in the signal history, hence the data in the 3D display. Could you assist further here with your concern as these are different displays with different inputs and could not be in sync? (I hope I have understood your question)
4. SPL is off the scale?
In your second attachment your signal history is indeed over scale as the mic would appear to be located at the source of the noise, or in a noisy environment. To rescale, select “Engine Bay” at your set up screen as this will adjust your scale to allow for noise levels expected in the engine bay. The over range here may well effect the amplitudes we see displayed in the 3D frequency graph.
Could I ask if you were chasing a resonance type vibration/noise? The 3D display works very well in this scenario given resonance is present for a short time frame and using the 3D frequency display allows you to graph the build and decay of resonance as it appears.
If not, I would suggest the frequency display or the bar graph display to remove some of the additional information on display that is not relevant. (Easier on the eye)
I hope this information is of some help and please feedback when you can