Hello and thank you both for the posts.
To answer your questions surrounding suspension knocks, rattles and creaks etc.
I would be very careful about sporadic noise location and detection using a single accelerometer/ microphone as I have had mixed success locating particular noises that are very infrequent or of low sound level.
From experience I have found multiple microphones placed about the area of concern have helped to locate the source. I refer here to “Chassis Ear” or a similar device in these scenarios.
For example, looking for a single “Knock” sound over uneven road would most certainly be detected by the accelerometer but due to the infrequent nature, this would not be transferred to the frequency display. (We need vibrations/noise present for around 3 seconds)
This is an area under review here at Pico and I have no doubt we will produce a solution at some point in time where these noises will be detected using multiple “clip on devices”
Moving onto the NVH kit accelerometer sensitivity and axis measurement, the accelerometer included in the NVH kit is in fact a 3 axis device capable of measuring vibration in 3 directions X, Y, and Z or to put this another way, X axis vibration Fore/Aft, Y axis vibration Vertical, and Z axis vibration Lateral.
However all three axis are summed together inside the NVH interface box in such way as to give the end user an overview of all axis. Here then there is no rejection of a particular vibration in a specific axis/direction, everything is accounted for.
The real beauty of such a feature is that with one scope channel, the end user will pick up a vibration present even when the direction of vibration is unknown.
For example, mounting the accelerometer vertically on a chassis member will detect all vibrations in all axis/directions, as will mounting the accelerometer horizontally on the same chassis member.
What you may experience is a reduction or an increase in the amplitude of a particular vibration, but the frequency will remain the same and this is what we need to identify. (The frequency of a vibration)
I agree with all you are saying Stuart regarding “multiple measurements” to attempt to identify the direction of a vibration and we are working towards a solution where all 3 axis can be measured and displayed individually.
I hope some of this helps, take care…….Steve