HC - a very informative answer, thank you and I wasn't bored at all
The explanation of the required capture time for the planet gear signature was the bit I hadn't fully grasped - I suspect if I was to ask the question about our HUMS I might get the same answer from our engineers.
Our biggest problem with HUMS is sorting the wheat from the chaff when every sortie produces so many cautions and our F700s have lots of HUMS related defects (due to inaccurate HUMS accelerometers and the like) - it is easy to lose faith with what should be, and often is, a very powerful tool.