The other day, a client asked us about the duration of the wave in PET.
The ASTM D5882-16 Standard for pile integrity test has a requirement about the duration of the wave: “Adjust the apparatus to reproduce a signal having a duration greater than 2L/c plus 5 milliseconds, where L is the pile length, and c is the material wave speed.”
Where can we see this in the PET software?
PET software never asks the user to do complicated calculations.
When you start the test (Pressing [start]), the maximal capture time is set to 6L/C
In this case, L = depth scale
(Approximately scale X 3)
This is always much more than 2L/C+5]mSec that the standard requires - so you should always be OK.
For example, if you set the planned length (the red triangle) and scale to 10m (With C=4000m/s), the standard requires 10mSec (5+2L/C = 5mSec+2*10/4000 = 10mSec), and PET will use 15mSec (6L/C = 50/4000) - more than the standard requires (Standard +)
To see this in the software, drag the end-of-line mark (the red square) to the maximum right. This is the maximal captured length L. To convert this length to time, use 2L/C
For example, if you start a test with a planned length of 10m and scale of 12m (C=4000), you will be able to see up to 36m = 18 mSec. The standard requires 5+2*10/4000 = 10mSec
Note: PET also adds some time BEFORE the trigger. This pre-trigger information is also more (Standard +) than the standard. Allows you to see the full impact trigger
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