Hello all,
I'm operating in the highly ablative regime and I generate the usual waves (skimming, rayleigh, 2L, 2S etc) as well as a large and wide shock wave of some variety. I've tried high, low and bandpass filters, but these seem to either have little effect, or also remove the defect response. You can see examples here https://www.dropbox.com/s/7nxowulxnb4uatv/ascans.jpg?dl=0 the left most image is the raw A-scan (looking at displacement, it's been passed through a differentiator), the middle is after a 4MHz high-pass and the right most image is a 3MHz high pass.The right most signal is the one which is causing me issues.
I hope this algorithm could help you. It can be used in time based or after making FFT in the frequency based. It is very accurate.
Data Algorithm XDX11. An improved high speed algorithm for image ...
Sorry but I don't see what is your issue. I cannot see a 'base line shift'... Please clarify.
I guess 'baseline shift' isn't the right term, I have a very broad in time and large in amplitude signal in my data, it's the furthest right signal in the data I've posted. It's a parasitic signal which is causing me to loose information in certain configurations. I think it might be an audible soundwave.
Ben, how thick is your sample and what material is it made from?
Hi William, sorry for the delay, the sample is 25mm thick Aluminium plate. I've come to the conclusion that this problematic wave is an audible acoustic shockwave due to the highly ablative regime that I'm operating in. I've yet to find a way to filter it out using signal processing, but there are a few modifications to my experiment I shall try to see if that helps. Thank you all for your comments, if anyone in the future has a similar issue, please feel free to contact me and we can discuss.
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