There are many different ways that GPR users can “clean” up their data. One of the lesser known filters available is called the Deconvolution filter. This can be a powerful tool in helping remove noise, specifically “multiples” and “ringing” from your GPR data profiles.
Some of the sources of multiples and ringing include:
1) Metal – small metal objects will in a sense turn into an antenna when the electromagnetic wave passes through it. The metal then sends its own signal towards the GPR receiver creating a ringing in the data at that location. This however is not always the case, for example metal pipes usually don’t show ringing.
2) Non-metalic water pipes – This can be the case with other fluid filled pipes such as polylines filled with oil. The GPR wave will reflect of the front of the pipe, travel through the pipe, and reflect off the back end. This can create mirrored hyperbola. One on top of the other.
3)Trapped waves – This occurs when a wave is trapped in a small layer. The wave reflects off the bottom of the layer, then the top, then the bottom, then the top, etc…The reoccurance of reflections over and over produce a series of responses that all look similar but repeat through your profile from top to bottom.
4) Internal system noise – this can often be removed with a background filter (see https://www.youtube.com/watch?v=6W42EuiSgCY and https://www.youtube.com/watch?v=amYWV_M0oOI for more info on background filters), but if you want a more complex processing step then a deconvolution filter might be able to do the trick.
CAUTION: with the deconvolution filter you can remove noise, but you might remove important information from you data too. Use it wisely. I have not done a video on this until now because I usually focus on those filters that can be used on most projects. However, since a YouTube subscriber asked about it I made this video. This is a complicated high-order filter and should be used only when necessary.
Never forget, the purpose of data processing for GPR is to aid interpretation…NOT to create the prettiest picture.
I hope his was helpful and Good Luck!
If you use GPR and didn’t know how this worked, then you should get further training. Check out our upcoming webinars, classes, and live workshops at LearnGPR.com.
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