I happen to live in a very noisy area and one no closer than 300 km from the nearest earthquakes, 2.5 magnitude at that. Teleseisms is what I am looking for. Is there any way to filter the data before it goes to the helicorder? Years ago I recall being able to do that with PSNs software. I should add that I am not a programmer type!
What you’re asking for is called “denoising”.
There are numerous ways to do it (ask Google), but they rely on you being able to separate the noise from the data you’re interested in. If the noise is at a constant level, this is relatively easy (using orthogonal wavelet decomposition), but if you signal looks like mine:
Where the noise varies in level depending on whether the traffic is light or heavy and there is the odd train as well. All this noise occurring over a wide frequency spectrum, just like an EQ.
Extracting weak EQ signals from such data is difficult, if not impossible. How can the algorithm determine what is noise and what is EQ?
In my case, I’m not too worried because I live in an active EQ environment, and when we get an EQ nearby above magnitude 3, it swamps the noise.
In your case, I don’t know if it will be possible to see teleseisms.
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In Swarm it is not possible for filter the entire helicorder (or the data before it arrives at Swarm).
New developments on that front will be coming out later this year. So stay tuned and have fun Shaking!
Branden
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