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Active Message Threads for May 2007
John or Jan Lahr
Hi Chris,
Good questions.
For the helicorder view AmaSeis only allows one filter to filter out
high frequencies and one to filter out low frequencies.
For example, if you want to enhance the high frequency signals from
local events on your helicorder record, you might filter out
frequencies below 1.5 Hz, which leaves frequencies between 1.5 Hz and
3 Hz. (Note that because we are only sampling at 6 Hz, the highest
frequency that can be resolved is 3 Hz.) The bottom of the
helicorder re…
[more]
Replies
-
RE: Another example of filtering - Chris Midden - 2007-05-03 22:33:57
A while back I showed how to set up a helicorder filter in AmaSeis so
that the surface waves from distant earthquakes would be enhanced.
(See: http://jclahr.com/science/psn/as1/filtering/index.html)
The other day I received an earthquake notification message* from the
USGS about a 3.1 earthquake not too far from my station in Corvallis,
Oregon. Although I couldn't see anything on my helicorder record,
especially with the filter I was using to enhance low frequencies, by
switching to a f…
[more]
Replies
-
RE: Another example of filtering - Chris Midden - 2007-05-03 15:37:20
