PSN-L Email List Message
Subject: Re: digital filtering
From: Mark Robinson mark.robinson@...............
Date: Fri, 03 Feb 2006 11:48:19 +1300
Jón Frímann wrote:
> I have set the raw data on digital filtering, but that one is on 5.5Hz
> but the online graphs are now on 4Hz. It appears that the noise is
> somewhat above 10Hz (there is noise on 10Hz, but alot less then if i
> record from 2Hz to 60Hz), maybe above 6Hz. I just haven tested it
> properly yet. I do not know how this filtering will effect my abliti to
> detect earthquakes. But i hope that the won't be any effect of this in
> regarding detecing earthquakes.
The more you filter the higher frequencies out the less small local events you
If you look at http://www.geonet.org.nz/drums/snzo-drum.gif and
http://aslwww.cr.usgs.gov/Seismic_Data/telemetry_data/SNZO_24hr.gif you will
see that the first one shows local events while the second shows teleseisms.
Both traces come from the same sensor, the Geonet display showing the data with
all the long period stuff filtered out and the usgs one showing the same data
with all the high frequencies filtered out.
Public Seismic Network Mailing List (PSN-L)
[ Top ]
[ Back ]
[ Home Page ]