PSN-L Email List Message

Subject: Re: Earthquake monitoring in Iceland/Scotland/ and the US From: "jimo17@......... jimo17@juno.com
Date: Wed, 28 Dec 2005 14:04:57 GMT


Hi Chris- Thanks for the comment on Robert's Circuit- Equalizer Board as=
 I have used Mauro's commercial version (SEQUA10 ) and found it to be qu=
ite good.
Question- =

Do you believe a digital inverse filter would work just as good?
BTW_ I enjoy reading all your comments...Thanks....Jim

                  Jim O'Donnell     =

         Geological/Geophysical Consultant
            GEOTECHNICAL APPLICATIONS
702.293.5664	    geophysics@..........
702.281.9081 cell           jim@..........
>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
-- ChrisAtUpw@....... wrote:
Hi Ian,
    If you are using one of Larry's L15B units, you should be able to se=
al it with the "non acetic acid" type of silicone rubber sealant OK. Thi=
s should be good from -40 C to 70 C. The Geospace geophones seem mostly =
rated from -45 C to 100 C, but I am not sure about the plastic case for =
the higher temperature. An alternative sealant which I use is Blue-Tack =
/ White-Tack from a stationery supplier. It is a putty like, non hardeni=
ng adhesive sold for attaching posters etc to walls without damaging or =
staining the surface finish. It is not available in the USA.
     I agree about the environmental noise, but you could get more wind =
noise in an outside location. This is likely in Iceland.     I use a SEQ=
UA10 frequency extension board from http://www.sara.pg.it/prod04_04_e.ht=
mThey cost E30 and extend the low frequency response of a 4.5 Hz geophon=
e down to 1/10 the natural frequency, a bit like the low frequency boost=
 circuit on a HiFi amplifier. This enables you to sense both P and S wav=
es, at 1.0 and 0.5 Hz, for local, regional and teleseismic events with a=
 4.5 Hz geophone. It is a modified version of the Roberts' circuit.     =

Hi Chris- Thanks for the comment on Robert's Circuit- Equalizer= Board as I have used Mauro's commercial version (SEQUA10 ) and fou= nd it to be quite good.

Question-
Do you believe a digital inverse filter would work= just as good?
BTW_ I enjoy reading all your comments...Thanks....Jim=

           &nb= sp;      Jim O'Donnell     =
         Geological/Geophysi= cal Consultant
         =    GEOTECHNICAL APPLICATIONS
702.293.5664    = ; geophysics@..........
702.281.9081 cell        &n= bsp; 
jim@..........
>&= gt;>>>>>>>>>>>>>>>>>&= gt;>>>>>>>>>>>>>>>>>&= gt;>>>>>>>>>>>>>>>>>&= gt;>>>
-- ChrisAtUpw@....... wrote:
Hi Ian,
 &nb= sp;  If you are using one of Larry's L15B units, you should be= able to seal it with the "non acetic acid" type of silicone rubber seal= ant OK. This should be good from -40 C to 70 C. The Geospace geophones s= eem mostly rated from -45 C to 100 C, but I am not sure about the p= lastic case for the higher temperature. An alternative sealant which = I use is Blue-Tack / White-Tack from a stationery supplier. It is a = putty like, non hardening adhesive sold for attaching posters etc t= o walls without damaging or staining the surface finish. It is not avail= able in the USA.

 
    I agree about the environmental noise, but = you could get more wind noise in an outside location. This is likely in = Iceland.
 
    I use a SEQUA10 frequency extension board f= rom http://www.sara.pg= ..it/prod04_04_e.htm
They cost E30 and extend the low frequency response of a 4.5 Hz&nbs= p;geophone down to 1/10 the natural frequency, a bit like the low f= requency boost circuit on a HiFi amplifier. This enables you to sense bo= th P and S waves, at 1.0 and 0.5 Hz, for local, regional and teleseismic= events with a 4.5 Hz geophone. It is a modified version of the Roberts'= circuit.
 
    Regards,
 
    Chris Chapman

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