Hi

I will try to get a bubble level tomorrow. I can't get it at this hour.
With the current setup I can get a good signal at 15 seconds with the
software filtering, the main signal is at 0.1Hz (5 seconds). What can I
expect to detect at that period with my lehman seismomter ?

Here are pictures of the final setup. I have made some changes since I
last put pictures on the web.

http://www.jonfr.com/myndir/v/geology/lehman/p5100001.jpg.html (First
picture)

Regards.
J=F3n Fr=EDmann.

On lau, 2009-05-09 at 17:36 -0700, shammon1@............. wrote:
> Try using a bubble level to know when the boom is level. Then tilt the en=
d of the boom down, never up. I normally start by using a level to make sur=
e the vertical upright is at zero degrees and then I level the boom. I then=
 add about 1-5 degree of tile in the  upper most point of the upright in th=
e direction of the boom. I have three level screws the base plate and a mac=
hine screw in the end of the boom to make the adjustment.=20
> Regards, Stve Hammond PSN San Jose Aptos, CA
>=20
> -----Original Message-----
> >From: J=F3n Fr=EDmann 
> >Sent: May 9, 2009 4:28 PM
> >To: psn-l@..............
> >Subject: Re: Incresing the period of a lehmans seismomter ?
> >
> >Hi all
> >
> >Thanks for the help of the weeks. I could not have fixed the issues with
> >out you all.
> >
> >I am still having minor issues adjusting the period of my lehman sensor.
> >I am not sure if I have to move the boom up or down to increase the
> >period of my sensor.
> >
> >Regards.
> >J=F3n Fr=EDmann.
> >
> >On f=F6s, 2009-05-08 at 05:41 +0000, JAMES RIDOUT wrote:
> >> Jon,
> >>       I found it very confusing when setting the period for my
> >> seismograph, and for a=20
> >> long time took the period to be the time it takes the arm to swing
> >> from one side to the
> >> other.( I could never get much more than 10 seconds)!!.
> >>  But apparently I am wrong, The period is the time it takes for the
> >> arm to swing
> >> past the same point in the same direction twice. So if you hold the
> >> arm towards you
> >>  and let it go, as it passes the centre, start a stopwatch, then
> >> let the arm go to the other side,
> >> then back towards you , and as it passes the centre again press stop.
> >> This is the period.
> >>   Anyone please correct me if I am wrong. !!.
> >>                                                                 James
> >>=20
> >> --- On Fri, 8/5/09, J=F3n Fr=EDmann  wrote:
> >>=20
> >>         From: J=F3n Fr=EDmann 
> >>         Subject: Re: Incresing the period of a lehmans seismomter ?
> >>         To: psn-l@..............
> >>         Date: Friday, 8 May, 2009, 2:08 AM
> >>        =20
> >>         Hi all
> >>        =20
> >>         I got the period down to 6 seconds at the lower end, but at 4 =
seconds
> >>         the high end. But I have to do it adjust the period really slo=
wly. I am
> >>         not sure what I can detect at 6 seconds.
> >>        =20
> >>         Geoffrey, I know what you mean. I am trying to understand some=
thing in a
> >>         diffrent language and am trying to understand something that I=
 have not
> >>         got a big traning on.
> >>        =20
> >>         Regards.
> >>         J=F3n Fr=EDmann.
> >>        =20
> >>         On fim, 2009-05-07 at 17:04 -0700, Geoffrey wrote:
> >>         > Gee, I believe this to be one of those
> >>         > garden gate seismometers.
> >>         > I always thought of it as a modified
> >>         > pendulum changing the acceleration of gravity
> >>         > in a trigonometric fashion.
> >>         > This means the mass is the lowest point on the lever arm
> >>         > or you can not have stability.
> >>         > It manipulates the pull of gravity
> >>         > like Sine or Cosine of the angle relative
> >>         > to horizontal.
> >>         > I believe you guys are thinking much more
> >>         > complex then myself.
> >>         > You more than likely will never
> >>         > take souls like me very serious.
> >>         > Sort of like Rodney Dangerfield ???
> >>         >=20
> >>         > ----- Original Message -----=20
> >>         > From: "J=F3n Fr=EDmann" 
> >>         > To: "PSN-Postlist" 
> >>         > Sent: Wednesday, May 06, 2009 7:54 PM
> >>         > Subject: Incresing the period of a lehmans seismomter ?
> >>         >=20
> >>         >=20
> >>         > Hi all
> >>         >=20
> >>         > Tomorrow I am going to make the final changes to my lehman s=
eismomter. I
> >>         > hope that this changes make the seismomter get down to 20 se=
conds period
> >>         > at most.
> >>         >=20
> >>         > The only thing that I need to know is this. What is the best=
 way to
> >>         > increase the period of my lehman seismomter ? Moving the boo=
m down or
> >>         > up ? Or do I have to do something else.
> >>         >=20
> >>         > Regards.
> >>        =20
> >>         __________________________________________________________
> >>        =20
> >>         Public Seismic Network Mailing List (PSN-L)
> >>        =20
> >>         To leave this list email PSN-L-REQUEST@.............. with
> >>         the body of the message (first line only): unsubscribe
> >>         See http://www.seismicnet.com/maillist.html for more informati=
on.
> >
> >
> >__________________________________________________________
> >
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> >
> >To leave this list email PSN-L-REQUEST@.............. with
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>=20
> __________________________________________________________
>=20
> Public Seismic Network Mailing List (PSN-L)
>=20
> To leave this list email PSN-L-REQUEST@.............. with=20
> the body of the message (first line only): unsubscribe
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