PSN-L Email List Message

Subject: Re: Integrating in WinQuake
From: ChrisAtUpw@.......
Date: Sun, 22 Nov 2009 19:22:18 EST


In a message dated 22/11/2009, rsparks@.......... writes:

For some  reason, I got to thinking about the difference between 
acceleration and  velocity detectors today, maybe prompted by your 
comment (a few days ago)  about using WinQuake to double integrate the 
data to convert acceleration  data to displacement data.  The problem is 
that WinQuake (so far as I  can determine) does not allow double 
integration of the data.  Only  one integration operation is allowed.
Hi Roger,
 
    Have you checked Prof Wielandt's graphs of the  various output systems 
on psn?

Why does this matter?  Until today, I had  concluded that my 
magnet-coil detection system was a velocity system that  only needs one 
integration to convert to displacement.  But today I  thought about what 
happens if my seismometer (a vertical) was placed on a  rocket that 
boosted to a steady velocity.  My seismometer would only  detect the 
acceleration, not the steady state velocity.  Hence, my  detector must be 
an acceleration device.  Thus I have a logical  reason to do the second 
integration of data. 


Are you confusing detectors which have 'DC' as well  as 'AC' sensitivity, 
with 'AC' only detectors?
 
    Your mass tries to stay stationary. If you give the  frame a small 
velocity, the coil moves in the magnetic field giving an output  proportional to 
that velocity.
 
    Regards,
 
    Chris Chapman





In a message dated 22/11/2009, rsparks@.......... writes:
For some=20 reason, I got to thinking about the difference between
acceleration= and=20 velocity detectors today, maybe prompted by your
comment (a few days= ago)=20 about using WinQuake to double integrate the
data to convert acceler= ation=20 data to displacement data.  The problem is
that WinQuake (so fa= r as I=20 can determine) does not allow double
integration of the data. = Only=20 one integration operation is allowed.
Hi Roger,
 
    Have you checked Prof Wielandt's graphs of th= e=20 various output systems on psn?
    Why does this matter?  Until today,= I had=20 concluded that my
magnet-coil detection system was a velocity system= that=20 only needs one
integration to convert to displacement.  But tod= ay I=20 thought about what
happens if my seismometer (a vertical) was placed= on a=20 rocket that
boosted to a steady velocity.  My seismometer would= only=20 detect the
acceleration, not the steady state velocity.  Hence,= my=20 detector must be
an acceleration device.  Thus I have a logical= =20 reason to do the second
integration of data.
    Are you confusing detectors which have 'DC'= as well=20 as 'AC' sensitivity, with 'AC' only detectors?
 
    Your mass tries to stay stationary. If you gi= ve the=20 frame a small velocity, the coil moves in the magnetic field giving an out= put=20 proportional to that velocity.
 
    Regards,
 
    Chris Chapman

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