PSN-L Email List Message

Subject: Re: Integrating in WinQuake
From: "Geoffrey" gmvoeth@...........
Date: Sun, 22 Nov 2009 18:06:46 -0700

Velocity = FT/SEC
Seems to me like it may be simple to convert between these various forms
----- Original Message ----- 
Sent: Sunday, November 22, 2009 5:22 PM
Subject: Re: Integrating in WinQuake

> 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

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