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 ChapmanIn 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