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      08-24-2008, 06:07 PM   #51

Drives: e46 M3
Join Date: Dec 2007
Location: Earth

iTrader: (0)

Originally Posted by swamp2 View Post
The accel is quoted as:
  • 0.5 mV/g nominal output (sensitivity)
  • bandwidth 0-1.5 kHz, 3% down on output at 500Hz, no specs given for higher frequencies
  • 0.3% non linearity
  • an odd accuracy spec., 0.3 mg/sqrt(Hz). ???.

You can get the entire spec sheet in my post #10.

The data sheet for the DAQ is attached. So many "accuracy" specs available it is tough to determine how much noise may be from the DAQ. Not my area of expertise. My gut tell me very, very little.

In general a car can slow down during a shift (well D3 yes, S4, no, if we believe this data!). My point was that the car can not be decelerating before any shift initiation (as the car was nearly pegged!). This makes the mounting and noise problems very obvious.

As well, as I mentioned previously, this accel was overloaded on input based on a typo on a supplied data sheet. I am going to get it repaired and recalibrated or replaced (on their dime!) soon, just to be sure.

Lastly a truly regulated DC power supply like this one. Might improve noise as well.

Any more donors??

I think the units for noise is an RMS value (sqrt(noise V^2 ~ 'power')), hence the sqrt of (hz)
mg = g x 10^-3
the sensor looks like it was designed for vibration/shock analysis
say the g force range is 1g
if the f of oscillation is say 1hz, noise is 0.3 mg
if the f is 400hz the noise is 0.3/20 mg 0.015 mg

this is a good primer

non-linearity is 0.3%, which is kinda like the accuracy or repeatability...

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