In the A/D world, there is something called the Nyquist criteria - you need to sample at least 2x the highest frequency you expect to see, to be able to accurately 'see' the analog signal from the digital data.
Therefore, it's smart to use a lowpass filter with an edge at 1/2 your sampling frequency, which I'm sure we don't have. Any frequency components above this value will completely mess up the A/D, rendering the data useless *except* the A/D shouldn't cause the max or min amplitude to exceed the real analog values. Because of this, and I can't see a way to get -5G's due to drag, I suspect some resonance in the accelerometer itself occurred, or a resonance in the board holding the accelerometer. One board design I am contemplating is a small 3-D cube holding 1,2 or 4 rate gyro's in the pitch and yaw axis (tradeoff cost .vs. accuracy) and 1 or 2 rate gyro's in the spin axis, plus 1 or 2 accelerometers for the z-axis. Dan In a message dated 11/18/2 1:37:29 AM, [EMAIL PROTECTED] writes: << I like this one even less, b/c it is my understanding that spurious results from undersampling appear only if you interpolate the data or run it through a fourier transform. Dave W -- am I wrong about that? >> _______________________________________________ ERPS-list mailing list [EMAIL PROTECTED] http://lists.erps.org/mailman/listinfo/erps-list
