Re: Video capture errors (Was "DATA on collapsing WTC/more")

[brian whatcott <inet@INTELLISYS.NET>]

At 12:36 9/22/01 -0700, Glenn wrote:
> ...  I also plotted the residuals (A*t^n-yactual) and saw
> the same thing.  I haven't done a detailed analysis, but the amplitude,
> period, and phase lag described by Brian is unmistakable.  (Brian, can you
> confirm that the amplitude is 3.9 *feet*?  I converted all my calculations
> to SI units, and the amplitude looks like 4 meters to me.)

I used 'amplitude' in the sense of the coefficient h of the expression
 h*sin(2*pi*t/3 + pi) with which I approximated the residuals.
This is intended to reduce, and normally distribute the errors about the
estimate. The residual can be further refined with a second harmonic
of 1.5 seconds period at reduced amplitude.
I used only the first and last columns of your data which begin like this:
t (sec)         y (ft)
0           0
0.0336     -2.260869565
0.0671     -2.260869565
0.1007      2.260869565
0.1343      0
0.1679      2.260869565
0.2014      0
0.235       2.260869565
0.2686      0
0.3021      2.260869565
0.3357     -2.260869565
0.3693     -2.260869565
0.4029      0

(See how the displacement is symetrically distributed around
the time mark of 0.2014 ??)




brian whatcott <inet@intellisys.net>  Altus OK
                Eureka!