Re: Air resistance

[John Gastineau <gastineau@mindspring.com>]

At 10:24 AM 12/15/97 -0800, John Mallinckrodt wrote:

> I hadn't previously understood that the d values *themselves* were subject
> to smoothing.  Is that really true?  

No, it's not true. The distance values are nearly raw data. Nearly, in that
the computer has merely calculated a distance from the round trip echo time
using the speed of sound at the specified air temperature.

The velocity and acceleration data are, clearly, processed from the distance
data. The derivative calculation is a running linear least squares fit to
the specified number of points. The velocity data are thus "smoothed"
(that's not really the right word) in that they are dependent on a range of
distance measurements (3, 5, 7, ...) rather than just on two adjacent
distance measurements. 

JEG


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John E. Gastineau      gastineau@mindspring.com               KC8IEW
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