Re: motion detector

[Ludwik Kowalski <kowalskil@MAIL.MONTCLAIR.EDU>]

On Wednesday, October 1, 2003 Ludwik Kowalski wrote:

> Several weeks ago the issue of "noisiness" in the
> motion detector data was raised. This morning I
> conducted the following experiment. The Vernier
> detector was consecutively placed at several
> distances (between 0.73 m and 0.93 m) from a
> smooth board. The sampling rate was 10 per
> second for 10 seconds (meaning 100 separate
> measurements of the same distance).
>
> I wanted to see if all the 100 results were always
> identical. It turned out that for some distances they
> were and for others they were not. For example,
> d=0.933 m was the same 100 times but 0.952 was
> mixed with distances equal to 0.950, 0.951 and
> 0.953.  These differences are very small. I attribute
> such behavior to the step-wise nature of the ADC
> (analog to digital convertor). What else can it be?
> The "averaging" was set to "off" from the menu
> (instead of my usual 5 or 10).

Several weeks ago the issue of "noisiness" in the
motion detector data was raised. This morning I
conducted the following experiment. The Vernier
detector was consecutively placed at several
distances (between 0.73 m and 0.98 m) from a
smooth board. The sampling rate was 10 per
second for 10 seconds (meaning 100 separate
measurements of the same distance).

I wanted to see if all the 100 results were always
identical. It turned out that for some distances they
were and for others they were not. For example,
d=0.933 m was the same 100 times but 0.952 was
mixed with distances equal to 0.950, 0.951 and
0.953.  These differences are very small. I attribute
such behavior to the step-wise nature of the ADC
(analog to digital convertor). What else can it be?
The "averaging" was set to "off" from the menu
(instead of my usual 5 or 10).
Ludwik Kowalski