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What does the data collection time have to do with the data collection rate?
Or did you modify your program to collect a fixed number of points during a
variable data collection time?
My experience with the motion detector is that they just don't give very
reliable results when run much faster than 60Hz, and some cranky units don't
like running even that fast. If you're really trying to run the detector at
rates over 100Hz, notice also that you're severely limited in range due to
the relatively slow speed of sound. In practice at 100 Hz you can't detect
anything farther than about a meter from the detector.
jeg
t 11:22 AM 12/5/97 -0500, Kyle wrote:
I'd like to know if you get any additional information about this. I have
had a similar problem with the motion sensor attached to a CBL pointing
upward towards a mass on a spring with a styrofoam plate taped to the
underside: Good results with times of 4 or more seconds of data collection,
bad results (the sine wave interupted with erratic data) with times less
than 4s. I thought possibly I had made a programing error (I modified one
of the Vernier programs) and was telling the CBL or the detector to take
data faster than was possible (but I was too lazy to go back and check).
Although the CBL Sonic channel can take a minimum sample time of 0.008s
there is a note in the CBL System Guidebook that says the actual minimum
sample time depends on the detector (and this is not given in the sensor
info sheet).
My solution so far (until I have a chance to look at it) has been to tell
students to use 4 or more seconds...
kyle
__________________________________
John E. Gastineau gastineau@mindspring.com KC8IEW
900 B Ridgeway Ave. http://gastineau.home.mindspring.com
Morgantown WV 26505 (304) 296-1966