About the Data Logger

Introduction	next	previous

Drag Measurement on HPVs

The Evaluation Software

Most of the evaluation software is straight forward as described in the theory section. However, some effort has been put into a smoothing differentiation algorithm and into an error estimate for the resultant data. The differentiation works as linear approximation within a region of points around the differentiated coordinate. With an appropriate choice of the region size, most of the noise can be eliminated. For details see the source of the program:

ftp://hal.kph.tuwien.ac.at/pub/HPV/coastdown/cook.c

This program was only tested on NEXTSTEP. It should compile without changes on most Unix machines. It should also be easily portable to DOS/Windows. In its current implementation the data from the data logger is taken from a file and the F(v)-data and the curve fit results are printed to the standard output (on the screen). The output data consists of three columns: the speed in m/s, the force in N and the statistical error of the force in N. An example can be found in the table of my measurements.

Introduction next previous

Author: Christian Starkjohann <cs@hal.kph.tuwien.ac.at>