Microsonic LCA-2 - Manual (Page 30)

Page 30 of 51 Changing parameters on distance measuring sensors
A VERAGE
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FILTER
The filter method average simulates an arithmetic mean value calculation over several measurements.
The scroll bar for Attenuation determines how many elapsed measurements shall be taken into account to
form the mean. The resulting settling time for the measurement value to follow a sudden distance jump is
calculated from the time for a single ultrasonic measurement multiplied by the number of measurements,
which are taken into account.
The applied method is not exactly a true mean value calculation from the mathematical point of
view; due to the limited RAM storage capacity of a microcontroller a similar method is employed.
The maximum allowable attenuation should experimentally be derived.
Example
The filter method average is suited especially for analogue sensors in applications, where an attenuation
of the measured distance for both moving directions is needed. Typical applications are coil winding, loop
con-troll and level detection...
On slow processes often the highest filter setting may be chosen. Short term error target, for instance a
fast moving hand through the ultrasonic beam, does hardly affect the output signal.