Views:

 

Applies To: 1502A

Problem Description: When the filter is set, how does the filter function?

Resolution/Work Around: 

The filter is a digital exponential filter.  It has an exponential decay with a time constant that is approximately <FI> seconds.

The exponential filter simulates a 1-pole analog filter where more recent measurements are given more weight than earlier measurements.  The exponential filter the response time is the time required for the output to reach 63% of its final value with a step change in the input.  There is a trade-off between response time and smoothing effectiveness.  Increasing the response time smooths the measurements and improves the effective resolution.  However, if the response time is too long you will not be able to accurately measure changing temperatures.  The response time of the filter should be set to the smallest value that achieves the desired resolution and accuracy.  You can set it to any value between 0 and 60 seconds.  A value of 0 disables the filter.  The default time constant is 4 seconds.