C2 Series User Manual Rev. 1.9   
 23 
The FIR Filter Function 
The FIR filter is a signal processing function aiming to increase the precision of laser line detection in 
the sensor image. It consists of a digital Finite Impulse Response filter (FIR) and can be operated in a 
smoothing or differentiating mode. 
 
FIR in smoothing mode (in combination with MAX, TRSH and COG algorithms): 
 
 
 
 
 
 
 
 
 
FIR in differentiating mode (FIR PEAK): 
 
 
 
 
 
 
 
 
Pre-defined templates with 5, 7 or 9 coefficients let the FIR filter to be customised to the Gauss size 
and shape of the application. 
 
More  details  regarding  the  operation  of  the  FIR  filter  function  can  be  found  in  a 
separate application note. 
 
 
Zero-Crossing of 
First Derivative