#### omid2006

##### Junior Member level 2

I found a unknown digital low pass filter in a sample code but I can't adapt it's formula with common filters like IIR because it's like a IIR filter with negative coefficient. it's like feedback filter but feedback filter is a highpass in ordinary and this filter is low pass. I'll write it's formula and I appreciate if anyone can help.

Code:

`out[n]+=(in[n]-out[n-1])*500*Ts`

and Ts is the sampling frequency thus execution rate of filter.