PT1 Filter

A PT1 filter is a transfer function that performs convex interpolation between a new value x_n and an old value (from one cycle before) x_a. The filter time parameter, a nonnegative value in the unit of seconds, has to be entered into the calculation. If I = SAF cycle time / (SAF cycle time + filter time), then x = I * x_n + (1-I) * x_a. The filter time should be finite. For the filter time being a positive value I resides within the open interval from 0 to 1. If the filter time is close to 0.0, the new value has a high weighting. If the filter time is long, the older value has a relatively high weighting.