# PT1-filter

## Frequency response

The PT1 filter has the transmission response of a first order delay element. Contrary to the other axis filters, it is parameterised by specifying a time constant (filter[i].time_constant). No filter prototype needs to be specified for this filter type. To activate the filter, an order > 1 (filter[i].order) must be set.

Time constant of the PT1 filter

The figure shows the amplitude response of the PT2 filter depending on the filter[i].time_constant.

## Example

Axis filters: PT1 filter with time constant of 0.01 seconds:

filter[0].enable | 1
filter[0].order | 1
filter[0].type | PT1
filter[0].time_constant | 10000
filter[0].share_percent | 100

## Example

Additional interface: PT1 filter with time constant of 0.01 seconds

Lr_param.add_interface.enable | 1
lr_param.add_interface.filter[0].enable | 1
lr_param.add_interface.filter[0].order | 1
lr_param.add_interface.filter[0].type | PT1
lr_param.add_interface.filter[0].time_constant | 10000
lr_param.add_interface.filter[0].share_percent | 100