1. A system comprising: an averaging persistence filter configured to capture a persistent portion of a digital signal and to remove a non-persistent portion of the digital signal, the averaging persistence filter comprising: an interface configured to receive the digital signal; and one or more processors, coupled to the interface, configured to: aggregate a plurality of digital signal sample sets of the digital signal to generate aggregated results; scale the aggregated results using selective ones of a plurality of coefficients to generate a plurality of linear reference components of the digital signal; aggregate the plurality of linear reference components; and determine an output based on the aggregated plurality of linear reference components.