A method of recognizing a radar target comprises producing a sequence of Doppler spectra of radar returns form a scene and producing therefrom a sequence of Doppler feature vectors for a target in the scene. The oronasal cup encloses a nose and mouth of a user. The current sense based MPS device also comprises a current generator configured to sink electrical current to prevent the PSE from removing power to the PD. Each process node has an interface card that formats the data for a high speed interface bus that is coupled to the interface card.