A three dimensional (3-D) spatio-temporal analog signal processing scheme is presented for the selective removal of off-dish interference and noise from focal plane array (FPA) received signals. The method exploits specific geometrical properties of the 3-D spatio-temporal frequency spectrum of FPA signals to perform the filtering operation. A 3-D infinite impulse response (IIR) filter having a cone-shaped filter passband in the 3-D spatio-temporal frequency space is employed to extract the spectra of desired FPA signals while rejecting the spectral components from undesired off-dish interference and coupled noise from front-end electronics. A proof-of-concept example is provided by considering the filtering operation in 3-D spatio-temporal frequency domain.