A communications receiver has four filters installed in it, respectively designated as 250 Hz, 500 Hz, 2.4 kHz, and 6 kHz. If you were listening to single sideband, which filter would you utilize?

Different modulation modes require different filter bandwidths to properly pass the signal while rejecting adjacent noise. The general rule is to match the receiver's filter as closely as possible to the bandwidth of the transmitted signal. A standard Single Sideband (SSB) voice signal occupies approximately 2.4 kHz to 3 kHz of bandwidth. Therefore, the 2.4 kHz filter is the perfect choice to let the voice frequencies through without cutting off information or letting in excess noise. The narrower filters (250 Hz and 500 Hz) are meant for CW (Morse code) or very narrow digital modes, which have a much smaller footprint. The 6 kHz filter is suited for standard AM voice, which is exactly twice as wide as an SSB signal.