[[Fil:Afu superhet1.svg|thumb|En traditionel amatørradio blokdiagram (dobbelsuper). ''Roofing-filteret'', her et [[krystalfilter]] med stor båndbredde, er den tredje blok fra venstre, efter radioantenneindgangen.]]
Et '''''roofing-filter''''' er et [[Elektronisk filter|filter]], der bruges i en [[Superheterodynmodtager|superheterodynsystem]] (fx i en [[kortbølgemodtager]] og [[kortbølgetransceiver]]) med mere end en [[Mellemfrekvens (radioteknik)|mellemfrekvens]]. Et ''roofing-filter'' findes efter den første [[Elektronisk mikser|mikser]]. Målet med et ''roofing-filter'' er at begrænse [[Båndbredde (signalbehandling)|båndbredden]] fra første mellemfrekvens (1. MF).<ref name="elecraft">[https://elecraft.com/pages/k3s-crystal-roofing-filters elecraft.com: K3S Crystal 'Roofing' Filters. What "Roofing Filter" means to Elecraft. Wayne Burdick, N6KR] Citat: "...A "Roofing filter" is simply a filter in the radio's first IF through which all signals must pass before they will be "seen" by later receiver stages. The narrower this filter is, the less exposure later stages will have. Thus a "narrow" roofing filter is desirable -- but "narrow" is relative, as I'll explain. ...A roofing filter protects later stages, including amplifiers, mixers, narrower filters, and DSP subsystems, just as the roof on your house keeps rain out of all of the rooms. But a roofing filter can be equally at home at a low first IF, if that is how the radio is designed. It still provides the same protective function...So why don't they offer much narrower roofing filters that can be switched in for CW and data modes, or at times when adjacent-channel SSB QRM is very high? It's because they can't make filters any narrower at such a high IF...", [https://web.archive.org/web/20220128225601/https://elecraft.com/pages/k3s-crystal-roofing-filters backup]</ref> Stærke signaler uden for [[radiokanal]]en, som kan forårsage [[overstyring]] og dermed [[forvrængning]] og [[intermodulation]] af de følgende [[forstærkertrin]] og miksere. Herudover kan disse trin blive [[Signalblokering|signalmæssigt blokeret]].
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