Roofing filter: Meaning (information, definition, explanation, facts)

A roofing filter ist usually a filter in a hf-receiver after the first receiver-mixer. The goal of a roofing filter is to reduce the pass-band of the 1. intermediate frequency to about 6-20 kc, so that overloading and distortions by the following amplifier stages and mixers are reduced. The receivers bandwidth is not performed by the roofing filter but by a following crystal-filter or mechanical-filter or DSP-filter, which allow much better filtering curve than a roofing filter, which usually uses a high 1. IF of higher than 40 Mc. Because of this, roofing filter are usually crystal-filter types.