This is basically a question about "signal processing". But since a potential solution comes to mind involving ferrites on a radio's transmission line, I am posting the question here in this "Antennas, Feedlines, Towers & Rotors" forum. From comments I've read about digital signal processing (DSP) and software-defined radio, I imagine an excellent, easily adaptable, general solution might be DSP in a digital processor interposed between the feedline and the radio (especially the radio as receiver and especially for doing DX communications). But that approach seems likely to be fairly costly and may perhaps involve more rigmarole than necessary. So the legacy, analog approach to signal processing of adding ferrites (ferrite beads and/or ferrite toroids) to the feedline near the radio comes to mind as potential solution for all noise problems arriving over the feedline. This question applies to both HF and VHF reception. I am planning installation of an HF antenna system ("fan" inverted V for 40m/20m), and so this question is applicable to that system as well as my existing VHF/UHF system. Basically, the question comes down to this: Can ferrites on the receiving feedline suppress "scratchy" noise that is transmitted by a remote station as part of the transmitted signal? The main source of my question comes from the fact that I received a fairly noisy ("scratchy") yet still readable signal via listening to a cross-band repeater on a 70cm frequency but when I switched to listen on the 2m frequency that the originating station was transmitting on, his signal I heard was very clear and noise-free, and moreover, I received other stations very clearly via listening to the cross-band repeater's 70cm output. So it seems the noise was not originating in the cross-band repeater's transmission or from extraneous sources after that transmission but was originating from the cross-band repeater's signal as received, perhaps with noise mixed in from the repeater's receiver itself. What was the exact originating source(s) of that noise is not clear, but it seems that the noise I heard was being transmitted as part of the repeater's outgoing signal. And I'm guessing that the noise could be characterized as "noise-modulated RF", but I'm not sure what that really means in the case of this kind of noise. ( In other words, I'm wondering if "noise-modulated RF" is really a well-defined concept when the noise may have a very broad spectrum.) The character of the "scratchy" noise did not sound like the "soft", pure white-noise "hiss" like one might hear in an audio system amplifier with the volume turned up. But rather the noise sounded more harshly like hot, frying bacon with perhaps some moisture in the mix -- i.e., so that the noise tends to have a "crackling" or "popping" component. So I image the noise spectrum will look very different in these two cases (pure hiss or frying bacon). Now this question is also relevant to the HF antenna system I am planning. I have a vintage Yaesu FT-767GX transceiver which I have used to receive SSB on 40m via my Comet CX-333 tri-band VHF/UHF antenna. I can hear SSB stations, but I generally have to turn down the noise squelch all the way in order to hear those stations. So I get an awful lot of received noise as a result. If I recall correctly, it also sounded a bit like frying bacon. I am hoping the noise will be greatly reduced when I get my HF antenna system set up. So I am wondering just how much noise can be suppressed with ferrites in the new HF set-up. Will there still be noise that cannot be eliminated using ferrites? Would using a microcontroller package (such as, say, Raspberry Pi with appropriate DSP open-source software) as a front-end to the receiver be needed to substantially remove a lot of the noise?