s amateur radio operators, most of us are familiar with the HF spectrum, plus VHF, UHF, and even microwaves, so what remains? As I mentioned previously, there are other areas that can be explored by our community. These can, perhaps, open areas that are not commonly used for routine communications, especially by experimenters who are not “locked down” with currently accepted limitations. One of these is communications via sound waves, and I don’t mean by just talking! I mean by a method that – while similar to
