Now that I look at this chart for a bit I realize its the radio equiv of the Vignelli map of NY subway. It looks nice, it feels like good design, but its actually unusable. The Y axis within each spectrum isn't used for any meaning other than just dividing into halves, thirds, quarters whatever. Sometimes there's two or more boxes of the same color and label in the same spectrum with no explanation about what distinguishes them. It color codes every minor distinction in application with its own color, which actually makes it less clear.

Here's my first pass at a redesign. All the categories are reallocated into a 2-feature category system, (Sea, Land, Air, Space) x (Science, Navigation, Communication, Broadcast). The first half-category goes on the y axis of each spectrum bar. So all the space stuff is along the top of the sub-spectrum chart, all the sea stuff along the bottom. The second half category goes into a color, of which there's only 4. The existing color stripe for federal/non-federal is good as is, but could perhaps also include operator type more generally (military/civilian/government/public, reserved etc).