Tim Shepard KD1KY will give you a different perspective on why the radio spectrum needs regulation... or doesn't. Tim rounded out the Friday sessions at the 2017 ARRL/TAPR DCC in St. Louis. This talk works well as audio: DOWNLOAD/LISTEN
Painful to listen to because he seems only to have coherent thoughts when looking at his Power Point presentation. He has some interesting ideas but the delivery is like waiting for grass to grow.
He is raising some points that are academic for this audience. E.g., replacing the receiving apparatus with a different one to get rid of QRM. That might be worth studying for the US Navy, who can build spatially-diverse antennas separated by acres or miles or degrees of longitude, but for the ham community, it's a meaningless (even if interesting) point. The reason FCC regulates interference at the transmitter is because that's the only practical approach for the majority of spectrum users. Other points (e.g., the scalability of packet on VHF or UHF) are mostly academic because they only apply in the few big cities where traffic density is high enough for people to practice those modes. About half-way through he concedes that he can't think of a better way to do regulation of spectrum for frequencies lower than VHF-ish. Since most ham bands above that are nearly empty of usage in most places in the US, I'm not sure that his talk makes sense for an amateur audience. For the LMR crowd, it's a whole different story, because those folks are fighting to squeeze more frequencies in less space all the time. But for most hams, there's not much here.
This is my number one pet peeve with presentations. Talk faster! Talk as fast as you can and then talk faster than that.
This is why I prefer to read articles than watch YouTube videos. When the presenter writes an article that I can read, I can make them talk as fast as I want.
Most podcast apps have a speed control. It looks like YouTube might, too, as a Chrome extension, but I haven't played with it.
Not a meaningless point... Diversity Reception is absolutely achievable for a Ham Station since spatially-diverse antennas need as little as one Wavelength of separation to be effective. Diversity Reception is important where Radio Communications must be reliable. Most Hams are not familiar with Diversity Reception because most Ham Communications do not require reliability. IMO it is a concept 'over looked' by the Ham Community.
Ah yes, you are absolutely correct. I even experimented with something similar once upon a time, and had completely forgotten some of the details. I guess I need to re-read some of my own writings.
My ICOM 2820 D-STAR mobile has two antenna ports for diversity reception. I don't dedicate two antennas to the radio, but I played with it some just to see. It did reduce mobile picket-fencing some (on FM).