Radio reps- get moving
I seems to me that when you talk about "undesirables" in the hobby, what you are really afraid of is that the "rogue" fliers out on the schoolyard will pollute the usable frequencies so that it's no longer safe to fly without getting a hit.
The obvious solution to this problem is to make it impossible to get a hit. That can be easily done if Tx and Rx are able to expand on PCM technology by sending "headers" with each transmission that uniquely identifies the code sent as belonging to your TX and not someone else's. If your Rx can disregard bogus input then the problem is solved.
I think that the reason that this type of modulation has not been implemented is that (and I'm guessing here) this sort of transmission would require more bandwidth than is currently available with the sub-bands (50 channels) within the 72 mHz band. For example it may be that putting channel 50 and 49 together would provide the necessary modulation range. If this is so, then it would require the FCC to combine some channels. Can you imagine how many years it would take to even get them to consider the idea let alone implement it?
By the way, if anyone out there is saying to themselves that this would never work because there are still radios out there that will still use channels 49 & 50 in the same old way. But that really doesn't matter because they just need to be aware that 49 and 50 are no longer safe for them in the same way that certain areas of the country are susceptible to Pager interference on a few channels.
Any thoughts on this guys?