I have to wonder how well the RCA system worked. As far as I know, the system didn't survive. Was it a case that it really didn't perform well in the real world? It was better on paper than practice (like at least the early years of the audio CD)? Or did it perform well for the time, but get surpassed a few years later? Or was it a great or potentially system that, for whatever reason, fell by the wayside? (I personally have to doubt this last item; however, one never knows-- I have written off too many technologies just to be proven wrong, so I don't casually write anything off anymore!) In any case, it would be interesting to have this RCA system in working order to play with.
Also I wonder if other radio companies didn't have a system like this. I seem to recall having seen a vintage ad like this before, but I THINK it was Philco. But maybe my memory is faulty....