FM does it with frequency!
Some models of the RVR STL transmitters--and receivers, don't have very well shielded IF oscillators. Had problems at a combined site when two receivers were put too close together in the rack. At another site, the STL transmitter blocked out a weather receiver used for EAS. Moving it to a window cured the problem, later replaced the "home" style wx receiver with a Gorman Redlich.