Note that the search continues to limit the effects of stray or planned disturbances of electronic devices. The use of PFO (Plastic Fiber Optics) is now cost effective and since most EMP uses the copper conductor as an antenna then one more source of input is gone. YMMV
EMI is another name for RFI or radio frequency interference. "Radiated EMI or RFI may be broadly categorized into two types; narrowband and broadband. Narrowband interference usually arises from intentional transmissions such as radio and TV stations, pager transmitters, cell phones, etc. Broadband interference usually comes from incidental radio frequency emitters. These include electric power transmission lines, electric motors, thermostats, bug zappers, etc. Anywhere electrical power is being turned off and on rapidly is a potential source. The spectra of these sources generally resemble that of synchrotron sources, stronger at low frequencies and diminishing at higher frequencies, though this noise is often modulated, or varied, by the creating device in some way. Included in this category are computers and other digital equipment as well as televisions. The rich harmonic content of these devices means that they can interfere over a very broad spectrum. Characteristic of broadband RFI is an inability to filter it effectively once it has entered the receiver chain" Electromagnetic interference - Wikipedia, the free encyclopedia
