Editing Unintentional radiator (section)

==Regulatory overview==
In North America, active devices that are characterized as unintentional radiators are governed by [[Title 47 CFR Part 15|Part 15]] of the [[Federal Communications Commission|FCC]] regulations. In Canada, [[Innovation, Science and Economic Development Canada|Innovation, Science and Economic Development]] considers them as interference-causing [https://www.ic.gc.ca/eic/site/smt-gst.nsf/eng/h_sf06127.html Equipment]. Globally, most domestic regulation of unintentional radiators are based on [[ITU]] recommendations.

Generally, this means the device leaks a signal at some level. Microprocessor-controlled appliances, anything with a [[clock signal]], and [[switching voltage regulator]]s all make some kind of noise, at the repetition frequency and at harmonics. In most countries, government agencies regulate how much leakage is tolerated. This prevents leakage from [[cable television]] systems, for example, from interfering with radio communications between aircraft and [[control tower]]s.

Because it costs money to filter out noise, there is always a balance struck between regulatory compliance and perfect filtering in these devices. [[Microwave oven]]s or devices with microprocessors may leak within allowable limits but may generate an undesired signal that interferes with a licensed communications device. It also generally means that users who intentionally radiate signals ([[Television|TV stations]] and [[Cellular telephone|cell phone]] companies) can order the device turned off if it interferes with their licensed operations.

[[Image:Cable end.JPG|thumb|right|Ferrite bead at the end of a [[USB]] cable]]
There is an entire industry based on [[Compliance (regulation)|regulatory compliance]]: manufacturers shipping a product to a foreign country must comply with each country's limitations on leakage of interfering signals. For example, in Germany the [[Technischer Überwachungsverein|TÜV]] issues regulatory rules for unintentional radiators. The big cylindrical bumps on the cable to monitors and laptop chargers are [[ferrite bead|ferrite cores]] which reduce undesired signals.