The US Federal Communications Commission is trying to figure out exactly how much trouble is being caused by radio noise.
Many devices emit radio frequency energy that could interfere with radio services and increase the "radio spectrum noise floor," essentially the sum of all unwanted signals. The FCC is planning to study changes to the noise floor from human-made sources over the past 20 years.
It's commonly believed that "the noise floor in the radio spectrum is rising as the number of devices in use that emit radio energy grows," but the FCC said it hasn't found much quantitative data to support this presumption. As a first step toward the FCC producing such a study, the commission last week asked the public for input on the proper design of the study and input on the problem itself.
While there are already regulations limiting RF energy emissions, not all devices are regulated equally. The FCC inquiry notes that "incidental radiators" face little regulation and asks, "what sorts of government, industry, and civil society efforts might be appropriate to ameliorate the noise they produce?"
"Radio spectrum noise is generated by many different types of devices. Devices that are not designed to generate or emit RF energy but do so as a result of their operation are called Incidental Radiators," the FCC said. "Most electric motors, light dimmers, switching power supplies, utility transformers and power lines are included in this category. There is little regulation governing the noise generated by these devices. Noise from such sources is expected to be minimized with 'Good Engineering Practices.'"
The FCC mentioned several other classes of devices that can increase the noise floor. One category is "unintentional radiators" such as computers, portable electronic devices, and high-efficiency lights, which "send RF signals by conduction to associated equipment via connected wiring, but are not intended to emit RF energy." There are regulations limiting the levels of RF energy that can be emitted from these devices.
There are also devices that are "designed to generate and emit RF energy by radiation or induction." Cellular phones and base stations, wireless routers, Bluetooth devices, broadcast TV and radio stations, radars, microwave ovens, arc welders, and fluorescent lighting all fall in this category.
Despite regulations covering these devices, "Such emitters contribute to the noise floor with emissions outside of their assigned frequencies," the FCC said. "These are sometimes generated as spurious emissions, including, but not limited to, harmonics of desired frequencies and intermodulation products."
After this description, the FCC public notice asks a series of questions, such as what are the most likely major sources of noise, what radio services are being affected the most by a rising spectrum noise floor, and at what levels does the noise floor cause harmful interference to particular radio services. The FCC further asks what frequency bands are of most interest, whether the problem is most pronounced indoors or outdoors, whether cities or rural areas are most problematic, and whether noise varies by season or time (night vs day). Finally, the FCC asks for specific ideas on how to conduct a noise study.
Responses can be submitted here (make sure to specify the proceeding number, 16-191). The first comment comes from a longtime ham radio operator named William Gray, who says that interference in the past few years has "gotten much worse." Gray said that amateur radio services are "easily overwhelmed" by noise because they need to receive low-strength signals.
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