Sensitive frequencies now available to companies developing medical devices.
A small fraction of frequency bands need extraordinary protection from radio interference. Some, like those used for radio astronomy, depend on extremely sensitive receivers. Others carry signals essential to safety, like search-and rescue bands and GPS, which helps to land airplanes as well as to find pizza in a strange city.
The FCC’s licensing regime protects these bands from high-powered transmitters. But as unlicensed transmission sources – which now include Wi-Fi, Bluetooth, car-door openers, and thousands more – began to proliferate in the 1980s, they posed a threat. These devices can be used by anybody anywhere, including locations where they might cause interference.
The FCC sat down with the National Telecommunications and Information Administration, which administers spectrum use by government agencies, and together they drew up a list of about 40 bands potentially vulnerable to unlicensed radios. See the list here. The FCC calls them “restricted bands.” It adopted a rule requiring manufacturers to ensure that transmitting devices marketed for unlicensed use cannot operate on any of them.
But only temporarily. For the last 15 years, the FCC has been chipping away at the protections. Ultra-wideband devices, first authorized in 2002, are allowed to operate in some of these bands. The FCC has also allowed various forms of wideband radar to use the bands, including airport radars, the vehicle radars used for automatic braking and lane-change monitoring, and some industrial radars. All of these are a particular concern to radio astronomers, who operate the most sensitive receivers on the planet capable of picking up signals from billions of light-years away. To them, a car-mounted radar just a few miles off can be a problem. Also threatened is earth-exploration-satellite research, which uses orbiting receivers for scientific study of the Earth. Because the receivers point to everywhere on the globe, they too are vulnerable to interfering signals in their bands.
The restricted-band users just took an additional hit.
The FCC has long granted “experimental licenses” to researchers, basement hobbyists, and pretty much anybody else who wants to tinker with radio gear. Needless to say, the FCC has not been inclined to issue experimental licenses authorizing operation in the restricted bands.
The downside to experimental licenses, for an active researcher, has been the need to get a new one every time there is a technical change to the equipment being used or investigated. Back in 2013, the FCC announced three new kinds of experimental licenses to help solve this problem: a “program experimental license” for universities, research labs, manufacturers, etc.; a “medical testing license” for health facilities conducting clinical trials; and (not relevant here) a license for commercial test labs. These all make it easier to work with multiple types of radio transmitters.
Medical testing licensees are allowed to transmit in a restricted band at 401-406 MHz. That band is used for earth-exploration-satellite research and meteorological research and monitoring – and also for medical telemetry at very low power. A manufacturer of medical devices, apparently eligible for a program license but not a medical testing license, requested access to 401-406 MHz for its development work. It got more than that: the FCC has changed the rule to let program licensees use frequencies in any restricted band when testing medical devices. The only limitation: devices under test must comply with whatever power limits and other technical rules would apply to the device if it were placed on the market. The revised rule will take effect 30 days after the FCC’s order is published in the Federal Register; check back with us here for updates on that front.
They say the Great Wall of China really isn’t really visible from space. Earth-exploration-satellite researchers are hoping the same is true of medical devices.