06/17/2016
Radio amateurs frequently complain about increasing noise from a variety of
sources, so it should be welcome news that the FCC Technological Advisory
Council (TAC[1]) - an advisory group to the FCC - is investigating changes and
trends to the radio spectrum noise floor to determine if there is an increasing
noise problem, and, if so, its extent. The FCC Office of Engineering and
Technology (OET) announced[2] the TAC study this week in a Public Notice and
invited comments[3] and answers to questions that the TAC has posed in the
notice. The comment deadline is August 11. The TAC said it is trying to
determine the scope of any noise issues and has invited "quantitative evidence"
of noise problems, as well as recommendations on how to perform a noise study.
"The TAC is requesting input to help answer questions about the study of
changes to the spectrum noise floor over the past 20 years," the announcement
said. "Noise in this context denotes unwanted radio frequency (RF) energy from
manmade sources. Like many spectrum users, TAC members expect that the noise
floor in the radio spectrum is rising as the number of devices in use that emit
radio energy grows."
The ARRL representative on the TAC, Greg Lapin, N9GL, co-chairs the TAC
Spectrum and Receiver Performance Working Group with Lynn Claudy of the
National Association of Broadcasters. Lapin also serves as chairman of the ARRL
RF Safety Committee.
The TAC said that its search for "concrete evidence of increased noise floors"
has turned up only "limited available quantitative data" to support its
presumption of a rising noise floor. The TAC said it wants to find ways to add
to the available data so it can "answer important questions" on the topic for
the FCC.
The TAC noted that many types of devices generate radio spectrum noise. In the
case of incidental radiators - devices not designed to emit RF but do so anyway
- there is little regulation governing such noise. "Most electric motors, light
dimmers, switching power supplies, utility transformers, and power lines are
included in this category," the TAC announcement explained.
Devices designed to generate RF for internal use, or send RF signals to
associated equipment via connected wiring, but which are not intended to emit
RF energy, are called unintentional radiators. This category includes computers
and many portable electronic devices, as well as many new high-efficiency
lamps. FCC regulations limit the levels of emitted RF energy from these
devices.
A third group of devices categorized as intentional radiators (unlicensed and
licensed) and industrial, scientific, and medical (ISM) radiators - are
designed to generate and emit RF energy by radiation or induction. Intentional
radiators include cellular phones and base stations, unlicensed wireless
routers, Bluetooth devices, broadcast TV and radio stations, and radar systems.
Amateur Radio transmitters also fall into this category. Microwave ovens, arc
welders, and fluorescent lighting are examples of ISM equipment.
"Such emitters contribute to the noise floor with emissions outside of their
assigned frequencies," the TAC said. "These are sometimes generated as spurious
emissions, including, but not limited to, harmonics of desired frequencies and
intermodulation products." FCC regulations permitting the operation of these
devices specify emission limits outside of the device's licensed or permitted
operating frequencies.
The TAC said that responses to the questions it has posed in the Public Notice
will help it to "identify aspects of a study to determine trends in the radio
spectrum noise floor." The Public Notice[4] includes information on all methods
of responding to the inquiry. The ARRL is planning to comment.
For more information, contact[5] Greg Lapin, N9GL.
[1] https://www.fcc.gov/general/technological-advisory-council
[2] http://transition.fcc.gov/Daily_Releases/Daily_Business/2016/db0615/DA-16-67
6A1.pdf
[3] http://fjallfoss.fcc.gov/ecfs2/
[4] http://transition.fcc.gov/Daily_Releases/Daily_Business/2016/db0615/DA-16-67
6A1.pdf
[5] mailto:glapin@arrl.org
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