|The Federal Communications Commission (FCC) is the authority
in the United States of America that creates and enforces the use of airwaves throughout the entire
radio frequency spectrum. This group of documents contains the entirety of the
FCC Part 15 regulations
that concern unlicensed radio frequency devices. As with all government documents, this material
is in the public domain and may be freely copied so long as the content is not changed. This copy
is provided as a convenience for RF Cafe visitors.
Click here for the
Table of Contents.
[Code of Federal Regulations]
[Title 47, Volume 1]
[Revised as of October 1, 2008]
From the U.S. Government Printing Office via GPO Access
CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION
PART 15_RADIO FREQUENCY DEVICES--Table of Contents
Subpart C_Intentional Radiators
Sec. 15.211 Tunnel radio systems.
An intentional radiator utilized as part of a tunnel radio system
may operate on any frequency provided it meets all of the following
(a) Operation of a tunnel radio system (intentional radiator and all
connecting wires) shall be contained solely within a tunnel, mine or
other structure that provides attenuation to the radiated signal due to
the presence of naturally surrounding earth and/or water.
(b) Any intentional or unintentional radiator external to the
tunnel, mine or other structure, as described in paragraph (a) of this
section, shall be subject to the other applicable regulations contained
within this part.
(c) The total electromagnetic field from a tunnel radio system on
any frequency or frequencies appearing outside of the tunnel, mine or
other structure described in paragraph (a) of this section, shall not
exceed the limits shown in Sec. 15.209 when measured at the specified
distance from the surrounding structure, including openings. Particular
attention shall be paid to the emissions from any opening in the
structure to the outside environment. When measurements are made from
the openings, the distances shown in Sec. 15.209 refer to the distance
from the plane of reference which fits the entire perimeter of each
above ground opening.
(d) The conducted limits in Sec. 15.207 apply to the radiofrequency
voltage on the public utility power lines outside of the tunnel.