[Code of Federal Regulations]

[Title 47, Volume 1]

[Revised as of October 1, 2005]

From the U.S. Government Printing Office via GPO Access

[CITE: 47CFR15.211]



[Page 817]

 

                       TITLE 47--TELECOMMUNICATION

 

              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 

conditions:

    (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.



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