|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. 15.251 Operation within the bands 2.9-3.26 GHz, 3.267-3.332
GHz, 3.339-3.3458 GHz, and 3.358-3.6 GHz.
(a) Operation under the provisions of this section is limited to
automatic vehicle identification systems (AVIS) which use swept
frequency techniques for the purpose of automatically identifying
(b) The field strength anywhere within the frequency range swept by
the signal shall not exceed 3000 microvolts/meter/MHz at 3 meters in any
direction. Further, an AVIS, when in its operating position, shall not
produce a field strength greater than 400 microvolts/meter/MHz at 3
meters in any direction within 10 degrees of the
horizontal plane. In addition to the provisions of Sec. 15.205, the
field strength of radiated emissions outside the frequency range swept
by the signal shall be limited to a maximum of 100 microvolts/meter/MHz
at 3 meters, measured from 30 MHz to 20 GHz for the complete system. The
emission limits in this paragraph are based on measurement
instrumentation employing an average detector. The provisions in Sec.
15.35 for limiting peak emissions apply.
(c) The minimum sweep repetition rate of the signal shall not be
lower than 4000 sweeps per second, and the maximum sweep repetition rate
of the signal shall not exceed 50,000 sweeps per second.
(d) An AVIS shall employ a horn antenna or other comparable
directional antenna for signal emission.
(e) Provision shall be made so that signal emission from the AVIS
shall occur only when the vehicle to be identified is within the
radiated field of the system.
(f) In addition to the labelling requirements in Sec. 15.19(a), the
label attached to the AVIS transmitter shall contain a third statement
regarding operational conditions, as follows:
* * * and, (3) during use this device (the antenna) may not be
pointed within ** degrees of the horizontal plane.
The double asterisks in condition three (**) shall be replaced by the
responsible party with the angular pointing restriction necessary to
meet the horizontal emission limit specified in paragraph (b).
(g) In addition to the information required in subpart J of part 2,
the application for certification shall contain:
(1) Measurements of field strength per MHz along with the
intermediate frequency of the spectrum analyzer or equivalent measuring
(2) The angular separation between the direction at which maximum
field strength occurs and the direction at which the field strength is
reduced to 400 microvolts/meter/MHz at 3 meters;
(3) A photograph of the spectrum analyzer display showing the entire
swept frequency signal and a calibrated scale for the vertical and
horizontal axes; the spectrum analyzer settings that were used shall be
labelled on the photograph; and,
(4) The results of the frequency search for spurious and sideband
emissions from 30 MHz to 20 GHz, exclusive of the swept frequency band,
measuring instrument as close as possible to the unit under test.
[54 FR 17714, Apr. 25, 1989; 54 FR 32340, Aug. 7, 1989]