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FCC Part 15 Radio Frequency Devices
Section 15.252

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
[CITE: 47CFR15.252]
[Page 825-826]
 
                       TITLE 47--TELECOMMUNICATION
 
              CHAPTER I--FEDERAL COMMUNICATIONS COMMISSION
 
PART 15_RADIO FREQUENCY DEVICES--Table of Contents
 
                     Subpart C_Intentional Radiators
 
Sec. 15.252  Operation of wideband vehicular radar systems within the
bands 16.2-17.7 GHz and 23.12-29.0 GHz.

    (a) Operation under this section is limited to field disturbance 
sensors that are mounted in terrestrial transportation vehicles. 
Terrestrial use is limited to earth surface-based, non-aviation 
applications. Operation within the 16.2-17.7 GHz band is limited to 
field disturbance sensors that are used only for back-up assistance and 
that operate only when the vehicle is engaged in reverse.
    (1) The -10 dB bandwidth of the fundamental emission shall be 
located within the 16.2-17.7 GHz band or within the 23.12-29.0 GHz band, 
exclusive of the 23.6-24.0 GHz restricted band, as appropriate, under 
all conditions of operation including the effects from stepped 
frequency, frequency hopping or other modulation techniques that may be 
employed as well as the frequency stability of the transmitter over 
expected variations in temperature and supply voltage.
    (2) The -10 dB bandwidth of the fundamental emission shall be 10 MHz 
or greater. For transmitters that employ frequency hopping, stepped 
frequency or similar modulation types, measurement of the -10 dB minimum 
bandwidth specified in this paragraph shall be made with the frequency 
hop or step function disabled and with the transmitter operating 
continuously at a fundamental frequency following the provisions of 
Sec. 15.31(m).
    (3) For systems operating in the 23.12-29.0 GHz band, the 
frequencies at which the highest average emission level and at which the 
highest peak level emission appear shall be greater than 24.075 GHz.
    (4) These devices shall operate only when the vehicle is operating, 
e.g., the engine is running. Operation shall occur only upon specific 
activation, such as upon starting the vehicle, changing gears, or 
engaging a turn signal. The operation of these devices shall be related 
to the proper functioning of the transportation vehicle, e.g., collision 
avoidance.
    (b) Emissions from a transmitter operating under this section shall 
not exceed the following equivalent isotropically radiated power (EIRP) 
density levels:
    (1) For transmitters operating in the 16.2-17.7 GHz band, the RMS 
average radiated emissions above 960 MHz from a device operating under 
the provisions of this section shall not exceed the following EIRP 
limits based on measurements using a 1 MHz resolution bandwidth:

------------------------------------------------------------------------
                                                                EIRP in
                       Frequency in MHz                           dBm
------------------------------------------------------------------------
960-1610.....................................................      -75.3
1610-16,200..................................................      -61.3
16,200-17,700................................................      -41.3
Above 17,700.................................................      -61.3
------------------------------------------------------------------------

    (2) For transmitters operating in the 23.12-29.0 GHz band, the RMS 
average radiated emissions above 960 MHz from a device operating under 
the provisions of this section shall not exceed the following EIRP 
limits based on measurements using a 1 MHz resolution bandwidth:

------------------------------------------------------------------------
                                                                EIRP in
                       Frequency in MHz                           dBm
------------------------------------------------------------------------
960-1610.....................................................      -75.3
1610-23,120..................................................      -61.3
23,120-23,600................................................      -41.3
23,600-24,000................................................      -61.3
24,000-29,000................................................      -41.3
Above 29,000.................................................     --61.3
------------------------------------------------------------------------

    (3) In addition to the radiated emission limits specified in the 
tables in paragraphs (b)(1) and (b)(2) of this section, transmitters 
operating under the provisions of this section shall not exceed the 
following RMS average EIRP limits when measured using a resolution 
bandwidth of no less than 1 kHz:

------------------------------------------------------------------------
                                                                EIRP in
                       Frequency in MHz                           dBm
------------------------------------------------------------------------
1164-1240....................................................      -85.3
1559-1610....................................................      -85.3
------------------------------------------------------------------------

    (4) There is a limit on the peak level of the emissions contained 
within a 50 MHz bandwidth centered on the frequency at which the highest 
radiated emission occurs and this 50 MHz bandwidth must be contained 
within the 16.2-17.7 GHz band or the 24.05-29.0 GHz

[[Page 826]]

band, as appropriate. The peak EIRP limit is 20 log (RBW/50) dBm where 
RBW is the resolution bandwidth in MHz employed by the measurement 
instrument. RBW shall not be lower than 1 MHz or greater than 50 MHz. 
Further, RBW shall not be greater than the -10 dB bandwidth of the 
device under test. For transmitters that employ frequency hopping, 
stepped frequency or similar modulation types, measurement of the -10 dB 
minimum bandwidth specified in this paragraph shall be made with the 
frequency hop or step function disabled and with the transmitter 
operating continuously at a fundamental frequency. The video bandwidth 
of the measurement instrument shall not be less than RBW. The limit on 
peak emissions applies to the 50 MHz bandwidth centered on the frequency 
at which the highest level radiated emission occurs. If RBW is greater 
than 3 MHz, the application for certification shall contain a detailed 
description of the test procedure, the instrumentation employed in the 
testing, and the calibration of the test setup.
    (5) Radiated emissions at or below 960 MHz shall not exceed the 
emission levels in Sec. 15.209.
    (6) Emissions from digital circuitry used to enable the operation of 
the transmitter may comply with the limits in Sec. 15.209 provided it 
can be clearly demonstrated that those emissions are due solely to 
emissions from digital circuitry contained within the transmitter and 
the emissions are not intended to be radiated from the transmitter's 
antenna. Emissions from associated digital devices, as defined in Sec. 
15.3(k) , e.g., emissions from digital circuitry used to control 
additional functions or capabilities other than the operation of the 
transmitter, are subject to the limits contained in subpart B of this 
part. Emissions from these digital circuits shall not be employed in 
determining the -10 dB bandwidth of the fundamental emission or the 
frequency at which the highest emission level occurs.
    (c) Measurement procedures:
    (1) All emissions at and below 960 MHz are based on measurements 
employing a CISPR quasi-peak detector. Unless otherwise specified, all 
RMS average emission levels specified in this section are to be measured 
utilizing a 1 MHz resolution bandwidth with a one millisecond dwell over 
each 1 MHz segment. The frequency span of the analyzer should equal the 
number of sampling bins times 1 MHz and the sweep rate of the analyzer 
should equal the number of sampling bins times one millisecond. The 
provision in Sec. 15.35(c) that allows emissions to be averaged over a 
100 millisecond period does not apply to devices operating under this 
section. The video bandwidth of the measurement instrument shall not be 
less than the resolution bandwidth and trace averaging shall not be 
employed. The RMS average emission measurement is to be repeated over 
multiple sweeps with the analyzer set for maximum hold until the 
amplitude stabilizes.
    (2) The peak emission measurement is to be repeated over multiple 
sweeps with the analyzer set for maximum hold until the amplitude 
stabilizes.
    (3) For transmitters that employ frequency hopping, stepped 
frequency or similar modulation types, the peak emission level 
measurement, the measurement of the RMS average emission levels, the 
measurement to determine the center frequency, and the measurement to 
determine the frequency at which the highest level emission occurs shall 
be made with the frequency hop or step function active. Gated signals 
may be measured with the gating active. The provisions of Sec. 15.31(c) 
continue to apply to transmitters that employ swept frequency 
modulation.
    (4) The -10 dB bandwidth is based on measurement using a peak 
detector, a 1 MHz resolution bandwidth, and a video bandwidth greater 
than or equal to the resolution bandwidth.
    (5) Alternative measurement procedures may be considered by the 
Commission.

[70 FR 6775, Feb. 9, 2005]




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