§ 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 § 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:
   Frequency in MHz EIRP in 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:
   Frequency in MHz EIRP in 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:
   Frequency in MHz EIRP in 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 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 § 15.209.

   (6) Emissions from digital circuitry used to enable the operation of the
   transmitter may comply with the limits in § 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 § 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
   § 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 § 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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