§ 15.256   Operation of level probing radars within the bands 5.925-7.250
GHz, 24.05-29.00 GHz, and 75-85 GHz.

   (a) Operation under this section is limited to level probing radar
   (LPR) devices.

   (b) LPR devices operating under the provisions of this section shall
   utilize a dedicated or integrated transmit antenna, and the system
   shall be installed and maintained to ensure a vertically downward
   orientation of the transmit antenna's main beam.

   (c) LPR devices operating under the provisions of this section shall be
   installed only at fixed locations. The LPR device shall not operate
   while being moved, or while inside a moving container.

   (d) Hand-held applications are prohibited.

   (e) Marketing to residential consumers is prohibited.

   (f) The fundamental bandwidth of an LPR emission is defined as the
   width of the signal between two points, one below and one above the
   center frequency, outside of which all emissions are attenuated by at
   least 10 dB relative to the maximum transmitter output power when
   measured in an equivalent resolution bandwidth.

   (1) The minimum fundamental emission bandwidth shall be 50 MHz for LPR
   operation under the provisions of this section.

   (2) LPR devices operating under this section must confine their
   fundamental emission bandwidth within the 5.925-7.250 GHz, 24.05-29.00
   GHz, and 75-85 GHz bands under all conditions of operation.

   (g) Fundamental emissions limits. (1) All emission limits provided in
   this section are expressed in terms of Equivalent Isotropic Radiated
   Power (EIRP).

   (2) The EIRP level is to be determined from the maximum measured power
   within a specified bandwidth.

   (i) The EIRP in 1 MHz is computed from the maximum power level measured
   within any 1-MHz bandwidth using a power averaging detector;

   (ii) The EIRP in 50 MHz is computed from the maximum power level
   measured with a peak detector in a 50-MHz bandwidth centered on the
   frequency at which the maximum average power level is realized and this
   50 MHz bandwidth must be contained within the authorized operating
   bandwidth. For a RBW less than 50 MHz, the peak EIRP limit (in dBm) is
   reduced by 20 log(RBW/50) dB where RBW is the resolution bandwidth in
   megahertz. The RBW shall not be lower than 1 MHz or greater than 50
   MHz. The video bandwidth of the measurement instrument shall not be
   less than the RBW. If the RBW is greater than 3 MHz, the application
   for certification filed shall contain a detailed description of the
   test procedure, calibration of the test setup, and the instrumentation
   employed in the testing.

   (3) The EIRP limits for LPR operations in the bands authorized by this
   rule section are provided in Table 1. The emission limits in Table 1
   are based on boresight measurements (i.e., measurements performed
   within the main beam of an LPR antenna).

   Table 1--LPR EIRP Emission Limits
   Frequency band of operation
   (GHz) Average
   emission limit
   (EIRP in dBm measured in
   1 MHz) Peak
   emission limit
   (EIRP in dBm
   measured in
   50 MHz)
          5.925-7.250                -33  7
          24.05-29.00                -14 26
          75-85                       -3 34

   (h) Unwanted emissions limits. Unwanted emissions from LPR devices
   shall not exceed the general emission limit in § 15.209 of this
   chapter.

   (i) Antenna beamwidth. (A) LPR devices operating under the provisions
   of this section within the 5.925-7.250 GHz and 24.05-29.00 GHz bands
   must use an antenna with a -3 dB beamwidth no greater than 12 degrees.

   (B) LPR devices operating under the provisions of this section within
   the 75-85 GHz band must use an antenna with a -3 dB beamwidth no
   greater than 8 degrees.

   (j) Antenna side lobe gain. LPR devices operating under the provisions
   of this section must limit the side lobe antenna gain relative to the
   main beam gain for off-axis angles from the main beam of greater than
   60 degrees to the levels provided in Table 2.

   Table 2--Antenna Side Lobe Gain Limits
   Frequency range
   (GHz) Antenna side
   lobe gain
   limit relative
   to main
   beam gain
   (dB)
         5.925-7.250    -22
         24.05-29.00    -27
         75-85          -38

   (k) Emissions from digital circuitry used to enable the operation of
   the transmitter may comply with the limits in § 15.209 of this chapter
   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) of this part, 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, part 15 of this chapter. 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.

   (l) Measurement procedures. (1) Radiated measurements of the
   fundamental emission bandwidth and power shall be made with maximum
   main-beam coupling between the LPR and test antennas (boresight).

   (2) Measurements of the unwanted emissions radiating from an LPR shall
   be made utilizing elevation and azimuth scans to determine the location
   at which the emissions are maximized.

   (3) All emissions at and below 1,000 MHz except 9-90 kHz and 110-490
   kHz bands are based on measurements employing a CISPR quasi-peak
   detector.

   (4) The fundamental emission bandwidth measurement shall be made using
   a peak detector with a resolution bandwidth of 1 MHz and a video
   bandwidth of at least 3 MHz.

   (5) The provisions in § 15.35(b) and (c) of this part that require
   emissions to be averaged over a 100 millisecond period and that limits
   the peak power to 20 dB above the average limit do not apply to devices
   operating under paragraphs (a) through (l) of this section.

   (6) Compliance measurements for minimum emission bandwidth of
   frequency-agile LPR devices shall be performed with any related
   frequency sweep, step, or hop function activated.

   (7) Compliance measurements shall be made in accordance with the
   specific procedures published or otherwise authorized by the
   Commission.

   [ 79 FR 12678 , Mar. 6, 2014]

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