§ 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]

   return arrow Back to Top