Goto Section: 15.255 | 15.257 | Table of Contents
Revised as of September 1, 2021
Goto Year:2020 |
§ 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
(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
(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
(EIRP in dBm measured in
1 MHz) Peak
(EIRP in dBm
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
(GHz) Antenna side
(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
(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
[ 79 FR 12678 , Mar. 6, 2014]
Goto Section: 15.255 | 15.257
Goto Year: 2020 |
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