§  15.521   Technical requirements applicable to all UWB devices.

   (a) UWB devices may not be employed for the operation of toys.
   Operation onboard an aircraft, a ship or a satellite is prohibited.

   (b) Manufacturers and users are reminded of the provisions of § §  15.203
   and 15.204.

   (c) Emissions from digital circuitry used to enable the operation of
   the UWB transmitter shall comply with the limits in §  15.209, rather
   than the limits specified in this subpart, provided it can be clearly
   demonstrated that those emissions from the UWB device are due solely to
   emissions from digital circuitry contained within the transmitter and
   that 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 UWB
   transmission, are subject to the limits contained in Subpart B of this
   part.

   (d) Within the tables in § §  15.509, 15.511, 15.513, 15.515, 15.517, and
   15.519, the tighter emission limit applies at the band edges. Radiated
   emission levels at and below 960 MHz are based on measurements
   employing a CISPR quasi-peak detector. Radiated emission levels above
   960 MHz are based on RMS average measurements over a 1 MHz resolution
   bandwidth. The RMS average measurement is based on the use of a
   spectrum analyzer with a resolution bandwidth of 1 MHz, an RMS
   detector, and a 1 millisecond or less averaging time. Unless otherwise
   stated, if pulse gating is employed where the transmitter is quiescent
   for intervals that are long compared to the nominal pulse repetition
   interval, measurements shall be made with the pulse train gated on.
   Alternative measurement procedures may be considered by the Commission.

   (e) The frequency at which the highest radiated emission occurs, fM ,
   must be contained within the UWB bandwidth.

   (f) Imaging systems may be employed only for the type of information
   exchange described in their specific definitions contained in §  15.503.
   The detection of tags or the transfer or data or voice information is
   not permitted under the standards for imaging systems.

   (g) When a peak measurement is required, it is acceptable to use a
   resolution bandwidth other than the 50 MHz specified in this subpart.
   This resolution bandwidth shall not be lower than 1 MHz or greater than
   50 MHz, and the measurement shall be centered on the frequency at which
   the highest radiated emission occurs, fM . If a resolution bandwidth
   other than 50 MHz is employed, the peak EIRP limit shall be 20 log
   (RBW/50) dBm where RBW is the resolution bandwidth in megahertz that is
   employed. This may be converted to a peak field strength level at 3
   meters using E(dBuV/m) = P(dBm EIRP) + 95.2. If RBW is greater than 3
   MHz, the application for certification filed with the Commission must
   contain a detailed description of the test procedure, calibration of
   the test setup, and the instrumentation employed in the testing.

   (h) The highest frequency employed in §  15.33 to determine the
   frequency range over which radiated measurements are made shall be
   based on the center frequency, fC , unless a higher frequency is
   generated within the UWB device. For measuring emission levels, the
   spectrum shall be investigated from the lowest frequency generated in
   the UWB transmitter, without going below 9 kHz, up to the frequency
   range shown in §  15.33(a) or up to fC + 3/(pulse width in seconds),
   whichever is higher. There is no requirement to measure emissions
   beyond 40 GHz provided fC is less than 10 GHz; beyond 100 GHz if fC is
   at or above 10 GHz and below 30 GHz; or beyond 200 GHz if fC is at or
   above 30 GHz.

   (i) The prohibition in §  2.201(f) and 15.5(d) of this chapter against
   Class B (damped wave) emissions does not apply to UWB devices operating
   under this subpart.

   (j) Responsible parties are reminded of the other standards and
   requirements cross referenced in §  15.505, such as a limit on emissions
   conducted onto the AC power lines.

   [ 67 FR 34856 , May 16, 2002, as amended at  68 FR 19751 , Apr. 22, 2003;
    70 FR 6776 , Feb. 9, 2005]

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