§ 90.1215   Power limits.

   The transmitting power of stations operating in the 4940-4990 MHz band
   must not exceed the maximum limits in this section.

   (a)(1) The maximum conducted output power should not exceed:
   Channel bandwidth (MHz) Low power
   maximum conducted
   output power (dBm) High power maximum
   conducted output
   power (dBm)
   1 7 20
   5 14 27
   10 17 30
   15 18.8 31.8
   20 20 33

   (2) High power devices are also limited to a peak power spectral
   density of 21 dBm per one MHz. High power devices using channel
   bandwidths other than those listed above are permitted; however, they
   are limited to peak power spectral density of 21 dBm/MHz. If
   transmitting antennas of directional gain greater than 9 dBi are used,
   both the maximum conducted output power and the peak power spectral
   density should be reduced by the amount in decibels that the
   directional gain of the antenna exceeds 9 dBi. However, high power
   point-to-point and point-to-multipoint operations (both fixed and
   temporary-fixed rapid deployment) may employ transmitting antennas with
   directional gain up to 26 dBi without any corresponding reduction in
   the maximum conducted output power or spectral density. Corresponding
   reduction in the maximum conducted output power and peak power spectral
   density should be the amount in decibels that the directional gain of
   the antenna exceeds 26 dBi.

   (b) Low power devices are also limited to a peak power spectral density
   of 8 dBm per one MHz. Low power devices using channel bandwidths other
   than those listed above are permitted; however, they are limited to a
   peak power spectral density of 8 dBm/MHz. If transmitting antennas of
   directional gain greater than 9 dBi are used, both the maximum
   conducted output power and the peak power spectral density should be
   reduced by the amount in decibels that the directional gain of the
   antenna exceeds 9 dBi.

   (c) The maximum conducted output power is measured as a conducted
   emission over any interval of continuous transmission using
   instrumentation calibrated in terms of an RMS-equivalent voltage. If
   the device cannot be connected directly, alternative techniques
   acceptable to the Commission may be used. The measurement results shall
   be properly adjusted for any instrument limitations, such as detector
   response times, limited resolution bandwidth capability when compared
   to the emission bandwidth, sensitivity, etc., so as to obtain a true
   maximum conducted output power measurement conforming to the
   definitions in this paragraph for the emission in question.

   (d) The peak power spectral density is measured as conducted emission
   by direct connection of a calibrated test instrument to the equipment
   under test. If the device cannot be connected directly, alternative
   techniques acceptable to the Commission may be used. Measurements are
   made over a bandwidth of one MHz or the 26 dB emission bandwidth of the
   device, whichever is less. A resolution bandwidth less than the
   measurement bandwidth can be used, provided that the measured power is
   integrated to show total power over the measurement bandwidth. If the
   resolution bandwidth is approximately equal to the measurement
   bandwidth, and much less than the emission bandwidth of the equipment
   under test, the measured results shall be corrected to account for any
   difference between the resolution bandwidth of the test instrument and
   its actual noise bandwidth.

   (e) The ratio of the peak excursion of the modulation envelope
   (measured using a peak hold function) to the maximum conducted output
   power shall not exceed 13 dB across any 1 MHz bandwidth or the emission
   bandwidth whichever is less.

   [ 70 FR 28467 , May 18, 2005, as amended at  74 FR 23803 , May 21, 2009;  74 FR 27455 , June 10, 2009]

   return arrow Back to Top