§  90.672   Unacceptable interference to non-cellular 800 MHz licensees from
800 MHz cellular systems or part 22 Cellular Radiotelephone systems, and
within the 900 MHz narrowband segments, and to narrowband 900 MHz licensees
from 900 MHz broadband licensees.

   (a) Definition. Except as provided in 47 CFR 90.617(k), unacceptable
   interference to non-cellular licensees in the 800 MHz band from 800 MHz
   cellular systems or part 22 of this chapter, Cellular Radiotelephone
   systems; unacceptable interference within the 900 MHz narrowband
   segment; and unacceptable interference to narrowband 900 MHz licensees
   from 900 MHz broadband licensees, will be deemed to occur when the
   below conditions are met:

   (1) A transceiver at a site at which interference is encountered:

   (i) Is in good repair and operating condition, and is receiving:

   (A) From the 800 MHz band, a median desired signal strength of −104 dBm
   or higher if operating in the 800 MHz band, or a median desired signal
   strength of −88 dBm if operating in the 900 MHz narrowband segment, as
   measured at the R.F. input of the receiver of a mobile unit; or

   (B) From the 800 MHz band, a median desired signal strength of −101 dBm
   or higher if operating in the 800 MHz band, or a median desired signal
   strength of −85 dBm if operating in the 900 MHz narrowband segment; or,
   as measured at the R.F. input of the receiver of a portable i.e.,
   hand-held unit;

   (C) From the 900 MHz broadband segment, a median desired signal
   strength of −104 dBm or higher if operating in the 900 MHz narrowband
   segment, as measured at the R.F. input of the receiver of a mobile
   unit; or

   (D) From the 900 MHz broadband segment, median desired signal strength
   of −101 dBm or higher if operating in the 900 MHz narrowband segment,
   as measured at the R.F. input of the receiver of a portable, i.e.,
   hand-held unit; and either

   (ii) Is a voice transceiver:

   (A) With manufacturer published performance specifications for the
   receiver section of the transceiver equal to, or exceeding, the minimum
   standards set out in paragraph (b) of this section, and;

   (B) Receiving an undesired signal or signals which cause the measured
   Carrier to Noise plus Interference (C/(I + N)) ratio of the receiver
   section of said transceiver to be less than 20 dB if operating in the
   800 MHz band, or less than 17 dB if operating in the 900 MHz narrowband
   segment, or;

   (iii) Is a non-voice transceiver receiving an undesired signal or
   signals which cause the measured bit error rate (BER) (or some
   comparable specification) of the receiver section of said transceiver
   to be more than the value reasonably designated by the manufacturer.

   (2) Provided, however, that if the receiver section of the mobile or
   portable voice transceiver does not conform to the standards set out in
   paragraph (b) of this section, then that transceiver shall be deemed
   subject to unacceptable interference only at sites where the median
   desired signal satisfies the applicable threshold measured signal power
   in paragraph (a)(1)(i) of this section after an upward adjustment to
   account for the difference in receiver section performance. The upward
   adjustment shall be equal to the increase in the desired signal
   required to restore the receiver section of the subject transceiver to
   the 20 dB C/(I + N) ratio of paragraph (a)(1)(ii)(B) of this section.
   The adjusted threshold levels shall then define the minimum measured
   signal power(s) in lieu of paragraph (a)(1)(i) of this section at which
   the licensee using such non-compliant transceiver is entitled to
   interference protection.

   (b) Minimum receiver requirements. Voice transceivers capable of
   operating in the 806-824 MHz portion of the 800 MHz band, or in the 900
   MHz narrowband segment, shall have the following minimum performance
   specifications in order for the system in which such transceivers are
   used to claim entitlement to full protection against unacceptable
   interference. (See paragraph (a)(2) of this section.)

   (1) Voice units intended for mobile use: 75 dB intermodulation
   rejection ratio; 75 dB adjacent channel rejection ratio; −116 dBm
   reference sensitivity.

   (2) Voice units intended for portable use: 70 dB intermodulation
   rejection ratio; 70 dB adjacent channel rejection ratio; −116 dBm
   reference sensitivity.

   (3) Voice units intended for mobile or portable use in the 900 MHz
   narrowband segment: 60 dB intermodulation rejection ratio; 60 dB
   adjacent channel rejection ratio; −116 dBm reference sensitivity.

   [ 85 FR 43141 , July 15, 2020]