47 CFR § 90.221 - Adjacent channel power limits.
---
identifier: "/us/cfr/t47/s90.221"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "47 CFR § 90.221 - Adjacent channel power limits."
title_number: 47
title_name: "Telecommunication"
section_number: "90.221"
section_name: "Adjacent channel power limits."
chapter_name: "FEDERAL COMMUNICATIONS COMMISSION"
subchapter_number: "D"
subchapter_name: "SAFETY AND SPECIAL RADIO SERVICES"
part_number: "90"
part_name: "PRIVATE LAND MOBILE RADIO SERVICES"
positive_law: false
currency: "2026-03-24"
last_updated: "2026-03-24"
format_version: "1.1.0"
generator: "[email protected]"
authority: "47 U.S.C. 154(i), 161, 303(g), 303(r), 332(c)(7), 1401-1473"
regulatory_source: "43 FR 54791, Nov. 22, 1978, unless otherwise noted."
cfr_part: "90"
---
# 90.221 Adjacent channel power limits.
(a) For the frequency bands indicated below, operations using equipment designed to operate with a 25 kHz channel bandwidth may be authorized up to a 22 kHz bandwidth if the equipment meets the adjacent channel power (ACP) limits below. The table specifies a value for the ACP as a function of the displacement from the channel center frequency and a measurement bandwidth of 18 kHz.
(b)(1) Maximum adjacent power levels for frequencies in the 450-470 MHz band:
| Frequency offset | Maximum ACP (dBc) for devices 1 watt and less | Maximum ACP (dBc) for devices above 1 watt |
| --- | --- | --- |
| 25 kHz | −55 dBc | −60 dBc |
| 50 kHz | −70 dBc | −70 dBc |
| 75 kHz | −70 dBc | −70 dBc |
(2) In any case, no requirement in excess of −36 dBm shall apply.
(c)(1) Maximum adjacent power levels for frequencies in the 809-824/854-869 MHz band:
| Frequency offset | Maximum ACP (dBc) for devices less than 15 watts | Maximum ACP (dBc) for devices 15 watts and above |
| --- | --- | --- |
| 25 kHz | −55 dBc | −55 dBc |
| 50 kHz | −65 dBc | −65 dBc |
| 75 kHz | −65 dBc | −70 dBc |
(2) In any case, no requirement in excess of −36 dBm shall apply.
(d) On any frequency removed from the assigned frequency by more than 75 kHz, the attenuation of any emission must be at least 43 + 10 log (P<sub>watts</sub>) dB.
[77 FR 61538, Oct. 10, 2012]