47 CFR § 90.669 - Emission limits.

---
identifier: "/us/cfr/t47/s90.669"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "47 CFR § 90.669 - Emission limits."
title_number: 47
title_name: "Telecommunication"
section_number: "90.669"
section_name: "Emission 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"
---


# 90.669 Emission limits.

(a) On any frequency in an MTA licensee's spectrum block that is adjacent to a non-MTA frequency, the power of any emission shall be attenuated below the transmitter power (P) by at least 43 plus 10 log<sub>10</sub>(P) decibels or 80 decibels, whichever is the lesser attenuation.

The measurements of emission power can be expressed in peak or average values, provided they are expressed in the same parameters as the transmitter power.

(b) When an emission outside of the authorized bandwidth causes harmful interference, the Commission may, at its discretion, require greater attenuation than specified in this section.

[60 FR 21992, May 4, 1995]