47 CFR § 90.535 - Modulation and spectrum usage efficiency requirements.

---
identifier: "/us/cfr/t47/s90.535"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "47 CFR § 90.535 - Modulation and spectrum usage efficiency requirements."
title_number: 47
title_name: "Telecommunication"
section_number: "90.535"
section_name: "Modulation and spectrum usage efficiency requirements."
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: "2026-04-05"
last_updated: "2026-04-05"
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"
---


# 90.535 Modulation and spectrum usage efficiency requirements.

Transmitters designed to operate in 769-775 MHz and 799-805 MHz frequency bands must meet the following modulation standards:

(a) All transmitters in the 769-775 MHz and 799-805 MHz frequency bands must use digital modulation. Mobile and portable transmitters may have analog modulation capability only as a secondary mode in addition to its primary digital mode except on the interoperability channels listed in § 90.531(b)(1). Analog modulation is prohibited on the interoperability channels. Mobile and portable transmitters that only operate on the low power channels designated in § 90.531(b)(3) and (4) are exempt from this digital modulation requirement.

(b) Transmitters designed to operate in the narrowband segment using digital modulation must be capable of maintaining a minimum data (non-voice) rate of 4.8 kbps per 6.25 kHz of bandwidth.

(c) Transmitters designed to operate in the wideband segment using digital modulation must be capable of maintaining a minimum data (non-voice) rate of 384 kbps per 150 kHz of bandwidth.

(d) Transmitters designed to operate on the channels listed in paragraphs (b)(2), (5), (6), and (7) of § 90.531 must be capable of operating in the voice mode at an efficiency of at least one voice path per 12.5 kHz of spectrum bandwidth.

[63 FR 58651, Nov. 2, 1998, as amended at 65 FR 53645, Sept. 5, 2000; 65 FR 66655, Nov. 7, 2000; 67 FR 76701, Dec. 13, 2002; 70 FR 21673, Apr. 27, 2005; 72 FR 48861, Aug. 24, 2007; 79 FR 71326, Dec. 2, 2014; 81 FR 66833, Sept. 29, 2016]