47 CFR Part 90 covers land mobile radio systems used for mission-critical communication in public safety, business, and industrial sectors. It specifies technical standards for frequency bands like VHF (30–300 MHz), UHF (300–3000 MHz), and 700/800 MHz, setting power limits and emission requirements to avoid interference. Frequency coordination is essential for new systems to prevent conflicts, while rules govern modulation, antenna usage, and co-channel separation.

Part 90 governs the licensing and operation of Private Land Mobile Radio Services (PLMRS), providing rules for public safety, business, and industrial communication systems. It outlines technical standards, frequency allocations, and operational requirements to ensure interference-free communications. Frequency coordination is required to minimize interference, with specific rules for public safety (47 CFR § 90.20), and industrial/business (47 CFR § 90.35).