47 CFR § 90.214 - Transient frequency behavior.
---
identifier: "/us/cfr/t47/s90.214"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "47 CFR § 90.214 - Transient frequency behavior."
title_number: 47
title_name: "Telecommunication"
section_number: "90.214"
section_name: "Transient frequency behavior."
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"
---
# 90.214 Transient frequency behavior.
Transmitters designed to operate in the 150-174 MHz and 421-512 MHz frequency bands must maintain transient frequencies within the maximum frequency difference limits during the time intervals indicated:
| | | | |
| --- | --- | --- | --- |
| Transient Frequency Behavior for Equipment Designed to Operate on 25 kHz Channels | | | |
| t | ±25.0 kHz | 5.0 ms | 10.0 ms |
| t | ±12.5 kHz | 20.0 ms | 25.0 ms |
| t | ±25.0 kHz | 5.0 ms | 10.0 ms |
| Transient Frequency Behavior for Equipment Designed to Operate on 12.5 kHz Channels | | | |
| t | ±12.5 kHz | 5.0 ms | 10.0 ms |
| t | ±6.25 kHz | 20.0 ms | 25.0 ms |
| t | ±12.5 kHz | 5.0 ms | 10.0 ms |
| Transient Frequency Behavior for Equipment Designed to Operate on 6.25 kHz Channels | | | |
| t | ±6.25 kHz | 5.0 ms | 10.0 ms |
| t | ±3.125 kHz | 20.0 ms | 25.0 ms |
| t | ±6.25 kHz | 5.0 ms | 10.0 ms |
| is the instant when a 1 kHz test signal is completely suppressed, including any capture time due to phasing. | | | |
| t is the time period immediately following t. | | | |
| t is the time period immediately following t. | | | |
| t is the time period from the instant when the transmitter is turned off until t. | | | |
| t is the instant when the 1 kHz test signal starts to rise. | | | |
| During the time from the end of t to the beginning of t, the frequency difference must not exceed the limits specified in § 90.213. | | | |
| Difference between the actual transmitter frequency and the assigned transmitter frequency. | | | |
| If the transmitter carrier output power rating is 6 watts or less, the frequency difference during this time period may exceed the maximum frequency difference for this time period. | | | |
[62 FR 2040, Jan. 15, 1997]