47 CFR 90.214 - Transient frequency behavior.

Regulations last checked for updates: May 01, 2025

Title 47 - Telecommunication last revised: Apr 23, 2025

View all text of Subpart I [§ 90.201 - § 90.223]

§ 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:

Time intervals ^{1 2}	Maximum frequency difference ³	All equipment
Time intervals ^{1 2}	Maximum frequency difference ³	150 to 174 MHz	421 to 512 MHz
Transient Frequency Behavior for Equipment Designed to Operate on 25 kHz Channels
t1 ⁴	±25.0 kHz	5.0 ms	10.0 ms
t2	±12.5 kHz	20.0 ms	25.0 ms
t3 ⁴	±25.0 kHz	5.0 ms	10.0 ms
Transient Frequency Behavior for Equipment Designed to Operate on 12.5 kHz Channels
t1 ⁴	±12.5 kHz	5.0 ms	10.0 ms
t2	±6.25 kHz	20.0 ms	25.0 ms
t3 ⁴	±12.5 kHz	5.0 ms	10.0 ms
Transient Frequency Behavior for Equipment Designed to Operate on 6.25 kHz Channels
t1 ⁴	±6.25 kHz	5.0 ms	10.0 ms
t2	±3.125 kHz	20.0 ms	25.0 ms
t3 ⁴	±6.25 kHz	5.0 ms	10.0 ms

¹on is the instant when a 1 kHz test signal is completely suppressed, including any capture time due to phasing.

t1 is the time period immediately following ton.

t2 is the time period immediately following t1.

t3 is the time period from the instant when the transmitter is turned off until toff.

toff is the instant when the 1 kHz test signal starts to rise.

² During the time from the end of t2 to the beginning of t3, the frequency difference must not exceed the limits specified in § 90.213.

³ Difference between the actual transmitter frequency and the assigned transmitter frequency.

⁴ 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]

authority: 47 U.S.C. 154(i), 161, 303(g), 303(r), 332(c)(7), 1401-1473

source: 43 FR 54791, Nov. 22, 1978, unless otherwise noted.

cite as: 47 CFR 90.214