#### § 90.213 Frequency stability.

(a) Unless noted elsewhere, transmitters used in the services governed by this part must have a minimum frequency stability as specified in the following table.

Table 1 to [§ 90.213](/on/2024-09-20/title-47/section-90.213)(a)—Minimum Frequency Stability

[Parts per million (ppm)]

| Frequency range (MHz) | Fixed and base stations | Mobile stations | |
| --- | --- | --- | --- |
| Over 2 watts output power | 2 watts or less output power |
| Below 25 | 1 2 3 100 | 100 | 200 |
| 25-50 | 20 | 20 | 50 |
| 72-76 | 5 | | 50 |
| 150-174 | 5 11 5 | 6 5 | 4 6 50 |
| 216-220 | 1.0 | | 1.0 |
| 220-22212 | 0.1 | 1.5 | 1.5 |
| 421-512 | 7 11 14 2.5 | 8 5 | 8 5 |
| 806-809 | 14 1.0 | 1.5 | 1.5 |
| 809-824 | 14 1.5 | 2.5 | 2.5 |
| 851-854 | 1.0 | 1.5 | 1.5 |
| 854-869 | 1.5 | 2.5 | 2.5 |
| 896-901 | 14 0.1 | 1.5 | 1.5 |
| 902-928 | 2.5 | 2.5 | 2.5 |
| 902-92813 | 2.5 | 2.5 | 2.5 |
| 929-930 | 1.5 | | |
| 935-940 | 0.1 | 1.5 | 1.5 |
| 1427-1435 | 9 300 | 300 | 300 |
| Above 245010 | | | |
| | | | |
| --- | --- | --- | --- |
| 1 Fixed and base stations with over 200 watts transmitter power must have a frequency stability of 50 ppm except for equipment used in the Public Safety Pool where the frequency stability is 100 ppm. | | | |
| 2 For single sideband operations below 25 MHz, the carrier frequency must be maintained within 50 Hz of the authorized carrier frequency. | | | |
| 3 Travelers information station transmitters operating from 530-1700 kHz and transmitters exceeding 200 watts peak envelope power used for disaster communications and long distance circuit operations pursuant to [§§ 90.242](/on/2024-09-20/title-47/section-90.242) and [90.264](/on/2024-09-20/title-47/section-90.264) must maintain the carrier frequency to within 20 Hz of the authorized frequency. | | | |
| 4 Stations operating in the 154.45 to 154.49 MHz or the 173.2 to 173.4 MHz bands must have a frequency stability of 5 ppm. | | | |
| 5 In the 150-174 MHz band, fixed and base stations with a 12.5 kHz channel bandwidth must have a frequency stability of 2.5 ppm. Fixed and base stations with a 6.25 kHz channel bandwidth must have a frequency stability of 1.0 ppm. | | | |
| 6 In the 150-174 MHz band, mobile stations designed to operate with a 12.5 kHz channel bandwidth or designed to operate on a frequency specifically designated for itinerant use or designed for low-power operation of two watts or less, must have a frequency stability of 5.0 ppm. Mobile stations designed to operate with a 6.25 kHz channel bandwidth must have a frequency stability of 2.0 ppm. | | | |
| 7 In the 421-512 MHz band, fixed and base stations with a 12.5 kHz channel bandwidth must have a frequency stability of 1.5 ppm. Fixed and base stations with a 6.25 kHz channel bandwidth must have a frequency stability of 0.5 ppm. | | | |
| 8 In the 421-512 MHz band, mobile stations designed to operate with a 12.5 kHz channel bandwidth must have a frequency stability of 2.5 ppm. Mobile stations designed to operate with a 6.25 kHz channel bandwidth must have a frequency stability of 1.0 ppm. | | | |
| 9 Fixed stations with output powers above 120 watts and necessary bandwidth less than 3 kHz must operate with a frequency stability of 100 ppm. Fixed stations with output powers less than 120 watts and using time-division multiplex, must operate with a frequency stability of 500 ppm. | | | |
| 10 Frequency stability for DSRCS equipment in the 5895-5925 MHz band is specified in [subpart M of this part](/on/2024-09-20/title-47/part-90/subpart-M). For all other equipment, frequency stability is to be specified in the station authorization. | | | |
| 11 Paging transmitters operating on paging-only frequencies must operate with frequency stability of 5 ppm in the 150-174 MHz band and 2.5 ppm in the 421-512 MHz band. | | | |
| 12 Mobile units may utilize synchronizing signals from associated base stations to achieve the specified carrier stability. | | | |
| 13 Fixed non-multilateration transmitters with an authorized bandwidth that is more than 40 kHz from the band edge, intermittently operated hand-held readers, and mobile transponders are not subject to frequency tolerance restrictions. | | | |
| 14 Control stations may operate with the frequency tolerance specified for associated mobile frequencies. | | | |

(b) For the purpose of determining the frequency stability limits, the power of a transmitter is considered to be the maximum rated output power as specified by the manufacturer.

[[60 FR 37266](https://www.federalregister.gov/citation/60-FR-37266), July 19, 1995, as amended at [61 FR 4235](https://www.federalregister.gov/citation/61-FR-4235), Feb. 5, 1996; [61 FR 18986](https://www.federalregister.gov/citation/61-FR-18986), Apr. 30, 1996; [61 FR 38403](https://www.federalregister.gov/citation/61-FR-38403), July 24, 1996; [62 FR 2040](https://www.federalregister.gov/citation/62-FR-2040), Jan. 15, 1997; [62 FR 18927](https://www.federalregister.gov/citation/62-FR-18927), Apr. 17, 1997; [67 FR 41860](https://www.federalregister.gov/citation/67-FR-41860), June 20, 2002; [69 FR 46443](https://www.federalregister.gov/citation/69-FR-46443), Aug. 3, 2004; [69 FR 67838](https://www.federalregister.gov/citation/69-FR-67838), Nov. 22, 2004; [85 FR 43139](https://www.federalregister.gov/citation/85-FR-43139), July 15, 2020; [86 FR 23297](https://www.federalregister.gov/citation/86-FR-23297), May 3, 2021]

###### Editorial Note

#### Editorial Note:

At [85 FR 43139](https://www.federalregister.gov/citation/85-FR-43139), July 16, 2020, [§ 90.213](/on/2024-09-20/title-47/section-90.213) was amended in the table by adding entries in numerical order for “896-901” and “935-940”, however due to an inaccurate amendatory instruction, this amendment could not be incorporated.