(a) The carrier frequency of each transmitter authorized in these services must be maintained within the following percentage of the reference frequency except as otherwise provided in paragraph (b) of this section or in the applicable subpart of this part (unless otherwise specified in the instrument of station authorization the reference frequency will be deemed to be the assigned frequency):
| Frequency (MHz) | Frequency tolerance (percent) |
|---|---|
| 928 to 9295 | 0.0005 |
| 932 to 932.5 | 0.00015 |
| 932.5 to 935 | 0.00025 |
| 941 to 941.5 | 0.00015 |
| 941.5 to 944 | 0.00025 |
| 952 to 9605 | 0.0005 |
| 1,850 to 1,990 | 0.002 |
| 2,110 to 2,200 | 0.001 |
| 2,450 to 2,5001 | 0.001 |
| 3,700 to 4,2001 | 0.005 |
| 5,925 to 6,8751 | 0.005 |
| 6,875 to 7,1251 | 0.005 |
| 10,550 to 11,7001 2 | 0.005 |
| 11,700 to 12,2001 | 0.005 |
| 12,200 to 13,2504 | 0.005 |
| 14,200 to 14,400 | 0.03 |
| 17,700 to 18,8203 | 0.003 |
| 18,820 to 18,9203 | 0.001 |
| 928 to 9295 | 0.0005 |
| 18,920 to 19,7003 | 0.003 |
| 19,700 to 27,5004 7 | 0.001 |
| 29,100 to 29,250 | 0.001 |
| 31,000 to 31,3006 | 0.001 |
| 31,300 to 40,0004 | 0.03 |
| 71,000 to 76,0008 | |
| 81,000 to 86,0008 | |
| 92,000 to 95,0008 |
1Applicable only to common carrier LTTS stations. Tolerance for 2450-2500 MHz is 0.005%. Beginning Aug. 9, 1975, this tolerance will govern the marketing of LTTS equipment and the issuance of all such authorizations for new radio equipment. Until that date new equipment may be authorized with a frequency tolerance of .03% in the frequency range 2,200 to 10,500 MHz and .05% in the range 10,500 MHz to 12,200 MHz, and equipment so authorized may continue to be used for its life provided that it does not cause interference to the operation of any other licensee. Beginning March 1, 2005, new LTTS operators will not be licensed and existing LTTS licensees will not be renewed in the 11.7-12.2 GHz band.
2See subpart G of this part for the stability requirements for transmitters used in the Digital Electronic Message Service.
3Existing type accepted equipment with a frequency tolerance of ±0.03% may be marketed until December 1, 1988. Equipment installed and operated prior to December 1, 1988 may continue to operate after that date with a minimum frequency tolerance of ±0.03%. However, the replacement of equipment requires that the current tolerance be met.
4Applicable to private operational fixed point-to-point microwave and stations providing MVDDS.
5For private operational fixed point-to-point microwave systems, with a channel greater than or equal to 50 KHz bandwidth, ±0.0005%; for multiple address master stations, regardless of bandwidth, ±0.00015%; for multiple address remote stations with 12.5 KHz bandwidths, ±0.00015%; for multiple address remote stations with channels greater than 12.5 KHz bandwidth, ±0.0005%.
6For stations authorized prior to March 11, 1997, transmitter tolerance shall not exceed 0.03%.
7The frequency tolerance for stations authorized on or before April 1, 2005 is 0.03%. Existing licensees and pending applicants on that date may continue to operate after that date with a frequency tolerance of 0.03%, provided that it does not cause harmful interference to the operation of any other licensee. For analog systems, if the channel bandwidth is greater than 30 MHz up to 50 MHz, the frequency tolerance standard will be 0.03%; if the channel bandwidth is 30 MHz or less, then the frequency tolerance standard will be 0.003%. This analog standard is conditional provided that harmful interference is not caused to digital stations operating within the 0.001% tolerance standards. If harmful interference is caused to stations operating with the more stringent standard, the onus shall be on the operators with the less stringent parameters to develop an engineering solution to the problem. For exceptions, see §101.147 and §101.507.
8Equipment authorized to be operated in the 71,000-76,000 MHz, 81,000-86,000 MHz, 92,000-94,000 MHz and 94,100-95,000 MHz bands is exempt from the frequency tolerance requirement noted in the table of paragraph (a) of this section.
(b) Heterodyne microwave radio systems may be authorized at a somewhat less restrictive frequency tolerance (up to .01 percent) to compensate for frequency shift caused by numerous repeaters between base band signal insertion. Where such relaxation is sought, applicant must provide all calculations and indicate the desired tolerance over each path. In such instances the radio transmitters and receivers used must individually be capable of complying with the tolerance specified in paragraph (a) of this section. Heterodyne operation is restricted to channel bandwidth of 10 MHz or greater.
(c) As an additional requirement in any band where the Commission makes assignments according to a specified channel plan, provisions must be made to prevent the emission included within the occupied bandwidth from radiating outside the assigned channel at a level greater than that specified in §101.111.
[61 FR 26677, May 28, 1996, as amended at 62 FR 23167, Apr. 29, 1997; 63 FR 6105, Feb. 6, 1998; 63 FR 9448, Feb. 25, 1998; 63 FR 14039, Mar. 24, 1998; 63 FR 36611, July 7, 1998; 66 FR 35110, July 3, 2001; 67 FR 43038, June 26, 2002; 68 FR 4956, Jan. 31, 2003; 69 FR 3266, Jan. 23, 2004; 69 FR 16832, Mar. 31, 2004; 70 FR 4787, Jan. 31, 2005; 76 FR 59572, Sept. 27, 2011; 81 FR 79945, Nov. 14, 2016]
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