#### § 73.626 TV distributed transmission systems.

(a) *Distributed transmission systems.* A TV station may be authorized to operate multiple synchronized transmitters on its assigned channel to provide service consistent with the requirements of this section. Such operation is called a distributed transmission system (DTS). Except as expressly provided in this section, TV stations operating a DTS facility must comply with all rules applicable to TV single-transmitter stations.

(b) *Authorized service area.* For purposes of compliance with this section, a station's “authorized service area” is defined as the area within its predicted noise-limited service contour determined using the facilities authorized for the station in a license or construction permit for non-DTS, single-transmitter-location operation (its “authorized facility”).

(c) *Table of Distances.* The following Table of Distances describes (by channel and zone) a station's maximum service area that can be obtained in applying for a DTS authorization and the maximum interference area that can be created by its facilities.

Table 1 to Paragraph (c)

| Channel | Zone | Service field strength (dBu) | Distance from reference point | | Reference interference field strength (dBu) | Distance from reference point F(50,10) (km) | Node interfering field strength F(50,10) (dBu) |
| --- | --- | --- | --- | --- | --- | --- | --- |
| F(50,90) (km) | F(50,50) (km) |
| 2-6 | 1 | 28 | 108 | 132 | 28 | 183 | 18.8 |
| 2-6 | 2 and 3 | 28 | 128 | 158 | 28 | 209 | 18.8 |
| 7-13 | 1 | 36 | 101 | 121 | 33 | 182 | 23.8 |
| 7-13 | 2 and 3 | 36 | 123 | 149 | 33 | 208 | 23.8 |
| 14-36 | 1, 2, and 3 | 41 | 103 | 142 | 36 | 246 | 26.8 |

(1) TV station zones are defined in [§ 73.609](/on/2024-09-20/title-47/section-73.609).

(2) *DTS reference point.* A station's DTS reference point is established in the FCC Order that created or made final modifications to the Table of TV Allotments, [§ 73.622(j)](/on/2024-09-20/title-47/section-73.622#p-73.622(j)), and the corresponding facilities for the station's channel assignment as set forth in that FCC Order.

(d) *Determining DTS coverage.* The coverage for each DTS transmitter is determined based on the F(50,90) field strength given in the Table of Distances (in [paragraph (c)](/on/2024-09-20/title-47/section-73.626#p-73.626(c)) of this section), calculated in accordance with [§ 73.619(b)](/on/2024-09-20/title-47/section-73.619#p-73.619(b)). The combined coverage of a DTS station is the logical union of the coverage of all DTS transmitters.

(e) *DTS protection from interference.* A DTS station must be protected from interference in accordance with the criteria specified in [§ 73.620](/on/2024-09-20/title-47/section-73.620). To determine compliance with the interference protection requirements of [§ 73.620](/on/2024-09-20/title-47/section-73.620), the population served by a DTS station shall be the population within the station's combined coverage contour, excluding the population in areas that are outside both the TV station's authorized service area and the Table of Distances area (in [paragraph (c)](/on/2024-09-20/title-47/section-73.626#p-73.626(c)) of this section). Only population that is predicted to receive service by the method described in [§ 73.619(c)(2)](/on/2024-09-20/title-47/section-73.619#p-73.619(c)(2)) from at least one individual DTS transmitter will be considered.

(f) *Applications for DTS.* An application proposing use of a DTS will not be accepted for filing unless it meets all of the following conditions:

(1) The combined coverage from all of the DTS transmitters covers all of the applicant's authorized service area;

(2) Each DTS transmitter's coverage is contained within either the TV station's Table of Distances area (pursuant to [paragraph (c)](/on/2024-09-20/title-47/section-73.626#p-73.626(c)) of this section) or its authorized service area, except where such extension of coverage meets the following criteria:

(i) In no event shall the F(50,50) service contour of any DTS transmitter extend beyond that of its authorized facility and its Table of Distances F(50,50) area; and

(ii) In no event shall the F(50,10) node-interfering contour of any DTS transmitter, aside from one located at the site of its authorized facility, extend beyond the F(50,10) reference-interfering contour of its authorized facility and its Table of Distances F(50,10) reference area; and

(iii) In no event shall the F(50,10) reference-interfering contour of a facility located at the site of its authorized facility extend beyond the F(50,10) reference-interfering contour of its authorized facility;

(3) Each DTS transmitter's coverage is contiguous with at least one other DTS transmitter's coverage;

(4) The coverage from one or more DTS transmitter(s) is shown to provide principal community coverage as required in [§ 73.618](/on/2024-09-20/title-47/section-73.618);

(5) The “combined field strength” of all the DTS transmitters in a network does not cause interference to another station in excess of the criteria specified in [§ 73.620](/on/2024-09-20/title-47/section-73.620), where the combined field strength level is determined by a “root-sum-square” calculation, in which the combined field strength level at a given location is equal to the square root of the sum of the squared field strengths from each transmitter in the DTS network at that location.

(6) Each DTS transmitter must be located within either the TV station's Table of Distances area or its authorized service area.

(g) All transmitters operating under a single DTS license must follow the same digital broadcast television transmission standard.

[[73 FR 74063](https://www.federalregister.gov/citation/73-FR-74063), Dec. 5, 2008, as amended at [83 FR 5022](https://www.federalregister.gov/citation/83-FR-5022), Feb. 2, 2018; [86 FR 21226](https://www.federalregister.gov/citation/86-FR-21226), Apr. 22, 2021; [89 FR 7250](https://www.federalregister.gov/citation/89-FR-7250), Feb. 1, 2024]