NextGen TV (ATSC 3.0) TxID

TxID Code Assignments for ATSC 3.0 Television Stations

INTRODUCTION

The table in the link below provides TxID code assignments for all licensed full- and low-power TV stations in the U.S. and within the licensing coordination zones in Canada and Mexico. The table will be updated periodically as transmitter moves and new channel assignments are made, as reflected in the FCC Licensing and Management System (LMS) database.


TxID Assignment Table

BACKGROUND

The ATSC 3.0 suite of standards defines an optional Transmitter ID (TxID) code for each individual ATSC 3.0 transmitter, including main transmitters of full-power and low-power stations, as well as TV translators and on-channel low power transmitters that are part of single frequency networks (SFNs). In this online resource, TxID code values are assigned to licensed facilities in blocks, providing each station the resources needed to identify multiple transmitters operating under its single license. Each block of TxID codes is selected to be regionally unique for its channel number.

In the ATSC 3.0 standard, the TxID code is an optional identification capability that may be used by the broadcaster in the ATSC 3.0 Physical Layer transmission to identify individual transmissions for test, measurement, interference identification, and other differentiation purposes. For example, the TxID code may be utilized in the implementation of an SFN. In this case, TxID codes can be used to differentiate otherwise identical physical layer transmissions from one another.

The technical details of the TxID codes are provided in Annex N (beginning on page 245) of ATSC Standard A/322:2022-03, "Physical Layer Protocol," approved 31 March 2022, available at the ATSC website here. The technology utilized is a semi-cloaked, reduced-level injected signal that appears simultaneously or contemporaneously with the transmission of the first Preamble symbol of L1 signaling. It also appears to a receiver not requiring use of the TxID code as just a small amount of additional noise. To improve its signal-to-noise ratio, a TxID code may be repeated multiple times as a sequence "under" the first Preamble symbol, depending on the FFT parameter utilized in the transmitter exciter. It is based on a 13-bit unique code, yielding 8,192 possible numbers that can be used in the identification system. Given the number of licensed stations and number of TxID codes available, TxID codes must be reused multiple times geographically and by channel number in order to assign a sufficient number of TxID codes.

No particular authority or methodology for assigning or registering these identifying codes is suggested by the ATSC 3.0 standard. The TxID code table (link below) is a voluntary register for the TxID transmitter identification system, for which NAB Pilot acts as the registration authority.

TABLE SPECIFICATIONS

The criteria used to develop the table entries are as follows:

Stations should use the first codes in their assigned blocks for their first or main transmitters, and subsequent on-channel transmitters, in the order in which they are identified in the stations' construction permits or licensees (i.e., DTS2, DTS3, etc.) should use the next codes in the assigned TxID code value blocks in sequence. This recommendation is to use the site ID in the FCC authorization to calculate an offset from the first number to assign individual transmitters their unique TxID code values.

This table was developed under the auspices of NAB PILOT by Cavell Mertz & Associates, Inc. and The Merrill Weiss Group.

USE OF THE TABLE

Please contact NAB Pilot at https://nabpilot.org/connect/ for the answers to questions, and/or to provide feedback.

Additional information can be found in the appendix below, which explains how the TxID assignment algorithm works, including a list of assumptions.

The current TxID information can be found in the TxID Assignment Table.


Appendix — Detailed Discussion on Development of TxID Assignments
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