By Jeffrey Krauss,
Emergent Technologist
and President of Telecommunications and Technology Policy
Analog cable systems have traditionally delivered emergency messages by force-tuning the set-top box to one channel that carries the alert message. If you didn't have a set-top box to receive the out-of-band message to change channels, you never got the alert, unless you were watching a broadcast station. Analog broadcast stations overlaid the message as a crawl within the video (and digital TV stations still do that).

But several years ago, it was recognized that a digital cable system could deliver emergency alert messages as a digital bitstream within a digital TV channel. Delivering the message this way means that subscribers without the digital security circuitry or POD module (and thus unable to receive the out-of-band channel) could nonetheless receive emergency alerts. A standardized signaling protocol to do this was developed, and is now published as SCTE 18 2002, Emergency Alert Message for Cable. It can be downloaded from the Web site.

SCTE 18 messages carry the Event Codes listed in Part 11 of the FCC Rules, where the National Emergency Alert System is defined. They also carry the priority level of the alert, and a location code that consists of the state, county and portion of the county affected by the alert. If an alternate video channel is available that carries audio or video information about the alert, the message carries the information that allows the set-top box or digital TV receiver to tune to that channel. Otherwise, the set-top or receiver can display the alert information in the form of scrolling text on the screen.

Even though SCTE technical standards are voluntary, the cable and consumer electronics industries agreed that they would comply with this standard in their December 2002 Memorandum of Understanding on "plug-and-play" cable specifications.

For now, the Event Codes listed in FCC Part 11 are mostly weather-related, like a hurricane warning or flash flood watch. But there are also codes for civil emergency messages and evacuations. In the future, "Amber Alert" messages and other emergency event codes could be added.

This is one of the areas of focus of the FCC's new Media Security & Reliability Council, which consists of representatives of the broadcasting, cable and satellite TV industries. The Council's Web site at provides details. Its Digital Solution Subcommittee has specific responsibility to look at new digital methods for broadcasters to use to deliver emergency alerts. Meanwhile, the Applications Subcommittee of the Advanced Television Systems Committee (ATSC) has undertaken its own investigation of the need for new technical standards for use by broadcasters for delivering digital alert messages to viewers. One of the standards they are considering for possible use by broadcasters is SCTE 18.

Another broadcaster-connected organization called Partnership for Public Warning (PPW) is developing a National Strategy for Integrated Public Warning Policy and Capability. See

Among its goals is defining a standard all-hazard terminology, and creating standards for warning message content and format. But the organization plans to use an XML schema as the basis for its warning message standards, rather than the SCTE standard.

Finally, Thomson, which manufactures RCA-branded TV sets, has developed a product called Alert Guard, which is a National Weather Service radio receiver (162 MHz) built into a TV set. The TV set has colored lights on the panel to signal the level of the alert that is being broadcast (advisory/watch/warning), plus user-selectable audio alerting and on-screen display of the digital text messages that the NWS broadcasts using FSK modulation. There is a menu that allows the user to select the codes for the states and counties to be monitored. According to Thomson, the National Weather Service has received substantial funding in the past year, and its broadcasts now cover 95 percent of the U.S. land area. They are no longer limited to weather alerts, but also now include public safety event codes, Amber Alerts, etc. NOAA retains control over the insertion of non-weather alerts, but they may be originated by other government agencies. Thomson is pitching this as an alternative to the FCC's Emergency Alert System, which relies on broadcasters and cable companies to rebroadcast the NWS alerts.

Consequently, we may be faced with the possibility of "dueling alerts" in an Alert Guard TV set, with broadcaster or cable alerts fighting with NWS alerts for screen space. More seriously, if the NWS broadcasts are now as reliably available as Thomson claims, this suggests a way for small cable systems to avoid the headend costs of supporting the Emergency Alert System. Providing set-top boxes with a built-in capability similar to the Thomson Alert Guard may be just as good as installing headend equipment.

In any case, the traditional analog methods for delivering emergency warning messages will eventually be supplemented or superseded by digital methods. There may be several different pathways for delivering alerts to viewers, using different digital protocols. It's too early to say whether this will lead to redundancy (good) or inconsistency (bad).

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