ANSI/SCTE 18 2018 (ANSI J-STD-42-C)

Emergency Alert Messaging for Cable

This standard defines an Emergency Alert signaling method for use by cable TV systems in the United

States to signal emergencies to digital receiving devices that are offered for retail sale. Such devices

include digital set‐top boxes that are sold to consumers at retail, digital TV receivers, and digital video

recorders.

The Emergency Alert signaling (EAS) scheme defined in this standard allows a cable operator to

disseminate emergency alert information related to state and local‐level emergencies and warnings in

an efficient way, while minimizing disruption to programming. While it is possible for a cable operator to

comply with EAS requirements by simply replacing the source signal for all programs with an emergency

information channel, such switching is disruptive to viewing, is overly intrusive for many kinds of local

warnings and is overly‐complex for the cable operator to implement in a digital cable environment

where each transport stream may carry many programs that would have to be individually interrupted.

Based on the priority level of the alert, the Emergency Alert message may instruct the receiving device

to force‐tune to a designated emergency broadcast channel.