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
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.