I do not have any information on the subject, but I
> wonder in what way Amber Alerts are disseminated so
> quickly.
> Surely there must be some form of authentication and then
> rapid transmission to various police agencies, the media,
> and the state DOTs.
As the fact sheet quoted in Pat's "TELECOM Digest Editor's Note" indicated, it's called the Emergency Alert System (EAS). A "primary" AM radio station in each community sends out alert messages. Each message begins with that godawful "buzz buzz buzz" noise, followed by a voice message and an encoded three-letter event code indicating the nature of the alert. The "Child Abduction Emergency" code is CAE.
A list of event codes is at
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Equipment at reception points monitors the primary and responds to the codes accordingly. A radio or TV station issues an alert either immediately (automatically, interrupting programming) or within a few minutes (manually, at a logical break point). Automatic equipment at cable tv headends inserts a crawl on some/all channels immediately (satellite TV operators are exempt). Newspapers may do a story. Other agencies take whatever action is appropriate.
Further information: FCC:
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Neal McLain