[EAS] Buffering or Joining in progress feeds: concept of operations

[Sean Donelan]

On Thu, 10 Nov 2011, Kluger, Michael wrote:
> Unfortunately, not all EAS units provide the EAN buffering feature that 
> Harold described.  When our EAS unit auto-forwarded the test, after 
> transmitting the SOM and attention signal, it joined the unbuffered 
> incoming audio in progress, upcutting the portion that had gone by while 
> the SOM and attention signal were being sent.  As a result, our audio 
> started with "...a nationwide live code test", but we lost "This is a 
> test of the Emergency Alert System.  This is only a test.  "The message 
> you are hearing is part of".

WIthout knowning what is in the White House concept of operations for 
"real" EAS/EAN messages, it isn't possible to really answer the question. 
Either way can work, and both ways have potential problems.  But for 
interoperability, the issue is different people can make different 
assumptions.

Tbe old published EBS concept of operations for presidential messages 
included a 2 minute stand-by/talk-up script.  The published FCC rules for 
the current EAS/EAN say that the message must be carried "live."  But the
FCC didn't publish a revise concept of operations for the presidential 
message, so its not clear whether a presidential message will still 
includes a lead-in script.  I suspect in the early 1990's when the EAS 
rules were being written, equipment for digital buffering was still 
relatively expensive, so industry and the FCC left it undefined because 
equipment was directly switching the audio.

In addition, whether buffering is considered "live" or recorded is one of 
those things communication engineers and communication lawyers don't 
always speak the same language.  Is a DVR program recorded or 
time-shifting?

When I was working on procedures for EAS for IPTV/ATIS standards, that
was one of the questions I tried to get clarifications from FCC; but never 
got any definitive answers.  Different EAS encoder/decoders on the 
market did different things. Sometimes the same encoder/decorder did 
different things depending on how it were configured, i.e. configured to 
manual/automatic forwarding EANs.  Whatever choice you make, an upstream 
station in the daisy chain may have different equipment, configurations, 
or assumptions.

But now CAP is coming, so hopefully they have everything figured out.