prd09.prod.outlook.com> 9eaab260   
   From: address-withheld@invalid.telecom-digest.org   
      
   Three of the links to the Primary Entry Point (PEP) transmitters   
   (originally ~33 mostly AM stations) were independent from the   
   internet.  There was a dedicated phone line (TDM at the time), a   
   satellite (which I believe is now IPAWS and/or IPAWS over EMNet- it's   
   hard to keep that straight), and a XM satellite radio added later   
   which serves as a parallel distribution chain.  One assumes the phone   
   lines were migrated to MPLS, not internet.   
      
   At the PEPs these national level alerts are injected into the   
   transmitter audio input- there is no requirement for a remote studio   
   or studio transmitter link (STL) to remain.  In fact the original PEPs   
   had a small console at the transmitter so they could originate   
   programming if the studio failed.  Most PEP transmitters doubled as   
   fallout shelters.  The "fill in PEPs" added post Y2K did not have the   
   fallout shelters, but I think they retained the consoles.  They bult   
   out CONUS coverage during daytime, and added Guam, American Samoa,   
   CNMI, and Caribbean coverage.   
      
   Some states have the ability to reach their state primaries over   
   satellite or over fixed microwave, or via dedicated VSAT terminals   
   (granted these might not be the direct transmission of the national   
   audio stream).  NPR also carries the national level alerts over their   
   satellite squawk channel, so that represents yet another source of   
   injection (and over time, so stated migrated their local primaries to   
   NPR stations since they were two steps closer in the audio chain as   
   long as their satellite was up.   
      
   Non PEPs are certainly vulnerable to a STL failure, and the radio   
   stations are almost guaranteed to install their ENDECs in the control   
   room to allow management of required weekly/monthly tests, but the   
   dead air if a station looses it's STL completely is likely to cause   
   users to tune in another station.   
      
   When Alabama implemented EAS, we had an extremely robust instate   
   distribution chain, with the EMA being able to inject message into the   
   two state primaries independent of the PSTN, and over two statewide   
   broadcast satellite networks (I suspect two so they could carry both   
   Alabama and Auburn football at the same time), and most stations   
   monitored their local primary, both satellite networks and NWR.  But   
   no state primary could actually receive a PEP message 24 hours a day,   
   so it had to be received by a public television station in Mobile (far   
   SW corner of the state) and sent up a fairly robust microwave system   
   across the state.  This was latter fixed and Alabama got one of the   
   first "new" PEPs in Birmingham (WJOX-AM).   
      
   You may hear (correctly) that stations get their EAS alerts from the   
   internet- this is the preferred path when it is available to preserve   
   audio quality and get the complete Common Alerting Protocol (CAP)   
   message.  This doesn't mean this is part of the resilient   
   distribution. For the lest decade, all stations, at least without a   
   waver, must have a IPAWS compliant encoder/decoder with a internet   
   connection, but this doesn't remove their requirement for 2   
   connections to 2 other sources.   
      
   As to the radio stations not passing on the message, it's automatic.   
   A EAN or NIC message opens a live audio path from the president (EAN)   
   or FEMA (NIC) to every participating EAS station.  There are problems   
   in the distribution chain, but those PEPs are directly interrupted by   
   FEMA.   
      
   Wow, I was just going to point out that STLs don't matter for the 77   
   PEPs.   
      
   Pat   
      
   --   
   These are my personal opinions.   
      
   **********************************************************************   
   *                          Moderator's Note   
   *   
   * I had to revise the threading info of this post. I chose to place it   
   * in the threading after another post which discussed technical   
   * aspects of the alerting structure. If I got it wrong, that's on me.   
   *   
   *                                                       Bill Horne   
   **********************************************************************   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)