[EAS] Furthermore re: Fire

[John Willkie]

Let's keep these two things separate.  ATSC 3.0 contains (actually, it's been part of ATSC standards for over 5 years) a transmitter to viewer warning mechanism that will wake up receivers and provide the ability for targeted (including polygon-defined) warnings  It is encapsulated into IP datagrams. All good.

The statewide network is something quite different.  For a while, many PBS stations had an "enhanced 911" system that transmitted on packet_id E911 (hex).  Mostly, that system only worked in the lab.  A PBS station hired me some years back to diagnose (remotely) their reception problems that weren't related to RF.

I discovered that in some cases, their system tiing ock and pcr went backwards and was out of tolerance by about 4,000,000x.  The Chief Engineer went over to this "fully funded mandate" device, hit the "bypass" switch and the problem went away. The report went up the PBS silo.  When other PBS stations (including, I believe one or more on this list) did the same, reception problems disappeared.  The manufacturer updated their firmware in 220 PBS stations, but the damage was done, and nobody was paying for this rather dumb, proprietary (for the most part) idea

Maybe that system is what is happening in Ohio or KY.  I can check on the latter.

But, such a system can be relayed from transmitter to transmitter, and the transmitters don't need to be owned by the same entity.  They just have to agree that the system is a good idea, and somebody has to pay for the decoders, encoders and perhaps a new multiplexer.  Its just easier for state governments because everybody (EM, TV, etc) works for the same employer, an employer that can receive federal funding, even for systems.

Basically, the older system traveled on a dedicated pid.  There was no way for consumer receivers to know of the existence of the pid nor its use, because it wasn't referenced in the PAT nor did it have a PMT.  The argument was that it didn't need to be, because it wasn't an MPEG-2 program service.  Even were a receiver able to discover the pid was active, it wouldn't be able to make use of the bitstream.

The easiest way to convey data from transmitter-to-transmitter is SCTE-18.  NO TV set or set top box SHOULD be able to make use of that, but I haven't tested this in the real world.

Best;

John Willkie