That's the way EAS already works. Local stations EAS decoders are set up to automatically forward alerts from local authorities, FEMA, NWS, or iPAWS. That includes live alerts.
Are we thinking about different kinds of live alerting? My understanding of the existing EAS topography is this. Say an origination point like county OES sends out an alert that's read and transmitted live. Say it gets transmitted on some county-wide VHF frequency like 158.565 MHz, by a hardline to the nearest NOAA 162 MHz transmitter, and by two microwave point-to-point links to the local LP1 and LP2 stations. When that happens, the LP1, LP2, and 162 MHz broadcast signals will contain/relay that live OES alert message as it is originating live from the OES. But if no other broadcasters in the county have direct VHF/microwave/wireline links from the county OES, then their EAS receivers will
record that alert, while it is live, from either the LP1 or LP2 or 162 MHz signals, and wait until it finishes being broadcast before turning around and initiating their own non-live replays. That's my understanding of EAS -- that if an originator chooses to speak live, their voice will be live to the public, but it will only be heard live by any listeners listening via the main arterial distribution link-connected broadcasters ... that all other listeners down the chain will get replays in a store-and-forward cascade.
That said, what I meant by live in my original post was this. Imagine the same scenario as above (live transmission from OES, relayed live by the NOAA/LP1/LP2 stations). But when the OES originator sends his EOM tones, the NOAA, LP1, and LP2 EAS receivers see an extra command embedded in them saying "when these EOM tones finish playing a.k.a. when you finish relaying these EOM tones live to air, don't cut back to your local station audio; instead, stay in interrupt mode, and start relaying audio from the 'live augmented emergency audio' baseband audio input on your back panel." And connected to that input on those stations' EAS receivers is the baseband audio output from some wideband FM 450 MHz broadcast auxiliary band receiver that just listens 24/7 to, say, 450.2 MHz, which is a high level mountaintop transmitter over which the OES sends out its live, continuous audio broadcasts of the nature I described in my original post. Any other broadcasters storing-and-forwarding the NOAA/LP1/LP2 stations' live-relayed alerts would
stop recording upon the EOM tones, to make sure they didn't keep recording the 450 MHz passthrough audio when it began on the 162/LP1/LP2 stations following the EOM tones. Those other broadcasters' EAS boxes would, during
their replays, notice the same "switch to your 450 MHz receiver after these EOM tones" command embedded in those EOM tones, and they'd do so. And so it would go, down the cascade.
If this is what you meant EAS can already do re: live audio, then I'm sorry I just made you read all this. When I first got into the weeds of how EAS worked two decades ago, it didn't have the ability to work this way. I just pictured this method in my mind because I felt it would be the best+simplest way to augment EAS for long-form live takeover of automated stations. If there weren't a separate, dedicated 450 MHz type frequency to convey the "live all day long" post-initial-alert OES audio, then that audio would have needed to have been distributed in a cascading style (OES > LP1 > some FM station > some cable company). In that case, LP1 and "some FM station" would get trapped into acting as perpetual ham repeaters and not able to resume their regular programming or else "some cable company" would lose its live audio source. The way I pictured it, with a separate venue for the "live all day long" audio (like 450), any stations that had 24/7 staffs and didn't want themselves taken over in this way could just flip a switch on their EAS boxes to tell them "ignore when the EOM orders you to stay in interrupt mode and switch to your 450 input -- just give back control to the DJ right away, like you always did."
The problem is that local municipalities typically don't train, let alone drill on activating EAS.
While a few agencies have outstanding communications skills (usually because they've hired former broadcasters), the vast majority just don't. Briefings aren't frequent enough, they're full of institution-speak instead of clear writing, and very few have any sense of how to deliver quality video and audio to broadcasters. They're in no position to deliver the kind of clear and constant messaging that would be needed if you're going to expect them to take over the airwaves of local broadcasters for an extended chunk of time.
I've noticed this ever since EAS was first deployed, yeah. It's a real problem even with the short alerts that exist now. Besides coherent public addressing skills, some of the emergency alerts I've heard had only slightly better intelligibility and fidelity than the drive-up order kiosk in that old "Fast Food" track by Stevens & Grdnic.
In my original post, I suggested that the origination point for this theoretical "live all day long" service would be a single county OES point -- and that having a few employees to man that cubicle (one per shift) would be enough to allow patching in other feeds, on top of the one on duty narrating and speaking to the public him/herself. I guess when I imagined that, I also imagined that
somebody would give them proper mics, a proper acoustic booth, and training.
When the you know what hits the fan, local emergency services usually are spending time trying to save lives on the ground, not worrying about who might be listening to radio.
I get it, Kelly, but in the immediate timeframe, there are still enough people living without smartphones (primarily elderly) to make it worth one person per shift's time to have training in manning a basic booth at one emergency office per county in the event of turbo-emergencies. When the cable system and the copper landline go out to someone's grandmother's rural home and she's sitting in her wingchair with a battery radio trying to find information, and can only get George Noory and automated classic country stations, that's a problem. I just think we need at least one more generation to pass before there's enough modern technology uptake to definitively say emergency alerts over linear radio/TV matter as much as putting them on WWV. And moreover, if the turbo-emergency in question is something that takes out the cellular network, those radios will be what everybody, not just the Luddite elderly, will be searching for information on. So maybe they'll always matter to keep and augment as best as possible on linear.