What about satellite signals? I assume almost every modern vehicle these days comes from the factory with a satellite radio.
Doesn’t satellite radio require line of sight for communication?
I believe so, but I can count on one hand the number of times my XM radio lost it’s signal in the 20ish years I’ve had one in my car.
That’s not a safe assumption; cars may come with that as an option, but even if your car is equipped with a satellite radio, it requires a subscription with SiriusXM to actually use the satellite radio.
As I understand it, yes, it does. In major US cities, SiriusXM has terrestrial “repeater” signals so that users in cars can maintain signal even if their line of sight to the satellites is blocked by tall buildings, parking garages, etc.
I can confirm that, when I travel outside of the downtown Chicago area, yes, my car’s SiriusXM satellite signal cuts out if I go into a parking garage.
But the radio is still getting the signal. They could still push an emergency alert to radios that the car could listen for and switch over to appropriate station when necessary. Same way your phone will get an emergency alert (and be able to call 911) even if it doesn’t have an active subscription.
You’ve obviously never driven between Nashville and Knoxville.
Possibly. Bear in mind that SiriusXM is a national signal; most emergency alerts (e.g., severe weather, fires, etc.) are quite local. If you are in Chicago, do you really want your radio to keep giving you emergency alerts for, say, Houston?
It would require SiriusXM to be able to narrow such broadcasts to radios in the area affected by the alert (I have no idea if their technology allows it). It would also probably require a radio which would be set up for the satellite band to automatically take over the radio, to broadcast the alert (again, I doubt that current satellite-equipped radios have that feature), because if you don’t have a subscription, you’re not going to be leaving your radio set to the satellite band, because the only signal/channel which a non-subscriber can listen to on SiriusXM is a looping ad encouraging you to subscribe.
Where the signal does cut out in parking garages, around some tall buildings, etc.
Art has been dead longer than Rush.
Good. 
Agree. All those things @Joey_P said would be technologically possible.
But unless that capability has been mandated by the Feds for years decades now, Sirius’s satellites can’t do it and neither can the Sirius receivers in today’s cars. Once the Feds require it, there could begin to be a process of software updates pushed to all those satellites and cars. And as you mention, local area repeaters.
But decent bet the update process for the cars (other than maybe Teslas) would require the car be brough to a dealer to reflash the car’s factory radio software. Which doesn’t address Sirius receivers that didn’t come with the cars they’re installed in.
etc. There’s a big job there.
There would be, for certain. And I have a hard time seeing the will, either in the government or at SiriusXM, to make that investment, given that – save for the interference issue with some EVs – AM radios already easily fill that role with no need for new infrastructure or modifications to current cars and radios.
I also suspect that SiriusXM has already had its heyday, and that streaming is rapidly chipping away at its audience for getting an in-car satellite radio. (Note that I say this as someone who has had a SiriusXM subscription for 15 years, and loves it.)
Satellite radio i.e. Sirius carries few AM stations, particularly omitting ones in medium and small markets.
In my experience, no, they generally don’t carry the feeds for local radio stations.
SiriusXM carries some national radio networks (e.g., an NPR feed, an ESPN radio feed, the CBC and BBC radio news feeds); the only time I’ve ever heard actual local radio station feeds is during SiriusXM’s sports coverage – for several U.S. sports, they carry the local broadcasts of games. And even those are probably not the feeds for specific radio stations, but the “[Team] Radio Network” feed, which also goes out to all of the local radio stations in the team’s market which carry the games.
Many local stations can be streamed now, via iHeartRadio, Audacy, etc., or on the stations’ own websites.
Not easily accessible in your car though.
Agreed, unless you have it set up to stream via your smartphone.
Regardless, the point is that satellite radio isn’t set up to do what terrestrial radio currently does well, regarding local emergency broadcasts.
In the US, AM frequencies 530kHz & 1700kHz are reserved for emergencies. That way local highway departments can just have a notice telling drivers to tune in to one of those frequencies for local information. Satellite radio wouldn’t work. A driver in Peoria doesn’t need to know that I-40 west of Asheville has been washed out again.
Because we’re dealing with computers, not dumb analog transistor radios, satellite radio could readily be made to work for this use case. I’m not saying it does this now. But it could readily be programmed to do so. The only hard part, and it’s a doozy, is rolling out those software changes to everyone’s receiver.
Conceptually speaking every EMS message would include the geographical area it’s applicable to. The Sirius receiver can have a GPS receiver, or query the phone or car it’s installed in to get it’s current GPS location. Then determine whether the coordinates of the receiver are within the message’s geo-scope. If so, display / play it. If not, not.
There is already a decades’ old Federal standard for computerized emergency messaging. See Common Alerting Protocol - Wikipedia. Which is used for everything from the highway signs you see warning of Amber alerts, to weather radios and phone weather apps, to the messaging sent via the existing Emergency Alert System - Wikipedia.
Configuring Sirius to be another conduit for this content is comparatively trivial.
FYI all. The latter wiki cite and it’s companion article(s) are a great primer on all the various overlapping message dissemination systems in use in the USA today.
The big question is, what if you are driving in the afternoon? Satellite radio works all the time, but AM radio only in the morning.
//i\\
This would be some level of complication for the (still not in full production) Slate EVs (base model is a small pickup truck, it can be morphed into an SUV as well) as their production model does not carry the means to install any radio of any kind. I think it would be not trivial for them to do so, as well as adding to the cost.