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Comment by jcgrillo | Hacker News Reader

The manufacturers' chief objection seems to be that EV motors interfere with AM signals, therefore the AM band needs to go away. Not an EE, but for what little I understand of FCC mandated EM compliance testing, this seems like an absolutely ridiculous argument and I hope the automakers are swiftly and harshly taken to task for it.

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As far as I can tell, electric cars are regular old FCC 15b devices, but the emission limits are generous enough that an AM radio can't operate from inside of one, the same way you wouldn't expect an AM radio sitting on top of a generator to do well.

Thanks this is interesting context

That is interesting from a mass-implementation standpoint. I wonder how many Tesla vehicles working right next to each other would squash AM reception for a given radius around the group of cars with current EM emissions.

In theory, they could form some sort of phased array beamforming to fuck one guy in particular, but ignoring that sort of targeted malice, and assuming non-correlated noise and a non-directional receiving antenna, the inverse square law would dominate and the overwhelming majority of the interference would just be the closest Tesla, not the total volume of Teslas.

Any chance they could unintentionally synchronize by interfering with each other? Many systems naturally do this but I'm unfamiliar with inverters on this level so I have no idea if it's feasible or not. Maybe car manufacturers have thought of this and intentionally use slightly different frequencies across vehicles or just shield their clock source from interference?

It would not surprise me in the slightest if someone has considered using coherent wave forming from electric vehicles as a targeting mechanism. In a malicious-actor scenario, EVs often have GPS which can provide a pretty accurate time-synchronization mechanism. With enough collected GPS points to eliminate significant error and fine-control over the inverter phase/frequency it seems that it would definitely be a possibility given the number of EVs in many urban areas. Heck, most EVs are even internet connected for software updates.

I have (my kid has actually) a 2022 Nissan Leaf with AM receiver. Perhaps newer EV designs are different in some way, such as the placement of the electric motors. Stellantis has stated they moved the radio receiver components away from the EV related systems to maintain good reception.

AM antennae are simple affairs -- usually just a stick of carbon with a tiny spool of wire around it. Seems like you could just relocate it to an end of the vehicle and put a bit of shielding around it. If that doesn't do it, then the car is a massive emissions vehicle. (pun intended)

Also it seems like the interference shouldn't occur if the vehicle is not moving or is turned off, and that's still useful for emergency situations.

But then you are merely equipping the car with emergency equipment, so why not a knife and water filters?

I know you're being sarcastic, but it seems like EVs should probably also come standard with a glass breakage device for fast escape.

I generally don't find reductio ad absurdum arguments very convincing.

For example: seat belts and air bags add extra cost (a lot more than an AM radio), maybe they should be optional too?

The FCC interference requirements are designed to prevent your usage from interfering with others. It's perfectly acceptable to interfere with radio signals for yourself. Anyone who grew up in the 90's and had a car without a built in CD player has used an FM-transmitter to broadcast the audio of a portable CD player to their radio, interfering with any other FM signals on that frequency, albeit in a very small area around the car.

Clarification: everyone in the US. These small transmitters were not legal in many other parts of the world

Still useful today. I still use an Avantree (https://avantree.com/collections/bluetooth-transmitters-rece...) on my visor everyday to broadcast from my bluetooth phone to my early 2000's vehicles with "vintage" AM/FM/CD stereos that I think are really cool and I'm quite unwilling to downgrade just to get bluetooth.

I haven't been in the business for a while, but I remember learning that the EM compliance rules have some special carve-outs for electric motor control systems.

Kind of ridiculous for something that could be solved by a paper thin wrap of copper mesh around the motor.

Years ago I met someone who was a high up / owner of a EM testing facility.

He took me of a tour of his facility, and we went into chambers that were radio and acoustic silent. I then asked, "uhm, normally electronics aren't this big, what are you testing in these?"

"Oh, we test cars for EM in here"

"Uhm, those doors seem a little small for a car. Are you testing the Tesla?" (At the time, the very first Tesla Roadster wasn't on the market, but it was probably the only car I could think of that would fit through the doors.)

He then lowered his voice and got very cagey. "We don't talk about our customers" was his response.

A few minutes later the tour ended in his office. He asked me to walk around his desk. There were pictures of him all over the Tesla Roadster, clearly excited to have it grace his presence.

The funniest thing: He wasn't allowed to drive the Roader.

(Conversation is paraphrased)

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Ironically, I wonder how easy/hard it will be to have a functional AM radio in an electric car. Is it one of those things where all you need to do is twist the right arm, or is it something that's practically impossible?

Put the antenna on the roof and the receiver at the buttom of the antenna.

ICEs have electric motors too.

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