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willow_hiller
Well-Known Member
I don't know anything about radio frequencies, but after some quick searches I believe that it's possible for FM radio hardware to pick up AM signals, and with a software update it's possible that those AM signals could be interpreted. That being said, it seems like antennas between FM and AM radios are quite different, so the car may not be able to receive much AM without a new antenna.
willow_hiller
Well-Known Member
Just found a bit more concrete of an article on using software to compensate for the lack of specific radio hardware: Software-defined radio - Wikipedia
But again, without a specific AM antenna shielded from the EM frequencies from the cars own computer, I don't think it would work very well.
But again, without a specific AM antenna shielded from the EM frequencies from the cars own computer, I don't think it would work very well.
Mokuzai
Member
Mokuzai
Member
My Model S has AM radio too...don't ever listen to it myself but I'd imagine they have to do some shielding/filtering to make it work well. Which sounds like unnecessary added cost when most stations are available through tune-in or like you say on FM.
Too lazy to look it up, but someone took a small AM radio in their Model 3 and tuned it. Worked fine, zero interference.
Just because a standalone AM radio works fine doesn't necessarily mean one built into the car would; also depends on conditions, signal strength, etc etc. If you live in a city, AM is pretty much guaranteed to work because the signal would be way higher than any interference. A true test would be comparing a normal ICE car AM reception to the reception of an AM radio inside the Model 3 when signal starts to fade. Also, you likely need to power the radio directly from the car somehow (maybe the 12V cig would be sufficient?).
I would expect a builtin radio to work BETTER than any standalone would inside the cabin. External antenna, choke filtering, etc. are all possible on a builtin vs. a handheld.
A handheld unit would be subject to all of the interference generated by the electric motors (i.e. none in this case) and would have an antenna inside the metal cabin. I'd think that would be closer to worst-case than anything built into the vehicle.
I'd also expect a MUCH cleaner power supply on the Model 3 vs. a traditional ICE car, since there's no alternator/rectifier. Just clean DC power.
Any noise induced by the electric motor on any of the 12V wiring would be coupled into the power supplies. If you're running a standalone unit, then that is all isolated. Hence, you've got an additional interference path to worry about which isn't present in the ICE system (although, ICE cars do have to worry about electrical noise from the motor, spark plugs, alternator, etc).
Also, power supply units powering a radio aren't going to be running straight off the 12V line on any car, ICE or EV. It's going to run through a bunch of converters which will handle all the filtering already. I don't think an ICE car has any disadvantage electrically for it's 12V system. Sure, it's got the alternator noise, but ICE manufacturers go to extreme lengths to make sure the power supplies running off the 12V system filter out all of that.
Obviously it's possible, but cost and reliability in any environment is a tradeoff.
Why would the motor noise be coupled on the 12V bus? The motors operate on the HV bus, and don't (as I recall) have a LV connection at all. I could be wrong about that, but I don't believe so. Either way, any induction would be on the HV bus.
And you really don't think ICE cars have a disadvantage on their 12V supply? Alternators are notoriously noisy and unstable. The output fluctuates wildly, given that it's driven by a belt. Sure, the voltage regulator is supposed to help smooth that out, but there's always a variance, and that's on a known-good regulator. When they go south, anything can happen.
Can't tell you how many cars I've had through the years with a "whine" on the AM frequencies due to either a loose or bad ground, or noise from the alternator. You won't get any of that with a Model 3, that's for sure.
There's a massive DC-DC converter that couples the HV to 12V. It's likely not a huge contributor, but it exists. Purely by having the entire car's frame be the 12V system ground inherently means any interference off the motors is going to get coupled into that ground.
It's also unfair to compare a faulty alternator/regulator or loose/bad ground on an ICE car to a perfectly functional Model 3. Pretty sure a bad DC-DC or a loose/bad ground on a Model 3 could cause similar issues. This isn't isolated to ICE vehicles.
You're misinterpreting my statement about the 12V system comparisons. I don't think the resultant power on the radio subsystem driven by the 12V supplies will be any different. ICE guys know how to filter out all the noise from the alternators and have done so for years. That's standard fare for them. You don't have that design requirement for EVs so their power conversion from 12V to whatever is going to look simpler.
I'm in Northern NJ. Fortunately Tesla Model 3 has an FM HD tuner,. We get all the larger AM stations as an FM HD2 or HD3 station. For example 101.1 WCBSFM also has CBS AM as 101.1 HD2; 1010 Wins AM is at 102.7 HD3. see Stations - HD Radio The FM HD reception for AM stations takes a half minute to zoom in and lock on but it's very good quality, beats AM reception.
I just wish I could rename the stations on the Favorites list. I used to be able to do this on my Cadillac. For example, I’d like 102.7 HD3 to be labeled “WINS” ....
It sounds like a great thing for a software update. That said, I remember what a big deal it was getting an FM tuner in my first car. My sister only had AM in her Corvair. My VW had an aftermarket Blaupunkt that pulled out. AM and FM; you could pull it out and plug it in as a portable radio using an 110v powercord. Speaker was built into the radio! Used to carry into work with me for overnight shift in the bakery.
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