7 ms·
This is an important law to pass. Not because of it's intended effects but because of the unintended. I strongly support it. Electrical vehicles' switching pow
by superkuh 3y ago
This is an important law to pass. Not because of it's intended effects but because of the unintended. I strongly support it.
Electrical vehicles' switching power supplies are terrible radiators of low frequency radio. As the articles say, this radio interference is why auto-makers were removing AM radio. If this regulation passes to law it will have the unintended effect of making auto makers not pollute the entire world's shared radio spectrum and prevent it's use by all. The FCC should have stepped in to bar production of many of these vehicles but I guess congress has it accidentally covered. We can only hope that other nations pass similar legislation.
It is entirely possible to minimize and mitigate these conducted and radiated emissions. It will just mean hiring RF/Power EEs to know where to put the caps, how to run a controlled impedance line, etc.
- mlyle 3y ago> It is entirely possible to minimize and mitigate these conducted and radiated emissions. Reducing EMI down at medium wave from motor drives is really, really hard. Filter networks that keep most of the switching frequency out of the motor and motor wiring are big, cost money, and reduce efficiency.
- dylan604 3y agoso instead of making the silent electric cars make some sort of noise for pedestrians to hear, they should all just carry a device susceptible to the EMI an EV generates to allow for proximity awareness of a silent EV approaching. /s I know nothing about the technicalities of why this specific EMI is hard to eliminate, so I'm asking an honest question. Why? What makes it difficult to block this EMI? Where is it being generated (I'm assuming the motor windings??)? Is there not some sort of cage that can be built around the motors by lining the wheel wells to block the EMI?
- theatrus2 3y agoSimple: motor inverters are switching power in this frequency range. It’s already below FCC limits for unintended radiation - it’s not going to block AM activity far from the vehicle, but putting the antenna in the midst of all that radiated noise is challenging.
- mlyle 3y ago> It’s already below FCC limits for unintended radiation When things are brand new and in good condition, yes, probably.
- mlyle 3y ago> Where is it being generated The motor controller is turning the motor on and off rapidly in this frequency range to control the power in each winding. The inductance of the motor converts this to a near-constant amount of power. > cage that can be built around the motors The motors already have shielding and the wiring does, too. But when every car has peak RF output of hundreds of kilowatts, not too much of a fraction has to leak out to completely jam the AM band.
- wvenable 3y agoThe law says they need AM radio -- it doesn't say it needs to be good.
- KerrAvon 3y agoIf RFI interference is the actual problem, this is a terrible bill because it does nothing to limit that. Regulate for the actual problem; unintended consequences will always have other unintended consequences.
- remorses 3y agoIf only there was a way to make radio signal clear even with background noise. Maybe one day someone will invent frequency modulation instead of this stupid AM thing
- erellsworth 3y agoI wouldn't get your hopes up. Depending on how the final bill is written, simply equipping the vehicle with an AM radio might be enough to satisfy the regulation, even if the reception is so poor as to make it almost unusable.
- toomuchtodo 3y agoSoftware defined malicious compliance. “Sure, it can tune to AM. Ticket closed.” Just keep kicking the can until the last ~4k AM stations in the US close.
- giantg2 3y agoAren't there also information and emergency stations run by the state DOTs? I've seen signs to tune to AM stations on roadways.
- dghlsakjg 3y agoThey also do it on FM in some places, I don’t think it matters a great deal what band it is in.
- thsksbd 3y agoIt matters a great deal. While AM quality sucks, the modulation is more robust than FM and the AM band (specifically as opposed to the modulation) can go much further.
- ethagnawl 3y ago> ... can go much further. I've been exploring the AM dial since this issue first arose a year or two ago. So far, the furthest transmission I've knowingly received was a station in Chicago while I was in NW Connecticut. I've also heard of people in the NE US receiving transmissions from Central America and Europe, especially at night (the sun causes some amount of interference).
- itishappy 3y agoWhile I agree, this bill doesn't appear to put any pressure on automakers to reduce RFI.
- deleted 3y ago[deleted]
- wcfields 3y agoHey HAMs: You thought the noise floor was bad now, wait a few years when huge RFI vehicles are roaming all over the place.
- walterbell 3y agoThe better to see you with, my dear, said the sky to the fly.
- lightlyused 3y agoActually, they really are better than ICE vehicles. Alternators are horrible.
- giantg2 3y agoReally? I always thought it was the coils firing for the spark.
- hunter2_ 3y agoI thought it was the spark itself.
- thsksbd 3y agoI was under the impression that the FCC has mandated spark ignition standards for the better part of a century. Shielded spark plug cables with a return path for one.
- zmgsabst 3y agoOnly ones with spark plugs. Diesel engines don’t produce such electronic noise — hence why they’re used in radio quiet zones.