TFA mentions AM causing interference in EVs. More accurately, it's hard to isolate an AM antenna from a transformer system. AM reception in EVs is a feat of engineering. FM and others still require care but are comparatively easier.
AM is unique in its propagation. It can travel very far very easily and even bounce off the ionosphere in "shortwave" AM situations. It's hard to imagine any form of broadcast radio beating AM at its own game here.
Satellite radio could work, but satellites are a lot more expensive than a radio tower.
We've been batting that since forever. Having a 3 phase inverter switching 500 Volts at a few kHz does tend to radiate a bit. But it can be controlled and has been so far.
No. “AM causing interference in EVs” would be that you turn on an AM transmitter and the EV motor starts to shutter or loses power. But that is not what we are talking about. It is that you turn the EVs motor on and the AM reception becomes noisy, isn’t it?
It is not about who has been around sooner, or who is more important, but what degrades in the presence of what.
Wrong. If you really want to get pedantic, EM forces affect everything the same way (in line with Newton's third law). So you can have an argument for both sides. But preferring one will always be wrong. Especially if you disregard outcomes that can be felt by humans as you did.
The interference is still coming from the car regardless of which function you think is more important. AM radio waves aren't messing with the car, it's the other way around.
Maybe someone can explain why the modulation scheme matters, instead of the frequency range. AM less sensitive to phase noise? Or is it that AM radio typically means some frequency range?
With AM, any noise is just, well, straight noise as AM is a straight amplitude signal.
FM is a phase modulation scheme, so random noise is largely discarded, as instead you have a phase tracker tracking frequency modulation.
Basically AM will always have noise, but because of how simple it is unless the frequency is being totally trampled on you can get * something* from it.
FM by contrast will have almost perfect tracking with very low audible noise in the output… right up until the PLL loses tracking and you lose it all.
Perhaps Switching in the inverters of the EV will generate harmonics that are in the 540-1700khz AM range. Pulses of current in a wire between inverter and motor radiate fields which are then picked up by AM radio antenna. Because AM is amplitude modulation it is more susceptible to interference by a signal on the same frequency, whereas an FM station uses a band of frequencies to encode the information instead of the magnitude of a carrier.
Guessing
AM and FM radio at least in the US refer to both the modulation and the frequency bands.
AM is 530 kHz – 1700 kHz, using 10 kHz spacing
FM is 87.9 MHz to 107.9 Mhz with 200kHz spacing.
IMHO, there are enough AM driver information stations that I would be upset when I eventually learned I couldn't receive them on a car with no AM radio. But it might take several years for that (especially if it's an EV; I'm not taking that into the mountains, probably)
Because being in a remote and sparsely served area is exactly the kind of place where it's vastly easier to ride your thumb to the nearest gas station and get a couple gallons of gas in an emergency than to arrange charging or a tow?
Why would you be out of gas in the mountains in the first place? Because you got snowbound and ran the car every couple hours to get some heat out of it.
Also ease of repairs in rural areas. Bubba’s Auto down the road probably has enough duct tape, clamps and experience to get most ICE cars semi-functional if they’re not totaled. A friendly home owner may even loan you tools to work on an ICE car.
Nobody in Bumfuck, Nowhere is going to have the tools or technicians to try to repair an EV. It will likely be a long and expensive tow to somewhere that does.
> Because you got snowbound and ran the car every couple hours to get some heat out of it.
Complete tangent, but how do EVs handle low-traction surfaces? Seems like they might do better on average from the weight, but that’s a wild guess on my part.
It depends on the programming and what tires you have. Electric motors have an enormous amount of instant torque which is exactly what you don’t want in a low traction situation.
The real danger on highways is traction control. It can hide how slippery the road is and allows you to easily outrun your braking ability.
In the northern Midwest, you’ll see car after car in the ditch when it hasn’t snowed in a while.
Early Priuses (Prii? Whatever) were notoriously crap on dirt roads because the traction control was too aggressive about cutting torque when the wheels started slipping, like even imperceptibly. On loose surfaces, you've got to allow some slip or you're unlikely to get anywhere, especially if it's uphill.
As for people forgetting how to drive in the snow over the summer? That seems to be universal. Seen it in Ohio, Massachusetts, Vermont, and New Hampshire.
modulation does not matter for range. however FM requires a greater signal strength to convey the information. if you are trying for distance, AM works with less recovered signal.
exclusive of digital modes, the most distance effective signal is CW. unmodulated signal, on or off.
FM uses 10 times the bandwidth and conveys more audio frequency range within it's signal than an AM one. FM has the benefit that building antenna gain is relatively easy so the Total Power Output of FM transmitters is often lower than for AM transmitters. You can generally expect to get 100kW Effective Radiated Power with only 20kW of input.
AM uses a significantly lower frequency and ground wave propagation is much more likely which gives AM the benefit of being able to reach "over the horizon" where FM simply cannot.
Would it suffice to require either AM or satellite radio? We never buy satellite radio subscriptions, but our decade old car has an antenna, and I assume many newer cars do as well. As long as people know how to use them to tune into emergency channels (I don’t!), it might suffice for EVs.
Why? It not ought to be if you know what you are doing!
It seems a great shame that universities don't teach electromagnetic shielding and screening in digital electronics, or if they do they only gloss over it. Once it was a core subject and everyone understood its importance. Moreover, the failure to teach EMR shielding techniques in 101 electrical engineering has been an ongoing saga for decades, it's why digital people end up with little or no concept of the issues that confront engineering in the small-signal analog world.
This lack of training and the failure to emphasize the importance of proper spectrum management, which, in short, is the science of using RF frequencies efficiently without causing interference, is the principal reason why digital people don't seem to give a damn about the RF/EMR pollution and noise emitted from their switching circuits. Now opportunistic EV manufactures have the damned hide to try to sweep away the last vestiges of prudent spectrum management.
Fact: if you cannot listen to a normal broadcast AM radio transmission within its authorized service area on a car radio then the EV's electronics is polluting and radiating noise beyond normal acceptable limits. QED.
One sees crappy almost non-existent shielding everywhere from domestic electronics through to huge Tesla coils that completely block out swathes of radio spectrum for many tens of kilometres. Under ITU and national spectrum management laws such behavior is supposed to unlawful but no one including the FCC does anything of consequence about it (once if you emitted radio noise you'd soon find radio inspectors clambering all over your equipment with RF noise detectors).
Over the past 40 or so years the electromagnetic spectrum, especially HF frequencies, has, in parts, become almost unworkable because of crappy noise from digital electronics and the principal polluters are those in the digital electronics world. Let's be clear what we are talking about here: they are polluters and it's pollution like any other green issue—think of oil spills, chemical residues, nuclear waste, now add to that list electromagnetic pollution.
About 20 years back NATO did a report that indicated the background noise floor on the HF spectrum had been raised by about 6 to 8dB because of unwanted electrical noise. Several years back at a SMPTE engineering exhibition I quoted this figure to the chief engineer of a manufacturer of HF transmitters and he looked at me with surprise and asked where had I been in recent years, he then informed me that the then current noise figure had risen to about 17dB!
That level of EMR pollution is outrageous, it's clear that parts of the RF electromagnetic spectrum are already unusable.
Imagine how bad the EMR pollination will be if these bastard EV manufactures get their way and when there are millions of EVs on the road without adequate EMR suppression. Not only will all long wave, AM and HF bands be unusable but so too will large sections of the VHF band.
For those who don't understand the problem let me put it into perspective. These EMR shielding problems were solved in the 1930s when aircraft used HF radio (≈3-30MHz). Aircraft HF radio receivers have to be about an order of magnitude more sensitive than normal domestic AM radios because the incoming signals are so much weaker. That didn't deter RF engineers of the day, now all aircraft electronics are properly shielded.
So what's wrong with the EV engineers? It seems to me it's a combination of cost-cutting and ignorance.
This law must succeed!
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A few basic references for the untrained:
MIT Radiation Laboratory Series vol 23 - Microwave Receivers, Ed: S.N. Van Voorhis, 1948.
Noise Reduction Techniques in Electronic Systems, Ott, Henry. W, 1976, Wiley.
> For those who don't understand the problem let me put it into perspective. These EMR shielding problems were solved in the 1930s when aircraft used HF radio (≈3-30MHz). Aircraft HF radio receivers have to be about an order of magnitude more sensitive than normal domestic AM radios because the incoming signals were so much weaker. That didn't deter RF engineers of the day, now all aircraft electronics are properly shielded.
Thanks for the history, precedents and references.
> Under ITU and national spectrum management laws such behavior is supposed to unlawful but no one including the FCC does anything of consequence about it (once if you emitted radio noise you'd soon find radio inspectors clambering all over your equipment with RF noise detectors).
Well, back then radio inspectors didn't have to fear getting shot.
Snark aside: it's only getting worse every day. Temu, Wish, Alibaba, Amazon dropshippers - almost none of the stuff they sell has passed any kind of compliance audits, and they aren't even required if the device in question isn't intended to participate in RF communication. That is the real culprit... all these billions upon billions of small devices with high frequency voltage regulators that all act as (very) tiny RF emitters.
And even if you'd begin to teach about shielding and EM suppression in electronics design courses, it would be pretty useless against the infamous magics of "gongkai". Just look at this $12 phone [1] - no RF shielding anywhere despite the thing literally being a cellphone. And yet if I were to order one of these, even an entire batch, chances are high no one would ever stop me.
Somewhere along the way EMI requirements stopped being enforced. From my observations this mostly happened in the 1980s when deregulation of the telecommunications industry happened around the world. Governments started outsourcing their Spectrum Management departments to private enterprise. These industry bodies were much less concerned with matters such as interference.
"...it would be pretty useless against the infamous magics of "gongkai"
True, but as I just posted to buescher we, as a society, will have to rethink the EMI problem and this will change the whole approach to electrical engineering per se. Protecting the electromagnetic spectrum will need to be considered of paramount importance (as our communications infrastructure depends on protecting it).
Like chemical engineers, considering the effects of EMI pollution levels will have to become the first step in any electrical/electronic project.
This also means tighter regulation and possibly new laws.
> Protecting the electromagnetic spectrum will need to be considered of paramount importance (as our communications infrastructure depends on protecting it).
I wouldn't be that sure.
Yes, there is a lot of garbage and congestion on the spectrum, but thanks to new approaches to (forward) error correction, higher quality RF parts and especially the explosion of compute power, we can achieve ridiculous communication quality. And it's not new either - GPS is orders of magnitude below the noise floor, and yet, we got "smart collars" for cats and even birds capable of decoding that signal.
Pretty much the only ones who actually have a problem with all the garbage are hams, and to a lesser extent air traffic control (for them, it's mostly people with garbage handheld radios, and dumb pilots not switching from ATC to onboard communications).
Well, yes, but electric motors and drive circuitry are particularly nasty emi sources. One poor-man's susceptibility test is to run a handheld drill motor as close to your circuit board as possible. In an EV, you're driving around inside one.
"Well, yes, but electric motors and drive circuitry are particularly nasty emi sources."
Agreed, but that noise can be contained with an effective Faraday screening.
If noise escapes then the shielding isn't working properly.
It seems to me that electrical engineers—especially those working in high speed digital electronics—need to think like chemical engineers who spend much of their time in the containment business. Safely containing dangerous polluting liquids and gasses is a basic premise in chemistry. Most of the engineering infrastructure of large chemical plants is involved with containing chemicals and doing so in ways that are safe and do not pollute the environment.
On the other hand, electrical engineers have a dangerous waste product—EMI—that they'd rather forget about. Well, I suggest that in today's world that thinking is just not good enough.
Put another way, when building electrical/electronic systems start with the foundation which is to ask what pollution or damage will this project cause. The first question is to ask yourselves what are the shielding/EMR requirements for this project. Chemical and civil engineers start with such requirements as a matter of form and good practice. So should electrical engineers (you do this now re electrical safety, so you just have to extend that thinking to RFI).
It's now time electrical engineers started to work in the same way. RF shielding and protecting the electromagnetic spectrum should no longer be considered an inconvenience and afterthought but as a major component of the project.
BTW, by adopting good shielding practices you'll be preparing yourselves for the next Carrington Event. Remember RF shielding works both ways—in and out!
> Agreed, but that noise can be contained with an effective Faraday screening.
I don’t think car manufacturers are saying they don’t know how to shield, they’re saying it would come at a cost:
"Requiring the installation of analog AM radios in automobiles is an unnecessary action that would impact EV range, efficiency and affordability at a critical moment of accelerating adoption," -the fine article
Well, what are those costs? Perhaps they're not wanting to resign components that were badly design in the first instance. If so, then that's unacceptable. Moreover, a redesign would benefit over the long term.
I smell short-term thinking here and concern over their current problem of falling profits from EVs
AM is unique in its propagation. It can travel very far very easily and even bounce off the ionosphere in "shortwave" AM situations. It's hard to imagine any form of broadcast radio beating AM at its own game here.
Satellite radio could work, but satellites are a lot more expensive than a radio tower.