AM Radio and cars? - Page 1
Forum section: electronics / rf-microwave

author: coppercone2
author_rank: Super Contributor
timestamp: May 15, 2023, 04:50:50 am
content: https://tech.slashdot.org/story/23/05/15/0330255/saving-am-radio---the-case-for-and-againstDo you think its that expensive to shield and reduce EMI or is this a money grab? Based on all the subscription stuff they seem to want for uh... base firmware features relating to blocked integers... I have a feeling its corporate bullshit.I bet 'reduced EMC requirements' for automobiles are gonna result in alot of stuff going screwy too. It feels kind of like "well lets make everyone else's EMC people deal with the problem we make, and lets charge a little subscription fee too by getting nice partnerships with cell phone companies". So lucrative but so evil.Cell phone companies would turn every car in America into a 'customer' and get endorsement deals with the auto makers. Damn that is some easy money.

author: Kleinstein
author_rank: Super Contributor
timestamp: May 15, 2023, 08:05:58 am
content: For a electric powered car it can be quite tricky to avoid interference, especially if there is no good antenna outside the car body. So the effort can be quite significant.They would still need to have some degree of fitlering to no interfere with radios in other cars though.The classic AM bands are anyway plagued with interference from the increasing number for SMPS, even if they individually stay within limits.The main use for AM radio is for more rural / mountainous areas where the FM reception is poor. The poor audio quality makes it inferior when there is FM available.In much of Europe AM radio is dead anyway with hardly any stations left. The new digital radio standard (DAB) with a few more low power repeater stations could replace the coverrage.

author: szoftveres
author_rank: Regular Contributor
timestamp: May 15, 2023, 01:53:26 pm
content: Here in the U.S. am radio is still quite popular - smps interference (e.g. from phone chargers) doesn't go beyond a couple feet of the wires and local AM radio stations are quite listenable on highways and on the city streets.

author: edy
author_rank: Super Contributor
timestamp: May 15, 2023, 06:14:32 pm
content: Just saw some more news about many car makers (especially on their new EV’s) dropping AM radio. Is the interference that bad and can they not reduce it? Don’t they have to keep within some radio emissions standards so as not to interfere with other people’s reception? Certainly it can’t be due to cost… how much can an AM radio cost? Or is there some other reason this is happening (like a user experience or quality perception issue they want to sweep under the rug)?

author: coppercone2
author_rank: Super Contributor
timestamp: May 15, 2023, 08:57:14 pm
content: Well the cell phone companies know they will get a ton of basically life time subscriptions for cars.Ever get the feeling you are not using the infrastructure you built to capacity? Now you will be.And if you have cars behind you , suddenly spectrum related issues are basically gonna be easily allocated, because we need them for cars. The companies were having trouble getting spectrum rights I think. Now the opposing bodies have to deal with the fact that its for common peoples cars, good luck fighting that off.I bet you a car maker, that contract everything out, is gonna contract out huge deals to major cell service providers to deal with cars. And you know they will fight over those contracts. Fords not going to be doing anything 'new', someone else will be begging Ford to do it, since its a steady cash flow.I doubt its a strong technical problem, I think its just someone figured out that it could be extremely lucrative, because subscriptions. Their obsessed with subscriptions now. For all you know it could have been suggested to a board by a liaison, a basis from some technical report that some shitty prototype was interfering with radio and some specific case could be expensive to fix. The cell phone companies have been basically obsessing about how to get more people to subscribe, since they existed, Its a subscription based industry. When someone saw the opportunity they figured this could be pay day.

author: Stray Electron
author_rank: Super Contributor
timestamp: May 15, 2023, 09:05:37 pm
content: I haven'theardof any talk of getting rid of AM radio here in the US. It's not very popular, mostly due to the poor quality of the mostly trash-talk radio programs and Spanish language only broadcasts on there but I think most car owners still want to have that capability. AM is still widely used for emergency alerts and to broadcast local automobile traffic information and I don't expect that to go away anytime soon. OTOH the auto manufacturers are really pushing Sirius and XM and other forms of subscription radio services so it wouldn't surprise me if they attempted to drop AM reception from the car radio receivers. But if they do, I expect that a lot of the car buyers will buy a different brand car that does still have AM reception.

author: coppercone2
author_rank: Super Contributor
timestamp: May 15, 2023, 09:07:53 pm
content: And there is the... after market radio with improved receiver, filters, antenna and shielding that could be installed.Wanna bet that a huge portion of the problem is not wireless interference but "holy shit, we need to put $1.60 of parts into that radio that sub contractor found for us to shield its power stage from the engine, THIS IS JUST NOT FEASIBLE". Or like, "bending the metal this way would require a base factory redesign (i.e. mod some press)" or perhaps "MORE METAL??!!?! WE WANTED NYLON" or even "SHIELDED CABLE IS MORE EXPENSIVE!"I am imagining like a plastic radio box that slides into the console with a 400A bus bar 1 inch behind it or something.... I noticed car makers are starting like like 'mashing' objects, for instance squeeze the filter before you put it into the hole. I kinda wonder if deeper down some where there is like the main power feed just smushed into a body panel groove with a pump holding it in place via some synthetic wadding and hot glue.

author: jonovid
author_rank: Super Contributor
timestamp: May 16, 2023, 04:57:20 am
content: shortly digital processes can help. for example to have dynamic radio telescope noise reduction technology in a single chip? or FPGA?near real time digital noise reduction would make a difference to any analog AM radio reception nowadays.its not like we only have the fixed analog noise reduction filters of the past.

author: Kleinstein
author_rank: Super Contributor
timestamp: May 16, 2023, 09:51:42 am
content: With the rather low AM frequencies there is not much that can be done with the directionality. So there are only 2 maybe 3 if one includes vertical antenna polarizations to work with. So the use of dynamic directinality (like gen 6 cell phones) is limited.Part of the problem with the interference is that it may saturate already input stages. Modern radios got quite good later down the signal path (e.g. with stable LO clocks and good IF fitler), but they tend to cheap out on the input filtering and may thus not be as good in handling really strong signals that are slightly out of band. Strong local interference is more like a thing that modern SDR and similar don't handle that well.After market fitlering could be tricky/limited (e.g. clip on ferrites) with an electric drive car.Some modern cars have the radio as part of the car electronic system. So one would still need the original radio and would need a 2nd one in addition.

author: pdenisowski
author_rank: Super Contributor
timestamp: May 16, 2023, 10:24:46 am
content: The issue with AM radio is that it is very effective at receiving noise: I've actually hunted down power line noise by simply tuning the AM radio in my car to an "empty" frequency and then driving around until I heard the characteristic 60 / 120 Hz "grown" created by power line noise (sample recording attached).My assumption (because I have no personal / professional experience with this situation) is that AM radio is being eliminated because some EV system or systems are generating noise that would be easily perceived when listening to AM radio, and that it would be difficult / expensive to reduce this noise to non-perceivable levels.As an amateur radio operator, I also do have to wonder about the effect these same noise sources would have at HF (or even at low VHF for weak signal operators), since SSB is another form of amplitude modulation. I have yet to see a Tesla with an amateur radio antenna or vanity license plate yet, so I imagine the intersection of (Tesla owners) and (hams) might be very small

author: ejeffrey
author_rank: Super Contributor
timestamp: May 16, 2023, 03:03:49 pm
content: When I looked a couple years ago even a lot of home theater receivers were ditching AM radio. Given most of them take the anti-apple strategy of "why have 100 features when you could have 200" it seems like there is probably a real reason. It's certainly not impossible but a lot of manufacturers seem to think it's not worth it for a feature many people will never use.Cars are a different situation from home use given AM radios range and robustness to terrain obstacles as well as use as emergency radio but it's still not surprising to me that manufacturers are deciding it's easier to just ditch it than keep it working.