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The end of AM radio in your car?

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Re: The end of AM radio in your car?

#41

Post by Fatnino »

RF_Enthusiast wrote: post #35
stu2010 wrote: post #14

I haven't seen much discussion about how AM gets used for local road condition or emergency communication. When you're driving and see a sign that says "TUNE TO 1610 AM" and the car has no AM receiver, what do you do? This may be a shrinking niche, but it's potentially a last bastion of AM radio usefulness.

Those low power highway information stations are actually required to be low quality audio [1]. My understanding is that back in the day, broadcasters insisted that these stations were low quality so they would not compete with commercial broadcasters. In my opinion, those stations actually make AM seem much worse than it really is. That scheme backfired in the long run. [1] 47 CFR 90.242(b)(8) https://www.ecfr.gov/c…

There was (is?) a commercial station in the bay area that broadcasts simultaneously on AM and FM. I could tune the car radio to the correct frequency on each and then compare the sound quality by flipping the AM/FM switch.

FM is WAY better sound quality. It's not even close.

Re: The end of AM radio in your car?

#42

Post by Fatnino »

toss1 wrote: post #4
guywithahat wrote: post #2

This is the most interestingly line from his letter: > nearly 90 percent of Americans ages 12 and older — totaling hundreds of millions of people — listened to AM or FM radio each week, higher than the percentage that watch television (56 percent) or own a computer (77 percent) Admittedly it seems dubious but if true I'm surprised by basically every one of these numbers

Note the "listened to AM OR FM radio each week", emphasis on the "or". I can't say how long it has been since I checked the AM dial while driving (basically hit it by accident), but years it he most appropriate unit. What I heard (northeastern US) seemed to support some data I read that it is mostly taken over by religious and Limbaugh-type right-wing talk radio. So, that strongly left- Sen. Markey is supporting it s…

San Francisco used to have a station with left wing talk show hosts.

Then some big corpo (cumulus?) snapped up the station and the cast changed significantly, with the station swinging to the right very noticeably.

I switched it off permanently soon after. This was around the time I discovered I get more useful traffic information from my phone anyway.

Re: The end of AM radio in your car?

#43

Post by tjohns »

Fatnino wrote: post #41
RF_Enthusiast wrote: post #35

Earlier quoted context omitted.

Those low power highway information stations are actually required to be low quality audio [1]. My understanding is that back in the day, broadcasters insisted that these stations were low quality so they would not compete with commercial broadcasters. In my opinion, those stations actually make AM seem much worse than it really is. That scheme backfired in the long run. [1] 47 CFR 90.242(b)(8) https://www.ecfr.gov/c…

There was (is?) a commercial station in the bay area that broadcasts simultaneously on AM and FM. I could tune the car radio to the correct frequency on each and then compare the sound quality by flipping the AM/FM switch. FM is WAY better sound quality. It's not even close.

You're talking apples and oranges.

FM is absolutely better sound quality than AM. That's why music is mostly on FM. (On the other hand, AM uses less bandwidth and travels farther, since it's in the MF band and can bounce off the ionosphere. That's the tradeoff.)

At the same time, the highway information stations the parent poster is talking about are low power AM stations designed to play a road condition message within a distance of 3-5 miles from the antenna. The audio is often very poor quality, even for AM, because of the transmit power restrictions placed on them.

That said, it's worth noting the places you need these highway information stations most are also often places with some of the worst cellular coverage. If you drive in the mountains, they can be essential.

Re: The end of AM radio in your car?

#44

Post by tjohns »

Analemma_ wrote: post #30
stu2010 wrote: post #14

I haven't seen much discussion about how AM gets used for local road condition or emergency communication. When you're driving and see a sign that says "TUNE TO 1610 AM" and the car has no AM receiver, what do you do? This may be a shrinking niche, but it's potentially a last bastion of AM radio usefulness.

In a sample size of maybe 10, every time I’ve seen one of those highway signs and tuned to the station, the quality was so bad I couldn’t make out any words and so got no useful information. If that’s the last bastion of AM usefulness, scrap it and give that spectrum to the wireless carriers. Frankly, for stuff like road closure information I’m a lot more likely to get that from Waze (delivered over a 5G connection)…

The wireless carriers wouldn't be able to do anything with the AM broadcast band. It's in the MF range - not useful for cellular at all due to limited bandwidth, giant antenna requirements, and ionospheric bounce.

Re: The end of AM radio in your car?

#45

Post by tjohns »

olyjohn wrote: post #15
dctoedt wrote: post #9

AM radio broadcasts can reach somewhat farther than FM (and way farther at night on clear channels); that might matter in an emergency. As a middle-schooler living in the Washington DC area, I would regularly pick up WLS in Chicago, some 700 miles away, on my little crystal set at night.

From the Portland area, I could pick up KGO from San Fransisco at night. Never cared for the content as a kid, but it was still fascinating!

If you're not familiar with the term, look up "clear-channel station". (Not to be confused with the advertising company of the same name.)

https://en.wikipedia.org/wiki/Clear-channel_station

https://worldradiohistory.com/Archive-Station-Albums/WSM/Cle...

Stations like KGO receive special status to protect against interference, and in return are required to transmit 10,000 Watts minimum. Most transmit at 50,000 Watts. The idea was to make sure even the most remote parts of the country with no local stations would be able to receive one of the clear-channel stations at night.

Re: The end of AM radio in your car?

#46

Post by lormayna »

audiofish wrote: post #24
lormayna wrote: post #21

Earlier quoted context omitted.

I am an huge fan of DRM, but the lack of receivers it's a good limitation for that.

That is true, although I know of one company close to production of a <10$ module for OEMs to integrate.

This will be fantastic. I am looking forward to it!

Re: The end of AM radio in your car?

#47

Post by mgkuhn »

What exactly does he technically want to preserve? Does he really care about amplitude modulation? Or does he care about the frequency band (medium wave, HF) and its propagation properties? Or does he care bout the geographic reach of these stations?

Amplitude modulation is a historically important technology, because it was technically very simple to receive in the early history of radio, and because it was more bandwidth-efficient than FM. But it remains utterly badly suited for mobile reception, because it is highly sensitive for multi-path interference (unlike FM).

We have now far better modern, digital modulation schemes, including DAB and DVB-T2 for VHF and DRM for long, medium, and short-wave transmission. They provide (thanks to OFDM) much better audio quality and interference resistance than the old analogue modulation schemes, and they are also far more power efficient, which substantially reduces the enormous electricity bills of the transmitter stations. They also are very bandwidth efficient, and can be used in single-frequency networks.

Re: The end of AM radio in your car?

#48

Post by zikduruqe »

Fatnino wrote: post #41
RF_Enthusiast wrote: post #35

Earlier quoted context omitted.

Those low power highway information stations are actually required to be low quality audio [1]. My understanding is that back in the day, broadcasters insisted that these stations were low quality so they would not compete with commercial broadcasters. In my opinion, those stations actually make AM seem much worse than it really is. That scheme backfired in the long run. [1] 47 CFR 90.242(b)(8) https://www.ecfr.gov/c…

There was (is?) a commercial station in the bay area that broadcasts simultaneously on AM and FM. I could tune the car radio to the correct frequency on each and then compare the sound quality by flipping the AM/FM switch. FM is WAY better sound quality. It's not even close.

But, if you ever hear AM Stereo you'd be amazed.

Re: The end of AM radio in your car?

#49

Post by supermatt »

Fatnino wrote: post #41
RF_Enthusiast wrote: post #35

Earlier quoted context omitted.

Those low power highway information stations are actually required to be low quality audio [1]. My understanding is that back in the day, broadcasters insisted that these stations were low quality so they would not compete with commercial broadcasters. In my opinion, those stations actually make AM seem much worse than it really is. That scheme backfired in the long run. [1] 47 CFR 90.242(b)(8) https://www.ecfr.gov/c…

There was (is?) a commercial station in the bay area that broadcasts simultaneously on AM and FM. I could tune the car radio to the correct frequency on each and then compare the sound quality by flipping the AM/FM switch. FM is WAY better sound quality. It's not even close.

Although FM has a higher bandwidth, from a listeners perspective its more likely that you were experiencing a narrowband monaural AM - hence the massive difference to your ear.

Stereo or wideband AM is much clearer:

http://www.amstereo.org/sound.htm

Re: The end of AM radio in your car?

#50

Post by quickthrower2 »

stu2010 wrote: post #14

I haven't seen much discussion about how AM gets used for local road condition or emergency communication. When you're driving and see a sign that says "TUNE TO 1610 AM" and the car has no AM receiver, what do you do? This may be a shrinking niche, but it's potentially a last bastion of AM radio usefulness.

Tunnels near me just say "Turn on your radio" and blast the whole FM spectrum at least (might try it with AM too!). Guess you can do this in a tunnel!
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