Digital Signals Spark Static From AM Radio 176
Carl Bialik writes "Digital radio is touted as broadcast radio's golden ticket, but the transition to digital broadcasts is creating static and interference for many smaller AM stations that are still analog-only, the Wall Street Journal reports: 'The AM stations most affected are those whose neighboring stations -- nearby on the dial -- add a digital signal.' The WSJ adds, 'For some small AM operators, it adds insult to injury that the only company licensing the digital broadcast technology is one backed by the small stations' deep-pocketed competitors.' Critics question why the FCC only approved the technology from that big radio-backed company, Ibiquity."
Comment removed (Score:3, Funny)
Re:Money money money... (Score:2)
There are a few good AM stations, but they are a small minority.
Re:Money money money... (Score:2)
If you goto a larger city and scope the NTSC/DTV spectrum you will see interferance on every channel. A friend just did a large job in chicago and told me all about it. This in theory, wasn't supposed to be as a big of a problem as it is. The good news, DTV receivers handle it quite well and it's only temporary.
All I can say to the AM folk...
At least they didn't force the upgrades on you and force you to pay for their "work in progress" digital sig
Ibiquitous static (Score:3, Funny)
Man, that Ibiquity seems to be all over the place these days.
Critics question why (Score:2, Insightful)
What about: 'Because they payed the most money and the FCC does not mind creating monopolies when properly greased.'
Once again, I am happy not to live over there, my middle of the road ideas would be considered ultra left wing in over there.
And why did the FCC not mandate digital PCS? (Score:2)
Re:And why did the FCC not mandate digital PCS? (Score:2)
Of course it probably would be better to let the market decide both issues.
Re:Critics question why (Score:2)
Re:Critics question why (Score:2)
But that is only the right wing majority that has played its card very well by getting hold of most media outlets. But that does not mean that there can be no-one with common sense and care for their fellow human beings.
Why Boeing is doing badly, compared to Airbus... (Score:2)
Re:Critics question why (Score:2)
http://www.marxist.com/ [marxist.com]
There's also P.O.W.E.R. but that's not an easy acronym to google for so I can't pull up a URI.
Just like HDTV (Score:1)
At any rate it seems like another way to fleece the public.
Anyway analog broadcasting should be preserved as they are easy to implment and use in the event of an emergency.
Re:Just like HDTV (Score:2, Informative)
I currently have a tv with built-in HDTV tuner and a plain-old VHF antenna. I also have cable from comcast. Whenever I can, I watch over-the-air HDTV instead of the cable (which I'm paying for) just because the quality is so much better.
(Why do I pay for cable then? 2 reasons, bundled with internet service, it's pretty cheap, and I get more statio
Re:What Does More Buy You? (Score:2)
So you have killer OTA HDTV.
But I don't see what's so *great* about having more when it generally means a plethora of re-runs, mundane cooking shows, and an automatic nipple of crap for kids to suck on.
Is it the whole watercooler, "Did you see show XYZ last night?" thing?
I pay $40/month for vaguely improved internet connection. If you put the difference between my 40/month bill and your total cable bill in the bank at the end
Re:What Does More Buy You? (Score:2)
1. Instead of buying CDs, buying MP3s, or even downloading music illegally, do you choose to tape your music on audio cassettes off of AM broadcasts?
2. Assuming the type of music you like is never played on the radio, do you get your music by hand-recording live shows on cassette tapes?
3. Do you prefer the sound of music on record players, because the natural filters and background scratch are how "music is supposed t
Re:What Does More Buy You? (Score:2)
Lost
Battlestar Galactica
Drawn Together
Rollergirls
Monk
Perhaps I'm wasting all my time doing this. Perhaps. But for the first time in 4-5 years I'm not playing an MMORPG or indeed any PC games (except ones released more than 20 years ago). Maybe watching TV is less stimulating for my brain, but then again I used my "free time" last night while watching TV to research
Re:What Does More Buy You? (Score:2)
Good luck on your changes to planning/zoning ordinances.
Re:What Does More Buy You? (Score:2)
I meant "new" in that there are new episodes airing. I don't actually watch it "new new", because it is on at the same time as Battlestar Galactica, and my DVR only has one tuner. I just recorded all the episodes on USA's New Year's Day marathon, and finished watching them last night.
Good luck on your changes to planning/zoning ordinances.
Thanks. Of course being on the city planning a
Re:Just like HDTV (Score:3, Informative)
IBOC (In Band On Channel) is both an analog and digital service. no changes in frequency, no adapters required for older radios.
It is efficient and higher quality and still free to the user, which is why even the shortwave broadcast bands are going digital.
It is in Ibiquity's interest to enco
Re:Just like HDTV (Score:2)
enhancements such as pro-logic surround sound.
Two points I would like to make about this.
First, Pro-Logic surround sound is a matrix system. It can be implemented wherever there are two separate channels of audio. Implement discrete surround and I will be impressed.
Second, once you have implemented it, what are you going to use for source material? Music, in general, is two-channel stereo. New recordings could be made in discrete surround, but what about the very large corpus of existing work?
Re:Just like HDTV (Score:3, Interesting)
Already existing broadband has pretty much caused shortwave broadcasters to start committing suicide. That's because they've forgotten the reason for their existance.
Shortwave broadcasting isn't supposed to be for distributing CD-quality music, it's supposed to be for distributing information over long distances to places that either don't have local information outlets or have restricted outlets. Analog works JUST FINE for that.
DRM (the curren
Re:Just like HDTV (Score:2)
Except... a lot of the MW and HF transmissions can circle the globe (especially at night and/or during the 11-year sunspot cycle). I can't even begin to imagine the massive interference...
Now, something like VHF between 50Mhz and 200MHz or so would let you go a hundred miles or so, without the global interference being a problem.
Re:Just like HDTV (Score:2, Informative)
(frequencies)
http://www.arrl.org/FandES/field/regulations/allo
(general)
http://www.arrl.org/hamradio.html [arrl.org]
I love you conservative shills... (Score:2)
But the real answer to your question is, "The difference is th
Don't have the time (Score:1)
Re:Don't have the time (Score:3, Funny)
Sounds like my DVD remote also operating my old TV (Score:2, Interesting)
Oddly enough, I have one of those "emergency" flashlights that would also change the channels on yet another ancient TV.
And in yet another case, we ha
Re:Sounds like my DVD remote also operating my old (Score:2)
Re:Sounds like my DVD remote also operating my old (Score:2)
Re:Sounds like my DVD remote also operating my old (Score:2)
I almost defy you to show me a house $200k around here that doesn't have one. Plus, this is
Re:Sounds like my DVD remote also operating my old (Score:2)
Just because it's common doesn't mean it's not lazy.
Since the fireplace is gas instead of wood-burning, there's just an IR sensor that turns on the gas.
See, lazy. You don't even have to chop and haul wood. What's the point? You don't get the wonderful smells of burning wood. You don't get a nice bed of coals for roasting marshmallows. You don't even get the satisfaction of starting a fire yourself. Starting the fire is more than half the fun of having
Re:Sounds like my DVD remote also operating my old (Score:2)
Back in my day you had to make the pen and paper out of twigs and papyrus, and if you ran out of ink you'd just jab it into your arm and use blood, and we liked it!
Cars? Don't get me started on cards.
Tough call for some of you (Score:2)
Re:Tough call for some of you (Score:2)
Re:Tough call for some of you (Score:2)
Re:Tough call for some of you (Score:2)
Re:Tough call for some of you (Score:2)
I'm also prejudice against evil, greed, hate, ignorance, murder, stealing, corruption and encouraging child-molestation through practices like abstinence and denial.
I suppose if you are not prejudiced against the latter group, you are quite likely to embrace the former.
Thanks, this really helped me understand some stuff. Mod the parent up!
Re:Tough call for some of you (Score:2)
You've just claimed to be ignorant, unreasonable, and/or irrational. From your post, I suspect you're correct in that claim.
False dilemma .... (Score:2)
How about prejudice against misuing the public radio frequencies?
I couldn't care less if it's Christian programming being stomped on, or Howard Stern. Of it Howard Stern was getting stomped on by Christian programming.
They should bloody well keep the radio waves working correctly without spilling over onto other frequenci
Re:False dilemma .... (Score:2)
New method for earning money as Clear Channel (Score:2)
1. Buy radio station neighbouring a competitor's band.
2. Broadcast FCC legal digital interference.
3. ???
4. Profit!
Major lawsuits coming? Anyone?
Re:New method for earning money as Clear Channel (Score:2)
Re:New method for earning money as Clear Channel (Score:2)
Digital AM quality issues... (Score:3, Informative)
Hopefully digital AM will get dropped as people realize how terrible it sounds.
FM, on the other hand, sounds great and doesn't have the sync problem.
If I can only figure out how to turn off the digital AM support in my stereo!!!
In case this is just a fluke, here are the details:
AM 740 in San Francisco.
Headunit: Kenwood KDC-890
Digital Box: Kenwood KTC-HR100
What "digital" radio is...and why it's bad (Score:2, Informative)
This "HD Radio" is actually called IBOC (in-band, on-channel). Radio works by changing the amplitude (AM) or the frequency (FM). You're only permitted to change it by a certain amount--your bandwidth--otherwise it will interfere with adjacent stations. By adding more information, the digital data stream, you're using increased bandwidth.
The other big issue with AM is overnight. Most AMs power down or sign off at sunset because the atomosphere changes overnight and AM travels mu
Ibiquity vs DRM - Digital Radio Mondiale (Score:3, Informative)
The AM MW mode should be left alone. The band that it is used in the US is not that reliable for digital modes, but it is very reliable for AM transmision to local areas.
This band/mode is essential for emergencies. Everyone in the US has an "AM" radio somewhere in the house or their car. It will just work.
Has the FCC rated this HD radio as an actual mode?
I have started to experiment with drm on my HF equipment and in fact i am upgrading to a SDR-1000 in a month or so.
With my existing equipment, I have heard a few of the DRM broadcasts on HF Shortwave and they are impressive. I have heard that you can broadcast it with a SDR-1000.
DRM is an open standard based on mpeg4. In fact this is the standard for european countries. There is GPL code for both listening and transmitting it.
http://en.wikipedia.org/wiki/Digital_Radio_Mondia
KB0FHF
Re:Ibiquity vs DRM - Digital Radio Mondiale (Score:2)
Now watch it get rated +5 interesting, and this get rated -1 offtopic...
Re:Ibiquity vs DRM - Digital Radio Mondiale (Score:2)
Re:Ibiquity vs DRM - Digital Radio Mondiale (Score:2)
HD Radio is in demand by AM stations that wish to improve the fidelity of their signals. On the FM side, it is being used more for delivering multichannel (aka "multicast").
Re:Ibiquity vs DRM - Digital Radio Mondiale (Score:2)
Ah, those Yankees (Score:2, Insightful)
The rest of the planet wisely chose a system that was entirely digital, and which consequently does not have these problems, while the Americans, defending the inalienable right to own radio stations using 1930s technology, or some such thing, fought for a system which sqeezes a digital audio stream into their existing AM or FM signals.
An all round bad idea, and
Re:Ah, those Yankees (Score:2)
Re:Ah, those Yankees (Score:3, Interesting)
I disagree. (Score:2)
This is not unusual in the US, in any area of technology. I've seen USians build major roads with nothing more than sand for a foundation - 2000AD cars running on 2000BC infrastructure. Sure, the roads break up badly, and I'm certain there are many accidents and deaths on US roads a
Re:I disagree. (Score:2)
In what state?
I was about to call BS on that, but then I remembered about this thing called "The South," and I thought maybe I'd check
Re:I disagree. (Score:2)
FM is also affected by IBOC interference (Score:2, Interesting)
In my experience, it also degrades the analog FM signal (of the IBOC broadcaster) with additional multipath.
It's sad that the FCC will go after 2 watt pirate broadcasters, but not care about interference on a much larger
Same reason (Score:2)
Heads need to roll at the FCC, they are not doing their job.
-- Bob
Monopoly (Score:2)
What's the Point? (Score:2)
Computer and entertainment devices are much worse (Score:2)
The question is... (Score:4, Informative)
Re:The question is... (Score:2)
Because the US needs an IBOC solution, which DAB isn't.
Besides, DAB isn't exactly taking the world by storm, as you imply. There are a lot of problems with the system (such as smaller stations having to depend on the largerones), which is making DRM (Digital Radio Mondiale) on 30MHz+ loo
Re:The question is... (Score:2)
Real Man's electricity, is 240v. If it ain't strong enough to electrocute, what's the use?
Re:The question is... (Score:2)
You can on 120V as well (and 50/60Hz doesn't change anything). In fact George Foreman-branded electric grills have been quite popular for some time.
The voltage really doesn't matter, it's voltage times current. I don't know what current your typical wall outlets can support, but 20 amps is pretty standard in the USA, and there are very, very few item
You want to know why the FCC blessed one method? (Score:4, Interesting)
uh, standardization... (Score:2)
Bit rates for digital radio... (Score:2)
AM: 32K bit
They use a codec similar to AAC.Re:Boo Hoo Hoo. (Score:2)
I wonder though, is this digital signal the stuff that identifies a radio station for new car radio displays?
Re:Boo Hoo Hoo. (Score:2)
Sounds like an awful idea. It's annoying when the station you're tuned into starts to fade as you drive along; I can't imagine being interrupted by all those sharp chirps and clicks that digital feeds make when they're interrupted.
Re:Boo Hoo Hoo. (Score:2, Informative)
Re:Boo Hoo Hoo. (Score:2, Interesting)
Re:Boo Hoo Hoo. (Score:2)
Re:Boo Hoo Hoo. (Score:2)
I see the digital broadcast can be simul-cast with analogue, but that it still interferes with neighbouring analogue signals. They can't even transmit digital at night legally.
Re:Maybe this is a wakeup call... (Score:2)
Also worth including on that list is the cc radio [amazon.com]. I've had very good luck with mine, going on about 4 years now. The digital tuning is a godsend and I can pick up distant (aka our local) TV audio quite clearly, even thought the video is unwatchable on a regular TV antenna.
I didn't know about the SuperRadio [radioshack.com] before but I'll go check one at at Radio Shack (hopefully they still have radios on displa
Re:Maybe this is a wakeup call... (Score:2)
Re:Maybe this is a wakeup call... (Score:2)
n0spamus actually replied [slashdot.org] with the Select-A-Tenna which is what I was thinking of.
C. Crane (Score:2)
C. Crane [ccrane.com] has a nice selection of antennas for AM, FM broadcast, SW and Wi-Fi.
The Boston Acoustics Recepter is worth a look as a first generation HD Radio. If you are serious about AM, this is the
Re:Maybe this is a wakeup call... (Score:2)
The GE Superradio III has kickass AM reception for a $50 radio. I use one at work and am delighted with it. Construction is cheap--for example, the battery cover is held on with duct tape, but key components are high-quality. Sound quality is admirable, particularly for AM signals.
Re:Maybe this is a wakeup call... (Score:2)
Just string a long piece of wire to a tree, and ground it properly.
Re:Maybe this is a wakeup call... (Score:2)
Yeah, but tuning the directionality of your wire is a pain in a snowstorm.
Re:Maybe this is a wakeup call... (Score:2)
Yes, thank you!
My biggest catch was WSB Atlanta from the San Francisco area.
Bravo! I never did that well with the store-bought Select-A-Tenna. Hmmm, maybe I ought to check out the back issue of Popular Mechanics.
Everything interferes with AM (Score:2)
Still, I enjoy fiddling with crystal radios etc and would hate to see the AM stations lost completely.
Re:bad protocal? (Score:2, Informative)
Digital AM radio uses over 50 KHz of bandwidth, so it is possible for a digital AM station to wipe out weaker stations 2 or even 3 channels away on either side of thier di
Modulation Theory 101 (Score:5, Informative)
Amplitude modulation, or more correctly double-sideband non-suppressed carrier amplitude modulation (FCC emission type A3E), results in an RF spectrum that is twice as wide as the highest frequency component of the modulating signal. In other words, if the signal you are modulating has as its highest frequency component 3kHz (normal voice signals), then the resulting AM signal will occupy 6 kHz of RF spectrum - from 3kHz below the nominal carrier frequency to 3 kHz above the nominal carrier.
Now, we have to consider the concept of "receiver bandwidth". A properly designed radio receiver will only pick up signals within a given frequency difference of where it is tuned (the "tuned frequency" or TF) - this is the receiver bandwidth (sometimes referred to as "IF bandwidth" since in modern superheterodyne receivers it is the bandwidth of the narrowest intermediate frequency section that determines the overall receiver bandwidth).
Now, consider the case of 2 radio stations spaced such that their carriers are 10 kHz apart - the normal spacing for AM radio stations. Assume your radio is tuned to one of the stations. If your radio has a receiver bandwidth of 20 kHz (in other words receiving signals from 10 kHz below tuned frequency to 10 kHz above tuned frequency), you would hear the station you *weren't* tuned to as a 10 kHz whine on your radio (the carrier of the other station, 10 kHz off your tuned frequency), plus the audio of the other station inverted in frequency (low tones become high tones and vise versa).
So, your radio has to have a narrow filter to receive only those signals within 5 kHz of tuned frequency (total 10 kHz). Now, a perfect "brick wall" filter would allow, say, 4 kHz through, but stop 4.00001 kHz dead. Now, filters are not perfect, and so if your filter allows signals from, say, 4 kHz away from TF, then it will not totally block signals until they are, say, 6 kHz from TF. So, radios are designed to allow signals +/- 3kHz from TF in (receiver bandwidth of 6kHz), and block signals more than 5 kHz from TF.
OK, now, how do we add any new signals to the A3E signal so that we can put the digital signal in place? We cannot place those signals within 3kHz of the carrier without going to a LOT of trouble, otherwise analog radios will "hear" the digital signal as noise. So what IBOC does is exploit that "no man's land" from 3kHz away from carrier to 5kHz away from carrier to put the digital signal in. Now, your old analog radio will still "hear" these signals to an extent, but between the attenuation of the receiver bandwidth and the attenuation of the audio chain, this noise will not be very perceptible.
HOWEVER - remember how I said there were no perfect "brick wall" filters? Well, that applies to transmitters too. The transmitter may be putting signal into the 3 kHz to 5 kHz region, but it will put some unwanted signals beyond 5kHz (they will just be very weak compared to the desired signals) - and that means into the frequency band of the next guy on the dial. However, if the next guy is far enough away in space, your signals that are in his band (which are already weak) will be weakened further by distance, and won't be perceptible by the other guy's listeners. Also, your signals that are in the 3kHz to 5kHz area will be weakened by distance, and attenuated by the receiver's filters, and so they, too, won't be very objectionable.
Except in the fringes between where your spatial region stops and his starts. That's what is happening here - if you are close to "the other guy" you won't hear the interference, but if you are far from him, and close to the digital station - you get noise where there was none before.
Add to this the fact that the stations that are going digital are the stations with money - and how do you get money? By having lots of listeners. How do you get lots of listeners? Among other things, by having lots of POWER <Tim Allen Grunt>. The little station
Re:Modulation Theory 101 (Score:2)
Phase modulation (Score:2)
Re:Modulation Theory 101 (Score:2)
Elementary economics tells us that nobody is going to buy a technology that interferes with their own signal, so it means that the technology will interfere with somebody else's.
By
Re:Modulation Theory 101 (Score:2)
Re:Modulation Theory 101 (Score:2)
Re:Modulation Theory 101 (Score:2)
The reason I suspect the signals you were listening to were pure digital is that Europe has
Re:Modulation Theory 101 (Score:2)
Re:Modulation Theory 101 (Score:2)
Although AM stations are limited to a nominal +/- 5 kHz modulation, I read an interview with a broadcast engineer a number of years ago who said that he just broadcast the
Re:Modulation Theory 101 (Score:2)
However, the other response is incorrect - you CANNOT put a modulating signal of more than 5kHz bandwidth onto an A3E carrier without exceeding 10 kHz bandwidth. Moreover, the emissions mask for an AM station (the frequency vs. amplitude plot they are not allowed to exceed) is not a sim
Re:Modulation Theory 101 (Score:2)
Now, given that in frequency space with regard to filters, everything is logarithmic b
Re:Modulation Theory 101 (Score:2)
The IFs of "traditional" radio designs are 455 kHz for broadcast AM radios (putting the adjacent channels at 445 and 465 kHz) and 10.7 MHz fo
Re:Modulation Theory 101 (Score:2)
In order to send a signal (voice/whatever), the amplitude of the carrier wave is modulated, only. So why would an amplitude modification of the signal cause it to have any additional frequency bandwidth?
thanks for
Re:Modulation Theory 101 (Score:2)
Let's consider carrier and audio signals that are sine waves of the same size:
carrier = sin(xt)
audio = sin(yt)
modulated = carrier * audio = sin(xt) * sin(yt)
x is the carrier frequency (large) and y is the audio frequency (small). (Yeah, yeah, I am sweeping a factor of 2*pi under the rug. Doesn't everybody calibrate their radio dial in radians per second?)
Using a simple trigonometric identi
Re:Digital or Digital? (Score:2)
It can't be RDS, as RDS
Re:AM Radio Interference (Score:2)