NRSC-3? RW article on AM bandwidth

[rbrucecarter5]

You've busted no myth. Where is YOUR test data to support your claim? Anyone can make idle chat about tech-specs. I saw the test results, as well as the test bed. Some of the best broadcast engineers in the business were involved, and they did so without bias.

I can tell you, since all 40+ radios sat in my office for a year, that there were many top-of-the-line models included. All receivers were measured, and broken into three groups, based upon performance. From there, further testing, and research was performed.

Calling your bluff:

Bratz radio / lamp / clock: model MGA 260844
Mary Kate and Ashley: model MKA12
Ultronic: model RR9901

I can get you a lot more model numbers, this was two minutes walking around the house and looking in the junk bin.

All cheap junk - the type kids go for, the type you find in dollar stores, given away for promotions, bargains at Walmart.

I can see the error made in your test methodology - you looked for high quality AM radios, when most people don't give a ___ about AM. I found as many models of cheap promotional stuff that didn't even have AM capability. I found several of those little scanning radios that don't even have a manual tuning knob. Just a volume control, scan button, reset button, and flashlight.

It is possible that "top of the line" models still use the old "three IF can" reference design, old reference designs die hard. But that is probably because there were fewer price constraints on a "top of the line" model. 5 minutes scanning semiconductor sites - and I came up with three reference designs - all minor variations of what I described originally. I found that ALL the old "three IF can" reference designs and the IC's that went with them are discontinued, not recommended for new design, etc. Maybe they can still be built in new radios, but the manufacturer would be doing lifetime buys, or buying from NTE! The new low part count reference designs (NOT IBOC) are the future of radio - get used to THAT!!! Unless you can find me some reference designs from semiconductor manufacturers that do AM right - I sure couldn't find any. In fact, I found a data sheet from Silicon Labs that has NO external components at all - one IC - AM ferrite bar - DONE. They even talk about using a PC board loop antenna to get rid of the ferrite bar. And they are NOT making an HD chip, but their chip DOES support RDS. So much for getting better performance by putting in better ceramic filters, they even eliminate the ceramic filters and tuning capacitor. Since they are right up the road from San Antonio, some of your high pressure marketing types better get up there and convince them - because if I had the design responsibility for a cheap radio, and faced with the 3 can design, the IC that needs tuning caps and ceramic filters, and the single chip - I'd go single chip every time. Better reliabilty - smaller. If that chip has HD in it, fine, if not - well the consumers don't care at this point anyway.

Reseach - with 41 hand picked people from Ibiquity no doubt. I am sorry, but the moment somebody from Ibiquity and early adopters of IBOC started saying that AM bandwidth should be reduced to lower interference - the credibility level was gone. It is too self serving to lower the playing field of all AM audio, justify it by "studies" done with "typical" radios show they don't have bandwidth anyway, etc. Its snake oil to me - without even trying hard I found three cheap junky AM radios with wide bandwidth (because they ARE cheap).

I don't have the time to go do tests on them at work - nobody is paying me for it. But when I can't hear a local 620 because of splatter from a local 660 - it is pretty obvious they are wide band. And - unfortunately - self jam on IBOC. Its real - and you guys better come up with a way around it or nobody will listen to a static filled mess.

 

[SirRoxalot]

Static-filled Mess

I don't have the time to go do tests on them at work - nobody is paying me for it. But when I can't hear a local 620 because of splatter from a local 660 - it is pretty obvious they are wide band. And - unfortunately - self jam on IBOC. Its real - and you guys better come up with a way around it or nobody will listen to a static filled mess.

So, what you're saying is that the most common radios on the market are so non-selective and wide-band that AM has become a hash-fest anyway? It seems to me that you have just made a strong argument for putting an end to the low-fidelity, monaural broadcasts on the AM band in favor of a system that will offer high-fidelity, stereo broadcasts.

Yes, digital will mean an end to long-distance listening. With the advent of Internet streaming, that may not matter much anyway. Will IBOC mean a clear, high-fidelity signal for the market that a broadcaster is intended to service? THAT'S the real question.

The AM band these days is full of noise - IBOC or not. Music programming is minimal, relegated to niche formats that can't draw enough listeners to interest even fringe FM signals. Non-music broadcasts - i.e. talk in its many varieties - don't require bandwidth beyond 7K anyway. To the generation of listeners under the age of 35, AM exists only if there's a sports broadcast that they can't get elsewhere.

Digital - be it IBOC or another technology - is a chance to resurrect a whole bandful of radio frequencies and offer expanded programming opportunities. And, as far as bandwidth is concerned, digital can get the job done with a lot less spectrum than analog. Ultimately, we could have more listenable channels available if digital broadcasting becomes a reality.

 

[rbrucecarter5]

Re: Static-filled Mess

So, what you're saying is that the most common radios on the market are so non-selective and wide-band that AM has become a hash-fest anyway? It seems to me that you have just made a strong argument for putting an end to the low-fidelity, monaural broadcasts on the AM band in favor of a system that will offer high-fidelity, stereo broadcasts.

Except for one thing - the band died years ago except for talk radio and sports. And those formats don't benefit from stereo or high fidelity. So why bother with AM-HD at all? Stereo musical beds? Stereo commercials? For that - the industry is willing to jam the entire band - possibly world wide? Might as well put the band out of its misery right now, because once nighttime IBOC fires up, unless you are a mile from the station, forget it. One continuous hash fest end to end on the AM band. Courtesy of the incompetance not only of the Ibiquity engineers, but now the FCC as well. If you think people don't listen to AM now, just tune across the band once nighttime IBOC fires up and hear for yourself how irritating it is. Even daytime, I have to turn the radio down when tuning across the hash, then turn it up once I'm on the station. That's how loud it is - on every radio. Not just one you no doubt will claim is defective.

Have you listened to AM-HD? Medium bandwidth streaming quality. Frequent phase distortion. Irritating - just like streaming audio. Listener fatigue after a few minutes. No way I'd convert to that awful sound if I owned a station. I'd be putting on wide bandwidth mono - or C-Quam because Sangean and possibly other manufacturers include it.

It is scary - the way people on here parrot what obviously is double speak from high pressure Ibiquity sales people. I'm hearing the same bovine excretion so often, I could almost re-assemble their power point presentation without even seeing it personally. Same high pressure sales techniques as insurance salesman or the ____ religious cults. It is scary how many otherwise intelligent people are buying it. To the detriment of their own audiences - and - not that many years after the AM stereo debacle. At least THAT was a working technology. Not defective like IBOC.

Boy - when this IBOC stuff self implodes from consumer apathy - the sad thing is that the industry will be absolutely littered with incredible cynics who, after seeing the failure of AM stereo, and the failure IBOC, will never again invest in some new technology that offers the hope of saving the band. That is the ultimate price of this defective technology.

The good thing about it - it will bankrupt the people who dreamed up the defective system in the first place. Unless they sell out and cash in before the excretion impacts the rotary ventilation device.

 

[OKCRadioGuy]

That my friend puts a whole new SPIN on CRAP CHANNEL!


;D

 

[FFoti1]

Reseach - with 41 hand picked people from Ibiquity no doubt. I am sorry, but the moment somebody from Ibiquity and early adopters of IBOC started saying that AM bandwidth should be reduced to lower interference - the credibility level was gone. It is too self serving to lower the playing field of all AM audio, justify it by "studies" done with "typical" radios show they don't have bandwidth anyway, etc. Its snake oil to me - without even trying hard I found three cheap junky AM radios with wide bandwidth (because they ARE cheap).

I don't have the time to go do tests on them at work - nobody is paying me for it. But when I can't hear a local 620 because of splatter from a local 660 - it is pretty obvious they are wide band. And - unfortunately - self jam on IBOC. Its real - and you guys better come up with a way around it or nobody will listen to a static filled mess.

Well, you've called no one's bluff, as you offered *ZERO* evidence to support your claims. Anyone can make adhoc commnets, as compared to verifiable comprehensive information that the group can evaluate.

CEA picked the radios, and there was no connection to iBiquity.

BTW: I didn't have any time to do testing either...but I did...AND...no one paid me. Thus, your weak excuses do not hold up. Unless you can offer data you can prove, save us all the bandwidth.

-Frank Foti

 

[al_atl]

R Bruce...
I could not agree with you more. A couple years ago I heard a 50KW-U station running IBAC at night. Maybe they forgot to turn it off, maybe they were testing it, but it obliterated everything +-30kHz. Their analog audio was so narrowed-down it was unlistenable, just like the Clear Channel AMs. Plus there was that annoying hiss in the background. No thanks. If IBAC AM is adopted in a big way, it will sell a lot of radios. I'll sell mine. As you said...wideband analog is the way to go for now. And I'd do it in CQUAM...there are a lot of cars out there with CQUAM in them...I happen to own two. I'd say the majority of my family members have CQUAM in their car. They don't know it, but it's there. Maybe they'd notice it if someone put some really nice, clean, well processed stereo audio on the air and opened up the bandwidth to the maximum. I know that on the rare occasion I hear such a station, it jumps out at me. And it doesn't have to be a music station to benefit from this. I've heard talk stations that had their promos, sweepers, music beds, commercials etc in stereo and it makes a difference. Sorry, I refuse to drink the Kool Aid.

 

[Givers]

adviously Clear Channel is doing something right they own radio stations. Plus I know most of you would love to work at Clear Channel do to the fact you don't have to beg for parts on every little thing. Or at least in Oklahoma you don't

 

[rbrucecarter5]

Well, you've called no one's bluff, as you offered *ZERO* evidence to support your claims. Anyone can make adhoc commnets, as compared to verifiable comprehensive information that the group can evaluate.

CEA picked the radios, and there was no connection to iBiquity.

BTW: I didn't have any time to do testing either...but I did...AND...no one paid me. Thus, your weak excuses do not hold up. Unless you can offer data you can prove, save us all the bandwidth.

-Frank Foti

I've proved one thing - you know NOTHING about receiver design.

I also seem to have a lot of company on here, there are people who have experienced the same thing as myself.

Observational evidence from DX'ers has been recognized for years by broadcasting professionals who use it as the first indication something is wrong at the transmitter site. So if you want to continue to insult and belittle people who are telling you there are problems with IBOC, go right ahead. But ignoring the problems will not make them go away. Remember - DX'ers are the ONLY hope IBOC has of telling people how to receive the signal out in the suburbs. Otherwise - the "advantages" of HD will not be heard and people will assume analog is the digital signal.

CEA is in support of IBOC - so they are hardly an unbiased group at this point. They can pick receivers and test subjects to support whatever conclusion they want to come to. I am reminded of another group that touted credentials and flaunted them - and who went around saying the bandwidth of a GE Superadio 3 was poor. I DID measure that one, I got their result when I put the radio in narrow mode - they did not even bother to switch it to wide mode. Sloppy engineering.

 

[FFoti1]

I've proved one thing - you know NOTHING about receiver design.

I also seem to have a lot of company on here, there are people who have experienced the same thing as myself.

Observational evidence from DX'ers has been recognized for years by broadcasting professionals who use it as the first indication something is wrong at the transmitter site. So if you want to continue to insult and belittle people who are telling you there are problems with IBOC, go right ahead. But ignoring the problems will not make them go away. Remember - DX'ers are the ONLY hope IBOC has of telling people how to receive the signal out in the suburbs. Otherwise - the "advantages" of HD will not be heard and people will assume analog is the digital signal.

CEA is in support of IBOC - so they are hardly an unbiased group at this point. They can pick receivers and test subjects to support whatever conclusion they want to come to. I am reminded of another group that touted credentials and flaunted them - and who went around saying the bandwidth of a GE Superadio 3 was poor. I DID measure that one, I got their result when I put the radio in narrow mode - they did not even bother to switch it to wide mode. Sloppy engineering.

None of my comment, or the group testing effort, had *anything* to do with ability to design receivers. This was not a 'receiver design' contest. All we did was to test receivers and report the findings. You choose not to support your claims with valid, comprehensive technical testing data that support your observations. Until you do so, your claims are unsubstantiated.

I've never said IBOC was perfect. YOU chose to put me in a 'camp' based upon a testing effort...and...the fact that I'm not about to jump onto the IBOC-bashing bus. I've said before, but you choose not to listen, if IBOC issues are validated through 'good engineering practice' then it will be a no-brainer.

Sadly, this discussion has reached a point where you need to throw out *anything* as rebuttal. You are obviously afraid to offer valid technical proof that the group can evaluate, or you do not know how.

 

[DudeFan]

If you read the whole study, it is far from a ringing endorsement of reducing bandwitdh to 5khz. Sure you might spin it that way, but the results show that contrary to some of the talk out there: 1) average folks can tell the difference of a narrowed bandwidth 2) on cheap or good radios.

 

[SirRoxalot]

Time to Move Forward

The bottom line is STILL the viability of the AM band. Yes, there are a few successful talk stations on the band, but for the most part it is lost frequency spectrum for the average listener.

Wideband, narrowband, or even CQUAM, music ain't working on AM. The number of AM listeners is a fraction of the number of FM listeners. Digital delivery is the only hope for the long run because it CAN assure quality delivery of music programming to the MSA.

As far as DX listening is concerned, the miniscule number of listeners is not an audience that any advertiser is interested in buying. So, you're serving a few listeners who are not contributing to your bottom line. What's the point in that?

It's time to step forward into the new millennium and put a signal on AM that can make it a viable band for the majority of listeners. In Canada, they're essentially abandoning AM and shoe-horning LP FMs into every conceivable slot on the dial. Let's turn that bandwidth into something viable on this side of the border instead of just allowing the vast majority of that slice of spectrum to languish in obscurity.

 

[rbrucecarter5]

None of my comment, or the group testing effort, had *anything* to do with ability to design receivers. This was not a 'receiver design' contest. All we did was to test receivers and report the findings. You choose not to support your claims with valid, comprehensive technical testing data that support your observations. Until you do so, your claims are unsubstantiated.

I've never said IBOC was perfect. YOU chose to put me in a 'camp' based upon a testing effort...and...the fact that I'm not about to jump onto the IBOC-bashing bus. I've said before, but you choose not to listen, if IBOC issues are validated through 'good engineering practice' then it will be a no-brainer.

Sadly, this discussion has reached a point where you need to throw out *anything* as rebuttal. You are obviously afraid to offer valid technical proof that the group can evaluate, or you do not know how.

The reason why I made the statement you know nothing about receiver design is that - if you did - even though you are an ardent supporter of IBOC: you would immediately realize - "Oops. He's right - the things WILL self jam!" I've heard it - those little one inch speakers are terrifically good tweeters and - if you think 10 kHz heterodyne is annoying, just WAIT until you hear IBOC sidebands through those tweeters - now the entire spectrum from 10 kHz to 15 kHz is filled with screeching noise!

OK - you think you are calling my bluff. I guess I'll have to get on the ball and start taking measurements to prove the things I've said. I need to digitize IBOC hash from +15 to -15 kHz, including the warbling noise on frequency. I think I can use photobucket for sound files - no way I'm going to make IBOC sound better by making it MP3, it needs to be a .wav. I'll post the reference design schematics - both the old ones with three IF cans, and the new ones with a single, sloppy AM ceramic filter, along with as many spectral plots as I can find.

It may take me some time, but I can prove every statement I made about IBOC on here. Somehow, though, I don't think even proof will satisfy you.

 

[rbrucecarter5]

Re: Time to Move Forward

The bottom line is STILL the viability of the AM band. Yes, there are a few successful talk stations on the band, but for the most part it is lost frequency spectrum for the average listener.

So how is jamming the whole band from top to bottom going to improve the economic bottom line of the band?

Sound was GREAT on AMAX stations running AM stereo - so neither good bandwidth nor stereo helped the economics. Your scheme of IBOC brings nothing more to the plate - and simultaneously requires the purchase of very expensive radios! Hasn't anybody learned anything from the collapse of AMAX and AM stereo?

The problem with economic viability on the AM band is the PROGRAMMING. Put something on the air people want to hear, and they WILL listen. Here are the new stations that have come on the air on AM in my area:

Catholic masses - BORRRRRR-RING!!!!
Catholic preaching hymns - now THERE is some exciting music - NOT!
Who knows what Asian language - OK that ethnic group listens.
Yet another Asian language
Southern gospel - you GOT to be kidding!
Yet another Spanish
And another Spanish
And another Spanish

--- a band filled with irrelevancies to me. Some of them even in IBOC. I am underwhelmed.

Same problem with HD-2's on FM

Gay radio - now there is a thrilling concept - not
All Beatles all the time - 200 song playist - BLEAH I'm so burned out on that stuff I could puke
Spanish top 40 - I don't speak Spanish

I'm supposed to pay $200 for each radio to listen to that stuff? I don't even want to turn on my existing radio to hear the other stations they are formatted so badly.

HD radio - does it stand for "Hurling Dung" - because that is what the formats are to me. Excretion.

If radio wants to survive, do some formats like XM and Sirius. I can get excited about some of their formats - original, creative stuff. Along with higher quality versions of what I get now. All in digital sound. I pay for cable - when my radio is jammed top to bottom I guess I'll have to pay for radio as well.

Until then - the HD folks can take their "gay Catholic foreign language 200 song playlist" formats and go broke for all I care. I won't be listening.

 

[FFoti1]

The reason why I made the statement you know nothing about receiver design is that - if you did - even though you are an ardent supporter of IBOC: you would immediately realize - "Oops. He's right - the things WILL self jam!" I've heard it - those little one inch speakers are terrifically good tweeters and - if you think 10 kHz heterodyne is annoying, just WAIT until you hear IBOC sidebands through those tweeters - now the entire spectrum from 10 kHz to 15 kHz is filled with screeching noise!

Never said, or implied that I'm an ardent supporter of IBOC. You deduced that through your own bias. Just becase I did testing, does not make me a supporter of anything...pro or con. You're choosing to fight with the wrong guy. I've called your observations under question, but that does not mean I'm a supporter of one over the other. Just because I'm reticent to jump onto your non-supported claims does not make me the bad guy.

Your position would be further supported with valid, comprehensive test criteria to support your views, instead of making false personal claims against another.

 

[BofH]

To try and turn this dialogue into a constructive analysis of currently available AM receivers - Frank is there somewhere we can download the testing methodolgy?

A price point of say $50 should be chosen, to represent the average consumer spend on a new portable radio/cd/boombox unit (unless someone has a better figure)

Ideally all radio's currently available on the market should be purchased (that fit under this pricepoint, or as many as practical), then tested for bandwidth, selectivity, sensitivity etc on both AM and FM.

The easiest way to do this would be to setup a website with a forum that allows interested parties to sign up and volunteer a photo and measurements of each radio they purchase. A simple database could be scripted that allows model numbers to be searched etc.

I think this is the only way an accurate picture can be formed of the quality of radios now being sold in the marketplace.

Of course car stereos should also be tested, but generally speaking they have better quality radios than most boomboxes/portable units (at least OEM units anyway)

Matt

 

[FFoti1]

To try and turn this dialogue into a constructive analysis of currently available AM receivers - Frank is there somewhere we can download the testing methodolgy?

http://nrscstandards.org/AMB/AMSTG report summary.pdf

 

[Tom Wells]

The testing methodology does not mention the signal strength of the AM signals used in these tests.
The AVC makes a huge difference in perceived bandwidth.
Neither is there mention of whether these radios are digitally tuned, analog tuned, or how they were tuned if analog.
There is no mention of processing or the bandwidth of the original information.

It is very easy to a design a radio with a bandwidth which will satisfy most people.
You make the radio have about 15 kc of IF bandwidth with sharp skirts.
If you want 7 khz audio, you center tune. If you want higher audio, you side tune.
If you side tune by 7 khz, you'd be able to receive either upper or lower sideband info to 15 khz.
If you can't figure out how to tune an AM radio properly, you should go to FM, CDs or ipods.

For those of you about to say "distortion", go re-read chapters 1 and 2 of Modulation 101.
As long as the carrier and one sideband are in the receiver IF passband, there is no distortion.

Limiting bandwidth is frequency distortion. It is only to be defined whether or not a situation is appropriate for
limited bandwidth. 40-meter AM phone conversations are decidedly improved by limited bandwidth at the receiver.
AM MW public broadcast is not served well by a reduction to communications level audio.

By not representing America's radios accurately, this study exposes its bias.
They choose only to show that our current choices of radios are mostly limited to low quality.
As others accurately point out, this cheapness often results in extended high-frequency response.

The study does not mention whether or not consumers have a preference for audio with high-pitched hissing
when combined with analog info to 5, 7, or 10 khz. Is it better to have hissing with 5khz audio, or 5khz audio with no hissing?

By not stating testing methodology, it is clearly an "opinion piece" showing what they want to show.

They really should have stated that regardless of modulation response, all listeners showed a decided preference
for audio with a stong hiss from 7 to 14 khz.

Most people can't tell that ibiquity is stealing something from them, but they can hear that their radio doesn't
sound as good anymore. Or maybe they question their memory, this is what ibiquity wants.

 

[FFoti1]

The testing methodology does not mention the signal strength of the AM signals used in these tests.

The posted link is to the NRSC summary. If you wish for the draft of the actual methodology, you should contact NRSC directly for it. All of the items you mention were taken into consideration.

The purpose of the testing was to have a look back at the viability of the 10kHz NRSC response that was adopted 20 years ago. If you'd like NRSC to perform a study, as you describe, then please bring it to the NRSC for consideration.

I sense that many are reading more into this, then it is. If you wish to prove or disprove AM response due to the IBOC hiss, then that's a seperate study altogether. Trying to morph this set of tests into a topic that the testing was not meant for, is not correct, and is misrepresentative of the work performed.