AM analog wide vs. narrow (airchecks)

[LinoNYC]

For those who don't want to deal with big files, you may be excused ;-)

First we have a wideband .wav recorded from the am section of a KLH 12. Starting at WFAN (iboc on) then on to WOR (iboc on) on to short stop at WHLI (music 740) then WABC (iboc on) then WNYC (iboc off) and WCBS (iboc on) on this last one you'll hear the annoying "scratchy" distortion that plagues some iboc station's analog but not others. Note also Wcbs is using those cool retro sounders for their 40th anniversary.

http://www.sendspace.com/file/8oawb7 27MB

Then the line outs of a Bose acoustic wave radio (1999 build) typical narrow band, line up is WFAN WOR WABC WNYC WCBS-am.

While WABC clearly has the widest bandwidth, even with iboc, the difference is barely noticeable with the narrow radio.

http://www.sendspace.com/file/y28hmu 16MB

Lino

 

[SUPERCASTER]

This brief test (done by you) of a few radio stations at one location (yours) and with two radios (also yours) is supposed to prove everyone else's HD radio experiences, complaints and reception reports are false?
Your test is almost as complete as the 4 radio test used by iBiquity to convince the FCC that HD radio was the greatest thing since the invention of wireless, and would be the salvation of broadcasting. Or was it misrepresentations, politics, influence, money and lobbyists that did the trick?

I listen to a non-HD analog high fidelity, wideband AM station in wideband mode on my GE Superradio and it sounds great! Much better then HD-AM and it's low bitrate artifacts. Almost like FM.
However, on the same radio, analog reception makes HD AM stations sound like a hissy, noisy, fuzzy phone call.

 

[MotoMuzak]

"I listen to a[n]...analog high fidelity, wideband AM station...and it sounds great!"

My god......do they even make stations like that any more??

 

[LinoNYC]

This brief test (done by you) of a few radio stations at one location (yours) and with two radios (also yours) is supposed to prove everyone else's HD radio experiences, complaints and reception reports are false?

They represent real-world experience on average radios including one that is clearly wider band (KLH) than average, it shows that if the station is center tuned the hash is nulled. It also showed the annoying "scratchy" distortion on WCBS-am.

I've brought actual examples, pro and con concerning iboc on this and other threads, what have you brought?[EDIT]

Lino


[EDIT-inflammatory]

 

[SUPERCASTER]

This brief test (done by you) of a few radio stations at one location (yours) and with two radios (also yours) is supposed to prove everyone else's HD radio experiences, complaints and reception reports are false?

They represent real-world experience on average radios including one that is clearly wider band (KLH) than average, it shows that if the station is center tuned the hash is nulled. It also showed the annoying "scratchy" distortion on WCBS-am.

I've brought actual examples, pro and con concerning iboc on this and other threads, what have you brought?[EDIT]

Lino
[EDIT-inflammatory]

The HD-AM tertiary signal is -26 db directly under the main analog carrier and modulation. Many here are reporting that they pick up hash from the digital sidebands and/or the tertiary digital modulation. You claim otherwise.
[EDIT] Your "actual examples" are extremely limited, apply to you alone, and do not necessarily supercede others experiences with their radios at their locations.


[EDIT-inflammatory]

 

[LinoNYC]

The HD-AM tertiary signal is -26 db directly under the main analog carrier and modulation.

Given that a strong local and interference-free AM is lucky to achieve 30db/s-n your point is another of your red herrings. The airchecks I posted showed that even a wideband set tuned properly will effective null iboc hash. Digital tuning does this automatically.

[EDIT]

Your "actual examples" are extremely limited, apply to you alone, and do not necessarily supercede others experiences with their radios at their locations.

[EDIT]

Lino


[EDIT-inflammatory]

 

[scanman1]

For those who don't want to deal with big files, you may be excused ;-)

First we have a wideband .wav recorded from the am section of a KLH 12. Starting at WFAN (iboc on) then on to WOR (iboc on) on to short stop at WHLI (music 740) then WABC (iboc on) then WNYC (iboc off) and WCBS (iboc on) on this last one you'll hear the annoying "scratchy" distortion that plagues some iboc station's analog but not others. Note also Wcbs is using those cool retro sounders for their 40th anniversary.

http://www.sendspace.com/file/8oawb7 27MB

Then the line outs of a Bose acoustic wave radio (1999 build) typical narrow band, line up is WFAN WOR WABC WNYC WCBS-am.

While WABC clearly has the widest bandwidth, even with iboc, the difference is barely noticeable with the narrow radio.

http://www.sendspace.com/file/y28hmu 16MB

Lino

LOL There is no problem hearing those famous digital sidebands in your example, on the stations that are using them, whether set to wide or narrow band (although in narrow band, they are slightly less audible). 8)

 

[Tom Wells]

That's wideband allright! You have done an excellent job of showing that perfect center tuning does NOT cancel the sidebands.
There's more hiss in this recording than those provided by RF Burns.

I belive ibiquity has implemented a newer, lower noise method on the 50kw AMs in Chicago.
They now have less hiss, and better defined analog cripsness than 3 weeks ago.
They also seem to have less hiss when driving around when the sidebands don't stay balanced.

Has anyone else heard this change?

 

[LinoNYC]

That's wideband allright! You have done an excellent job of showing that perfect center tuning does NOT cancel the sidebands.
There's more hiss in this recording than those provided by RF Burns.

I have not heard Mr "Burns" audio ( I have a good idea who he is) Let's keep things honest and real.

Both posted airchecks show the noise floor well below normal listening level when center tuned. These are from strong local signals, with average ambient interference AM listeners are lucky to hear a 15db/s-n, IBOC hiss is the least of the problem.

My total investment here is a $120 radio which works well given the limitations I have expressed in other threads.

The engineer from Boston, and others feel that this sytem will hit the rocks of consumer apathy, I tend to agree unless the next generation of chips permit it to be embedded into common radios.

Gotta ask the skeptics what do you propose as an alternative?

AM's viability with young (under30) listeners is near-zero. That means it's future is doomed as the current audience ages out and dies off.

Something drastic has to be done to improve the perceived quality of AM. Period.

While I still prefer wideband AM, digital broadcasting will eventually become dominant throught the world, it's pointless to debate analog systems that had their day upwards of twenty years ago.

With the demographics issue looming the fact the some AM stations may find their outer service area somewhat truncated pales compared to the train wreck that is coming with the next ten years.

IBOC offers a degree of fidelity improvement on AM compared to what most people now hear, and for FM better performance and the potential to compete for specialty audiences (ethnic etc) that will soon be served by wi-fi in major cities.

Lino

 

[Tom Wells]

I am being completely honest about the level of hiss. The wide(r)band detector and audio circuit of the radio you used
shows the problem better. There is no more hiss in the analog signals presented, you have just provided a very truthful example.
I was able to greatly clean up the hiss in the RF Burns recordings by using eq and a variable-upper end cutoff filter.

I could clean these up as well, but that's not the point. Others can't, I certainly wouldn't want to add such processing to every radio I own, nor would it be practical.
That may be below the noise level suffered in a dense highrise metropolis, but not for most of us.
People have always been free to buy a better radio if they wanted better performance.
These are now the people who suffer most from the AM HD self-interference.

I propose letting the AM be itself and to h-e-double toothpicks with all the predictions of AM's certain doom.
Adding this level of hissing self interference has certainly lowered my TSL.



But, recently there is some hope that ibiquity has heard the complaint of poor intelligibility on the analog 5khz.

Your and RF's examples both present an AM mode I believe ibiquity is moving away from.
The big AM ibocs in Chicago now have less hiss and better sideband balance, better analog brilliance, the "pink noise" is now "white noise",
the sideband imbalances while traveling don't translate into as much noise.
They seem to have moved sidebands out to higher frequencies, permitting better brilliance.
Or they have acoustically fooled us into hearing higher sounds by emphasizing the fundamentals better.
It is much easier to listen to than the former mode, where the hiss was undeniable at any listening level, and the
crippled high end made it hard to distinguish words.


I will not address the issue of what programming changes would "help" AM, as the industry has been doing everything
the way I wouldn't have for the past 30 years. I defer to the consultants, who surely know best, as they are in the
business of knowing what people want.

 

[JohnnyElectron]

Find me an AM HD radio signal that sounds as good as these analog AM radio soundbites, and then I'll be sold on HD!
Listen here: http://www.fanfare.com/soundbites.html

Nice-sounding stuff, day and night, and no adjacent channel interference - and these are AM - with better stereo imaging than FM, IMO.

 

[dbdigital]

Find me an AM HD radio signal that sounds as good as these analog AM radio soundbites, and then I'll be sold on HD!
Listen here: http://www.fanfare.com/soundbites.html

Nice-sounding stuff, day and night, and no adjacent channel interference - and these are AM - with better stereo imaging than FM, IMO.

Sounds even better through headphones. But you can see why many radio enthusiasts and engineers alike refuse to give up the ghost on AM stereo. Totally FCC compliant and approved, fits an AM channel's limited bandwidth, inexpensive to convert a station: http://www.deltaelectronics.com/data/ase2data.htm and when properly engineered can sound amazing.

db