IBUZ; therefore, I am

[4CX1000A]

I'm in the Binghamton, NY area today. Coming into town last night I punched up KDKA (Pittsburgh) to see if it was being drowned by IBOC noise from WBZ, as some folks have claimed. The answer is: not everywhere. There are places where KDKA comes in loud and clear, and others where all I could hear was IBOC noise. There was also IBOC noise on 1040, suggesting it was indeed from WBZ, a station that puts a strong signal into upstate NY most evenings.

This comes on the heel of discovering, through accidentally pushing my preset for WTSN (Dover, NH) in Norwood the other day, that WMKI 1260 is also running IBOC.

My question is this: why is any AM station running IBOC? There are no HD-2 channels available on AM, no additional revenue streams, and essentially no radios. There's no one who can hear the IBOC who cannot equally well hear the AM. So, why do IBOC at all? If WBZ and WMKI had instead spent their hundred thousand dollars to build gold plated statues of Fred Flintstone in front of their studio buildings, it seems to me they would got just as good returns on their investments.

I must be missing something. What is it?

 

[Schuyler]

Only all the hype before this dumb system was implemented.

And IIRC, IBUZ for AM doesn't even give you stereo. PHOOEY!

 

[faderraider]

If WBZ and WMKI had instead spent their hundred thousand dollars to build gold plated statues of Fred Flintstone in front of their studio buildings, it seems to me they would got just as good returns on their investments.

I must be missing something. What is it?
[/quote 

A statue of Barney? 

 

[DanStrassberg]

And IIRC, IBUZ for AM doesn't even give you stereo. PHOOEY!

Sorry, but you don't RC;>) AM-band IBOC IS in stereo, IF you are able to pick up an IBOC signal. The IBOC is, IIRC, at 1% of the analog carrier's nominal power, which means that the receiver has to be quite sensitive if it's going to flip to IBOC mode. Amazing, though, how those OFDM (stands for orthogonal frequency-division multiplexed) IBOC carriers can produce such loud hiss at 1% of the analog carrier power. Most likely, that phenomenon is at least in part a result of different methods for calculating the analog and digital power. Maybe somebody else can explain that. Bob Savage, are you lurking here?

 

[WNTIRadio]

As bad as WMKI sounds in analog, it does sound pretty good in digital. Same for WBZ. Unfortunately, the frequencies that AM is on don't lend themselves to digital broadcasting very well, especially at night. At least digital broadcasting in the sense of IBOC. First, you splatter your neighbors. Second, the power level is very low. And third, nighttime is a mess with IBOC, as evidenced by the original poster. Because of skywave and the phase cancellations and signal fading, you can't get a decent lock on a skywave AM on IBOC, and you can't hear it's analog neighbor.

IF AM were to go all digital, with everybody transmitting on their licensed frequencies, it may work. But that assumes that anyone besides engineers, station staff and a handful of radio geeks has an HD radio to hear it.

Move AM to channels 5&6, give them power outputs equivalent to their current coverage as best can be matched. WABC in NY can run 100kW, for example. Make the new band be able to support class C stations no matter the region.

Of course that will never happen because the FM stations now don't want AM to be on parity with them and compete for the same younger crowd and revenue.

 

[radiogooroo]

With all of the noise impacting AM stations these days, even the 50 kW blowtorches, I'm amazed any of you can discern IBOC noise from the rest of it. When power line and traffic light interference cause the local 50 kW station to completely disappear in my car on my drive home everyday, IBOC is the least of my concerns.

It's much more listenable on a sister FM's HD3 channel than it is on the AM band, and this station suffers no interference from other IBOC operations.

 

[Uncle Kaimbridge]

Amazing, though, how those OFDM (stands for orthogonal frequency-division multiplexed) IBOC carriers can produce such loud hiss at 1% of the analog carrier power. Most likely, that phenomenon is at least in part a result of different methods for calculating the analog and digital power. Maybe somebody else can explain that.

If you listen carefully to the "digital roar", you can hear the same digital sideband buzz you hear on an FM IBOC signal.
I suspect what that "roar" is, is just adjacent channel AM splatter you get with any nearby signal (in this case to the digital buzz).
And the thing is, I think it can be attenuated, at least to some
degree: If you listen next to, say WEZE (0.590), when they are airing an "auditorium sermon", sometimes there will be no splatter when nothing is being said, while other times there will be a steady loud roar/splatter——sounding just like the IBOC roar——again, when nothing is being said, but you may be able to hear something quiet but steady in the background (like an air conditioner or something, or even just a loud mic input).
I wonder if there is a way to manipulate or present the IBOC signal/hiss in such a way that the actual splatter can be minimized?

 

[DanStrassberg]

If you listen next to, say WEZE (0.590), when they are airing an "auditorium sermon", sometimes there will be no splatter when nothing is being said, while other times there will be a steady loud roar/splatter——sounding just like the IBOC roar——again, when nothing is being said...

Are you saying--or suggesting--that WEZE is running IBOC? I haven't checked for the hiss, but if it was there, I failed to notice it. And remember that WEZE is owned by Salem Communications. Salem is a major AM group owner. In fact, I would not be surprised to learn that, of all of Salem's full-power stations (AM and FM) a larger percentage are AMs than are those of any other major US group owner. I believe that Salem has made a commitment NOT to run IBOC on any of its AM properties for the time being.

 

[Uncle Kaimbridge]

If you listen next to, say WEZE (0.590), when they are airing an “auditorium sermon”, sometimes there will be no splatter when nothing is being said, while other times there will be a steady loud roar/splatter——sounding just like the IBOC roar——again, when nothing is being said...

Are you saying--or suggesting--that WEZE is running IBOC? I haven't checked for the hiss, but if it was there, I failed to notice it.

Absolutely not!
I’m saying, if you listen to their adjacent frequency “AM splatter”, during the quiet moments of an “auditorium sermon”, it sometimes sounds just like AM IBOC roar. It is nothing special about WEZE, it is just their programming provides the situation.

 

[JIBGUY]

My question is this: why is any AM station running IBOC? There are no HD-2 channels available on AM, no additional revenue streams, and essentially no radios. There's no one who can hear the IBOC who cannot equally well hear the AM. So, why do IBOC at all? - I must be missing something. What is it?

AM's still running I-Buzz: Could be because of their contracts with iBiquity. Certainly iBiquity would want to hold a grasp on AM stations for as long as they can with certain requirements. I'm sure that as soon as those contracts expire, we'll see a lot less AM's doing i-Buzz.

 

[reelyreal]

Move AM to channels 5&6, give them power outputs equivalent to their current coverage as best can be matched. WABC in NY can run 100kW, for example. Make the new band be able to support class C stations no matter the region.

Of course that will never happen because the FM stations now don't want AM to be on parity with them and compete for the same younger crowd and revenue.

Actually, the bigger stumbling block is the FCC's desire to repurpose some TV spectrum for wireless broadband. It's more likely that 5 & 6 will head that way.

 

[dumber than a box of hair]

Amazing, though, how those OFDM (stands for orthogonal frequency-division multiplexed) IBOC carriers can produce such loud hiss at 1% of the analog carrier power. Most likely, that phenomenon is at least in part a result of different methods for calculating the analog and digital power. Maybe somebody else can explain that. Bob Savage, are you lurking here?

I'm not Bob Savage, but I do play him on TV.

The primary HD carriers occupy the frequencies from +/-10356.1 to +/-14716.6 Hz removed from the analog carrier, placing them right on top of the adjacent channels. There are a total of 162 digital carriers throughout the HD spectrum of each channel, and carriers 57 through 81 occupy the primary carrier space previously described. The secondary (+/-5087.2 to +/-9447.7 Hz) and tertiary (+/-363.4 to +/-4723.8 Hz) carriers stay within the normal 10kHz channel passband, although they are much lower in level due to their being closer to the analog carrier and sidebands. Supposedly all of this meets the occupied bandwidth specs of 47 CFR §73.44 (according to iBiquity's specs), where emissions between 10.2 and 20 kHz removed from the analog carrier must be at least 25dB below the level of the unmodulated analog carrier. The huge "but" here is that the FCC's occupied bandwidth specs never envisioned stations intentionally placing carriers inside the passband of adjacent-channel stations, and unfortunately we can now hear the results of doing so.

 

[DanStrassberg]

The primary HD carriers occupy the frequencies from +/-10356.1 to +/-14716.6 Hz removed from the analog carrier, placing them right on top of the adjacent channels. There are a total of 162 digital carriers throughout the HD spectrum of each channel, and carriers 57 through 81 occupy the primary carrier space previously described. The secondary (+/-5087.2 to +/-9447.7 Hz) and tertiary (+/-363.4 to +/-4723.8 Hz) carriers stay within the normal 10kHz channel passband, although they are much lower in level due to their being closer to the analog carrier and sidebands. Supposedly all of this meets the occupied bandwidth specs of 47 CFR §73.44 (according to iBiquity's specs), where emissions between 10.2 and 20 kHz removed from the analog carrier must be at least 25dB below the level of the unmodulated analog carrier.

Great info, thanks! But is the 25 dB figured on a voltage basis or a power basis? If power, it would be a skosh more than 1/200th, right??? If voltage, it would be the square root of 1/200th, right??? That would be about 1/14th, right? But how you measure the voltage ratio or power ratio is important, right? The analog signal most definitely does not resemble white noise. The digital signal is not white noise either, but it sounds like it, and my guess is that if you viewed the carriers in the time domain (i.e. on an oscilloscope) and NOT in the frequency domain (on a spectrum analyzer) you might have quite a difficult time distinguishing the waveform from white noise. Enough playing with the scope's sweep speed and trigger mode and trigger parameters might actually produce a display that you could distinguish from noise, but setting up the scope could take some time. Anyhow, how do you determine the numerical value of the IBOC and analog signals? True RMS? Fudged average voltage? Something else?

 

[4CX1000A]

With all of the noise impacting AM stations these days, even the 50 kW blowtorches, I'm amazed any of you can discern IBOC noise from the rest of it. When power line and traffic light interference cause the local 50 kW station to completely disappear in my car on my drive home everyday, IBOC is the least of my concerns.

As someone who has done a lot of driving around listening to AM over the years, I can't say I perceive any increase in this sort of noise. Interference from distant (and sometimes not-so-distant) stations, on the other hand, has got very bad over the past two or three decades.

 

[WNTIRadio]

Actually, the bigger stumbling block is the FCC's desire to repurpose some TV spectrum for wireless broadband. It's more likely that 5 & 6 will head that way.

3

That's an issue for UHF spectrum. Don't see that happening with the lower VHF frequencies, as the receive antenna needs to be too big to stick in a smartphone or other device. And the digital propagation stinks there, that's why all the channel 6's in the country on DTV stink. Some moved back to their old UHF allotments. That's why Ch. 5 & 6 are perfect for adding additional FM frequencies. They're right next to the current FM band, and radios in Japan already go down to 76MHz. It would most likely be a simple thing as unlocking those frequencies in any radio. My Sony already tunes down that low.

 

[carmen]

and WMKI had instead spent their hundred thousand dollars to build gold plated statues of Fred Flintstone

actually they spent about $2 on halloween decorations. since AM IBOC is only noise-blasting conservative talk and C2C alien-chat anyways, its not a big problem imo.

 

[dumber than a box of hair]

The primary HD carriers occupy the frequencies from +/-10356.1 to +/-14716.6 Hz removed from the analog carrier, placing them right on top of the adjacent channels. There are a total of 162 digital carriers throughout the HD spectrum of each channel, and carriers 57 through 81 occupy the primary carrier space previously described. The secondary (+/-5087.2 to +/-9447.7 Hz) and tertiary (+/-363.4 to +/-4723.8 Hz) carriers stay within the normal 10kHz channel passband, although they are much lower in level due to their being closer to the analog carrier and sidebands. Supposedly all of this meets the occupied bandwidth specs of 47 CFR §73.44 (according to iBiquity's specs), where emissions between 10.2 and 20 kHz removed from the analog carrier must be at least 25dB below the level of the unmodulated analog carrier.

Great info, thanks! But is the 25 dB figured on a voltage basis or a power basis? If power, it would be a skosh more than 1/200th, right??? If voltage, it would be the square root of 1/200th, right??? That would be about 1/14th, right? But how you measure the voltage ratio or power ratio is important, right? The analog signal most definitely does not resemble white noise. The digital signal is not white noise either, but it sounds like it, and my guess is that if you viewed the carriers in the time domain (i.e. on an oscilloscope) and NOT in the frequency domain (on a spectrum analyzer) you might have quite a difficult time distinguishing the waveform from white noise. Enough playing with the scope's sweep speed and trigger mode and trigger parameters might actually produce a display that you could distinguish from noise, but setting up the scope could take some time. Anyhow, how do you determine the numerical value of the IBOC and analog signals? True RMS? Fudged average voltage? Something else?

I'd have to assume it's voltage, since you're supposed to use a sweep-frequency RF spectrum analyzer and ideally get your sample directly from the transmitter output while operating into a non-reactive dummy load.

 

[aaronread]

For FM, it's power-based. I don't know for sure about AM, but I always assumed it was the same for both.

FWIW, I have to wonder if WBZ transmitted in analog only but used its full 10kHz bandwidth instead of narrowing to 5kHz (like a significant majority of AM stations do), would you see similar interference to KDKA in Binghamton as you did due to the HD carriers?

Also FWIW, I don't think KDKA really cares too much about interference to their nighttime signal 250 miles away from Pittsburgh (where Binghamton is). However, I'll give a nod to Bob Savage who I personally think has made a credible case that his station, WYSL 1040, *is* receiving *some* IBOC interference from WBZ...even during the day...in his city of license in Avon/Rocheser. Whether that interference is really enough to make a credible argument for lost audience is another story. The entire AM band, even when you've got top-notch operators like Bob, is in serious trouble these days. There's a reason why so many AM stations, including WYSL, have worked so hard to acquire FM translators or even full-power stations to migrate to.

 

[mgpt6]

Can part of the problem AM faces today be laid at the feet of the makers of AM radios today in both car and home. Which was better, the IC AM radio of today or the 5 tube AM Radio of the 50s and 60s?

 

[DG02816]

The All-American 5 had better bandwidth, and decent sensitivity.