A Modest Proposal

[K6JHU]

With apologies to Jomathan Swift.

There is a continuing thread on this board about KBRT virtually eliminating one of their HD sidebands. So suppose that we have an agreement that even numbered stations (640, 660, 680) use only the upper sideband and the odd numbered stations (650, 670, 690) use only the lower sidebands. That way all the IBOC noise would be in the same place

 

[IT_Guru]

With apologies to Jomathan Swift.

There is a continuing thread on this board about KBRT virtually eliminating one of their HD sidebands. So suppose that we have an agreement that even numbered stations (640, 660, 680) use only the upper sideband and the odd numbered stations (650, 670, 690) use only the lower sidebands. That way all the IBOC noise would be in the same place

I would like this agreement if the elimination of the sidebands were reversed. I live 50 mi. west of KDKA 1020 in Pittsburgh but can't receive them at night because of WBZ 1030 from Boston.

 

[Savage]

And there you have it, K6 - your solution at first glance appears logical, until you realize that the victim stations' frequencies - those being interfered with - do not necessarily correspond with the staggering model you posit.

The best solution is to eliminate both IBOC sidebands. As in: turn off the hash generators entirely. Nobody's listening, nobody cares and the system barely works in the real world anyway.

All this for a screechy 16 kbps? Usually in mono? No secondary channels? Give me a break.

 

[briankay]

Having only one IBOC sideband would also mean the digital signal would drop while passing under every bridge, which typically doesn't happen with 2 side bands because of the 5 second audio time diffence between the lower and upper sidebands (unless it takes longer than 5 seconds to pass under the bridge, such as when moving slowly). It continuously monitors and switches to the optimum side band.
To correct a previous post the core digital signal is 20 kbps and the lower power enchanced signal adds another 18 kbps (total 38 kbps). From my experience, the sound quality is very good even when it's just 20 kbps mono. I guess it depend on the source audio and the processing the station is feeding it. I also get good HD AM reception up to 120 miles from 50 kW transmitters especially on the lower frequencies, not bad when you consider that an AM in all digital mode (if/when that ever happens) would be 15 dB more powerful (32X power) and the adjacent interference issues would be for all intents and purposes gone. This is where I would like AM to be, hopefully some would agree)

 

[Play Freebird]

I also get good HD AM reception up to 120 miles from 50 kW transmitters especially on the lower frequencies, not bad when you consider that an AM in all digital mode (if/when that ever happens) would be 15 dB more powerful (32X power) and the adjacent interference issues would be for all intents and purposes gone. This is where I would like AM to be, hopefully some would agree)

The "some" who would probably agree are owners of 50 kW Class A stations especially on the lower frequencies -- but where does this leave the rest of us who have Class Bs with tight patterns, Class Cs on "graveyard channels" and Class Ds with no nighttime authorization? Seriously, what does HD offer to the less fortunate, other than an increase in received interference and a hole into which we can throw away money?

If you're really open-minded about digital radio, let the FCC know that you support the use of TV channels 5 and 6 as a digital transition band for AM licensees. What could we offer the Federal government in return for this spectrum? How about a dedicated subcarrier to send enhanced public emergency text messages without the need to interrupt regular programming, as is presently the case with EAS? Would IPAWS offer the opportunity for Congress and the FCC to act on this proposal?

http://www.radio-info.com/sections/...ting-fm-radio-chips-into-phones-other-devices

 

[SUPERCASTER]

Having only one IBOC sideband would also mean the digital signal would drop while passing under every bridge, which typically doesn't happen with 2 side bands because of the 5 second audio time diffence between the lower and upper sidebands (unless it takes longer than 5 seconds to pass under the bridge, such as when moving slowly). It continuously monitors and switches to the optimum side band. To correct a previous post the core digital signal is 20 kbps and the lower power enchanced signal adds another 18 kbps (total 38 kbps). From my experience, the sound quality is very good even when it's just 20 kbps mono. I guess it depend on the source audio and the processing the station is feeding it. I also get good HD AM reception up to 120 miles from 50 kW transmitters especially on the lower frequencies, not bad when you consider that an AM in all digital mode (if/when that ever happens) would be 15 dB more powerful (32X power) and the adjacent interference issues would be for all intents and purposes gone. This is where I would like AM to be, hopefully some would agree)

"the 5 second audio time diffence between the lower and upper sidebands (unless it takes longer than 5 seconds to pass under the bridge, such as when moving slowly). It continuously monitors and switches to the optimum side band. "
Huh?

"AM in all digital mode (if/when that ever happens) would be 15 dB more powerful (32X power) and the adjacent interference issues would be for all intents and purposes gone. "
What happens to the co-channel stations?
Obliteration?

Credible sources PLEASE!

 

[Seattleradiodude]

What the HD Bashers on this board never seem to understand is that the HD CODEC sounds much better than .MP3
They try to mislead people by using "Low Bitrates" as an excuse for poor audio, however anyone who has heard the difference between a 32kbps .MP3 and a 32kbps AAC+ should know that different Codec’s provide higher quality at lower bitrates, and that is the case for the HD codec as well.

Its all about the programming source and Proper processing in the way HD is perceived. A hard driven, high modulation, traditional processing algorithm doesn’t work on the Digital Stream. Which is why a processor with parallel processing is required. Keep the high compression on the Analog and Dynamic range in the Digital.

 

[audioguy]

A 32 kbps AAC may sound better than a 32 kbps MP3, but it is still far from anything that could even remotely be considered "high fidelity" (to use a term from an earlier time), let alone "High Definition". Give me a break!

I would like to offer a different modest proposal. I have read that it is technically feasible to synchronize all of the AM carriers using GPS. Is this true? What equipment is needed? What would it cost?

It would be a very interesting experiment to try this on one of the channels that has relatively few stations on the air at night and see how much of an improvement it would make. What do you gents think?

 

[radioskeptic]

Quote from Seattleradiodude:

What the HD Bashers on this board never seem to understand is that the HD CODEC sounds much better than .MP3
They try to mislead people by using "Low Bitrates" as an excuse for poor audio, however anyone who has heard the difference between a 32kbps .MP3 and a 32kbps AAC+ should know that different Codec’s provide higher quality at lower bitrates, and that is the case for the HD codec as well.

But Dude, "HD" doesn't use AAC+ -- it uses Iniquity's own proprietary codec, which isn't nearly as good as AAC+.

FMeXtra, however does use the superior, open source AAC+ codec because DRE/VuCast, unlike Iniquity, isn't trying to squeeze extra royalty licensing profits out of their system with a proprietary codec, the algorithms for which are supposed to be a trade secret.

And really, what's not to bash? Approving Iniquity's junk technology is the biggest mistake the FCC has made since they temporarily authorized the Rube Goldbergesque, semi-mechanical CBS color TV system back in the early Fifties!

 

[Play Freebird]

I would like to offer a different modest proposal. I have read that it is technically feasible to synchronize all of the AM carriers using GPS. Is this true? What equipment is needed? What would it cost?

It would be a very interesting experiment to try this on one of the channels that has relatively few stations on the air at night and see how much of an improvement it would make. What do you gents think?

Some AM transmitters (the current Nautels, for instance) have the ability to lock carrier to an external 10 Mhz reference, so all these would need is a GPS or rubidium frequency standard, both of which are available cheap on the surplus market -- or even for free. In my shop, I have a nice Trimble "Thunderbolt" GPS clock that came out of an E911 box that a PCS company abandoned when it left our tower site. I use it as a reference for my spectrum analyzer and to calibrate the portable frequency counter. TAPR offered these a couple of years ago but unfortunately they're sold out:

http://www.leapsecond.com/pages/tapr-tbolt/

Many other transmitters manufactured since AM stereo was approved have a connector for an external oscillator, so in this case you would simply add an outboard synthesized oscillator that can lock to the 10 MHz reference. Spectracom in Rochester, NY is one of several sources:

Even if purchased new, all the necessary stuff can be found for less than $1000:

http://www.tenmhz.com/products.htm

 

[Play Freebird]

Its all about the programming source and Proper processing in the way HD is perceived. A hard driven, high modulation, traditional processing algorithm doesn’t work on the Digital Stream. Which is why a processor with parallel processing is required. Keep the high compression on the Analog and Dynamic range in the Digital.

Nice idea in theory, but if the compression characteristics aren't similar on both sides, then "blending" becomes distracting.

And regardless of the codec, 32 k just isn't going to provide high fidelity. Think about it; the minimum Nyquist sampling frequency for 15 kHz audio bandwidth would be 30 kHz, assuming "brickwall" lowpass filters - however, that's not realistic so we typically sample at a minimum of 32 k.

So... if the bitrate of a lossy codec is the same as the sample frequency, only 1 bit is allowed on average to define each sample, rather than the 16 bit resolution used in linear (compact disk) recordings. That's too much crunch for our ears to ignore.

 

[KB1OKL]

When I was experimenting with my waste of money IBOC tuner WBZ sounded like krap in IBOC when I could actually get it in with my Crane twin coil ferrite bar antenna 40 miles from the transmitter, it sounded strident, sibilant and overly bright, sounded kind of like a cheap three way speaker with an open midrange speaker. I couldn't listen to something that sounded like that for more than a minute.