HD AM vs DRM

[Ai4i]

What is the difference?
I think DRM is strictly digital, while HD AM is hybrid.
Will the HD AM stations ever phase out the analogue component as the FM stations plan to do, and if/when they do, will they have room for two independent audio programs?
FM stations are alloted 96Kb of digital bandwidth to slice up. How much digital bandwidth do the AM stations have?<P ID="signature">______________
Proud 2 B a pioneering satellite radio subs¢riber
Ai4i is always on the trailing edge of technology
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[vtjazy]

> What is the difference?
> I think DRM is strictly digital, while HD AM is hybrid.
> Will the HD AM stations ever phase out the analogue
> component as the FM stations plan to do, and if/when they
> do, will they have room for two independent audio programs?
> FM stations are alloted 96Kb of digital bandwidth to slice
> up. How much digital bandwidth do the AM stations have?
>


From what I recall (somebody correct me if I'm wrong), DRM usually runs on frequencies in the gigahertz range. The concept behind HD (IBOC) is that it shares the same spectrum as the analog broadcast; DRM uses different spectrum, and usually has more bandwidth.

IBOC on AM, if I remember corectly, is 32 kbps worth of bandwidth. It might be 48, but I don't think it's any higher than that. It's been a while since I last read the spec.

 

[Ai4i]

>
> From what I recall (somebody correct me if I'm wrong)
>

No, <a target="_blank" href=http://www.drm.org/system/technicalaspect.php>DRM</a> uses the same frequencies 153KHz-26.1MHz as standard longwave, mediumwave, and shortwave stations.<P ID="signature">______________
Proud 2 B a pioneering satellite radio subs¢riber
Ai4i is always on the trailing edge of technology
_______________</P>

 

[sbe]

AM IBOC or HD will not work at nite and it not authorized for nite ops. Unless they find a way to stop the tremendous interference AM HD causes it's neighbors on the band, it may not fly at all.
Dont hold your breath on analog radio going away.. There are over 800 million radio receivers in the US, that will be junk if analog goes away. Also, the FCC did not mandate a drop dead date for analog like they did for TV.

Try listening to KDKA anywhere a few miles east of Pittsburgh after 4 or so in the afternoon. That very annoying hiss is coming from WBZ in Boston. See how bad the intererence is??? AM IBOC is not ready for prime time. Also on FM a lot of the rimshots that like to call themselves a station of the big nearby city will have their extended coverage go away when their neihbors fire up the IBOC. Although not quite as destructive as AM it will still cause problems to the rimshots.




> >
> > From what I recall (somebody correct me if I'm wrong)
> >
>
> No, DRM uses the same frequencies 153KHz-26.1MHz as standard
> longwave, mediumwave, and shortwave stations.
>

 

[Mediafrog]

> No, DRM uses the same frequencies 153KHz-26.1MHz as standard
> longwave, mediumwave, and shortwave stations.

Increasing number of DRM broadcasts on shortwave, many audible here in North America. The CBC shortwave facility at Sackville, New Brunswick has a number of transmissions from various broadcasters, and the Radio Netherlands Bonaire transmitting plant has a DRM capable transmitter as well. Deutsche Telekom's T-Systems in Germany is also doing some DRM broadcasts, just to name a few.

For a full picture about DRM, go to http://www.drm.org/

 

[Mediafrog]

> There are over 800 million radio receivers in the US, that will be
> junk if analog goes away.

Analog radio won't go away any time soon, but it won't be around forever, either. It will eventually be replaced with some sort of digital format, whether on the current AM or FM bands, or elsewhere in the radio spectrum. The big question is whether future generations of wireless internet based distribution will make AM/FM irrelevent to the point that it fades away, or do broadcasters devise some sort of migration scheme to full digital on the existing bands?

I can see the current 88-108 MHz FM band going full digital. The future of the current AM band is very murky at best due to the skywave issues at night, plus other propagation considerations. It wouldn't surprise me to see AM eventually shut down completely and the frequencies reallocated for other non-broadcast use.

> Also, the FCC did not mandate a
> drop dead date for analog like they did for TV.

Eventually they'll have to. Many years, really decades away. I doubt we see any serious movement on this for at least 20-25 years.

 

[wkbam1690]

> It wouldn't surprise me to see AM
> eventually shut down completely and the frequencies
> reallocated for other non-broadcast use.
>
Wouldn't nighttime skywave discourage non-broadcast use? Also the size of efficient antennas at these frequencies could be cost-prohibitive.

 

[Ai4i]

> It wouldn't surprise me to see AM
> eventually shut down completely and the frequencies
> reallocated for other non-broadcast use.
>

Amen, should have happened a loooong time ago.
Lots of FM stations are or will be carrying their weak signal AM's on their HD-3 and HD-4 channels. The FCC can require FM's to carry stand alone AM's on their extra HD streams (at a reasonable cost) or buy them out, just as a station can not legally maintain exclusive rights to a premium antenna site.<P ID="signature">______________
Proud 2 B a pioneering satellite radio subs¢riber
Ai4i is always on the trailing edge of technology
_______________</P>

 

[k9ez]

> > It wouldn't surprise me to see AM
> > eventually shut down completely and the frequencies
> > reallocated for other non-broadcast use.
> >
>
> Amen, should have happened a loooong time ago.
> Lots of FM stations are or will be carrying their weak
> signal AM's on their HD-3 and HD-4 channels. The FCC can
> require FM's to carry stand alone AM's on their extra HD
> streams (at a reasonable cost) or buy them out, just as a
> station can not legally maintain exclusive rights to a
> premium antenna site.
>


A station cannot maintain exclusive rights to a premium antenna site???? I see it all of the time.

 

[Ai4i]

> A station cannot maintain exclusive rights to a premium
> antenna site???? I see it all of the time.
>

I remember reading as a child back in the 50s or 60s that somewhere in the books there are words written to the effect that if, for example, you own a mountain top, the highest point in the area with none similar, you must lease space or somehow give your competition an option to use that space.
I do not know what the actual enforcement policy has been like.<P ID="signature">______________
Proud 2 B a pioneering satellite radio subs¢riber
Ai4i is always on the trailing edge of technology
_______________</P>

 

[_Jim]

Other uses - for AM broadcast spectrum?

> It wouldn't surprise me to see AM eventually shut
> down completely and the frequencies reallocated for
> other non-broadcast use.

Like what, may I ask?

What 'modes' or services could use that spectrum?

Antennas (for transmitting) in that range are outrageous
in size, have -narrow- bandwidths, and the signals
don't propagate well into buildings (from powerful
broadcast sites let alone from some 'wimpy' 100 W
trasmitter using a short, compromise antenna that
could be located across town).

On another note, what other broadcasting mode is able
to provide reliable 150 mile coverage, besides AM
broadcast frequencies?

Not FM broadcast.

FM broadcast, being in the VHF spectrum is decidely is
line-of-sight, whereas AM in the MW spectrum provides
groundwave coverage quite aways beyond line-of-sight
owing to continuous 'diffraction' (bending) over the
surface of the earth.