hwh wrote:
On 9/12/10 7:51 PM, dave wrote:
Richard Evans wrote:

As for digital radio, unless they launch using something that is
actually better than FM, then we are better off sticking with FM. What
is frustrating, is that they could quite easily come up with a system
that would wipe the floor with FM, but for one reason or another it just
hasn't been done.

Richard E.

A system like Sirius or XM can get 60 good sounding stereo channels in
4.5 MHz of spectrum

So obviously either they use more channels or they have less bandwidth
than that, because these sat systems are not good sounding ones.

I was wondering about this.

Could 60 channels in 4.5 Mhz of spectrum produce good sound quality?
Not sure, but thinking about it, it sounds unlikely.

Do they actually do this (providing 60 good sounding channels)?
I seriously doubt it.

Richard E.

On 9/12/10 8:43 PM, Richard Evans wrote:
So obviously either they use more channels or they have less bandwidth
than that, because these sat systems are not good sounding ones.

I was wondering about this.

Could 60 channels in 4.5 Mhz of spectrum produce good sound quality?
Not sure, but thinking about it, it sounds unlikely.

Do they actually do this (providing 60 good sounding channels)?
I seriously doubt it.

They don't. Far from it. 4,5 MHz of spectrum is quite a lot by the way,
but the signal strength from the satellite is not going to be strong.
For high efficiency or bits per Hertz you need a strong signal. ISTR the
average for the channels is 46 kbps.

gr, hwh

On Sep 12, 11:43*am, Richard Evans
wrote:
hwh wrote:
On 9/12/10 7:51 PM, dave wrote:
Richard Evans wrote:

As for digital radio, unless they launch using something that is
actually better than FM, then we are better off sticking with FM. What
is frustrating, is that they could quite easily come up with a system
that would wipe the floor with FM, but for one reason or another it just
hasn't been done.

Richard E.

A system like Sirius or XM can get 60 good sounding stereo channels in
4.5 MHz of spectrum

So obviously either they use more channels or they have less bandwidth
than that, because these sat systems are not good sounding ones.

I was wondering about this.

Could 60 channels in 4.5 Mhz of spectrum produce good sound quality?
Not sure, but thinking about it, it sounds unlikely.

Do they actually do this (providing 60 good sounding channels)?
I seriously doubt it.

Richard E.

Doing-the-Math : 4,500 kHz / 60 = 270 kHz per Channel
* Presently AM/MW is 10 kHz per Channel
* Presently FM is 200 kHz per Channel

? So Why Won't 270 kHz per Channel Work
for Digital Radio Broadcasting Formats ?

~ RHF

RHF wrote:


Doing-the-Math : 4,500 kHz / 60 = 270 kHz per Channel
* Presently AM/MW is 10 kHz per Channel
* Presently FM is 200 kHz per Channel

? So Why Won't 270 kHz per Channel Work
for Digital Radio Broadcasting Formats ?

I think hwh has fond the answer to that one. The signal from the
satellite is too weak.

Actually, for terrestrial broadcasting, with a reasonable signal level,
they ought to be able to do a lot better than that. But then they still
use outdated inefficient technology :-(

On 9/12/10 9:27 PM, Richard Evans wrote:
RHF wrote:


Doing-the-Math : 4,500 kHz / 60 = 270 kHz per Channel
* Presently AM/MW is 10 kHz per Channel
* Presently FM is 200 kHz per Channel

? So Why Won't 270 kHz per Channel Work
for Digital Radio Broadcasting Formats ?

I think hwh has fond the answer to that one. The signal from the
satellite is too weak.

Actually, for terrestrial broadcasting, with a reasonable signal level,
they ought to be able to do a lot better than that. But then they still
use outdated inefficient technology :-(

Take a look at the DVB-T2 specifications. That's what I call efficient.
How different from DAB or IBOC.

gr, hwh

RHF wrote:


Doing-the-Math : 4,500 kHz / 60 = 270 kHz per Channel
* Presently AM/MW is 10 kHz per Channel
* Presently FM is 200 kHz per Channel

? So Why Won't 270 kHz per Channel Work
for Digital Radio Broadcasting Formats ?

~ RHF
.

Error correction overhead. I think they are 1:2. So halve that spectrum.

Richard Evans wrote:


I was wondering about this.

Could 60 channels in 4.5 Mhz of spectrum produce good sound quality?
Not sure, but thinking about it, it sounds unlikely.

Do they actually do this (providing 60 good sounding channels)?
I seriously doubt it.

Richard E.

They cram 180 radio stations plus cartoons in that 4.5 MHz. They sounded
killer when they debuted 10 years ago with around 60 music channels
each. Just kept getting worse.