[opendtv] Re: TV Technology: ATSC 3.0 Prototypes Expected in 2016
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: "opendtv@xxxxxxxxxxxxx" <opendtv@xxxxxxxxxxxxx>
- Date: Fri, 20 Feb 2015 00:29:41 +0000
Craig Birkmaier wrote:
>> Did you read the document that explains this? What is the correlation
>> between b/s/Hz and tower spacing with LTE broadcast, Craig?
> I have read several documents that discuss this. Thus one is quite
> interesting; I think we have referenced it before.
http://www.ericsson.com/res/thecompany/docs/journal_conference_papers/wireless_access/p22-huschke.pdf
> There are many trade offs, but inter site distance can vary from 2
> to 10 Km depending on population density,
Not on population density, but on spectral efficiency. Pay attention starting
on page 27. Pay attention to the numbers, and then think about the fact that
broadcasters are losing 1/3 of the spectrum they've been left with after 2009.
What is the spectral efficiency at 10 km spacing (6.2 miles)? What is the
spectral efficiency at 2 km (1.2 miles)? How much bandwidth are they getting
out of each channel, compared with ATSC? **And**, do their numbers hold for 30'
receive antenna height, or do they hold for handheld service?
Now, step 2, assuming even the much-lower-than-ATSC spectral efficiency at the
6.2 mile spacing (which they assume for rural settings, where spectrum is more
plentiful and therefore spectral efficiency less important), how many towers
*and transmitters* are needed to cover, say, a market of 40 mile radius? With
the 1.2 mile spacing? Do the simple arithmetic, Craig, for once. Now, is this
something affordable for a FOTA TV business model?
> The example cited is 84 MHz of spectrum to replicate what takes
> 300 MHz with high power, high tower systems.
Mostly BS. I've already explained this years ago. The figure 84 MHz compares
with 72 MHz or less for ATSC, **not** 300 MHz. 300 MHz is the total spectrum
available nationwide, to prevent co-channel interference. Whereas 84 MHz is
only the spectrum they need for *one* market. It does not take into
consideration any of the troublesome details, such as adjacent markets that
require overlap, or small local stations close to major markets. At the very
least, to compare apples with apples, you would need more than twice that 84
MHz. In some locations, you need three times that 84 MHz.
And, ATSC is set to lose 100 MHz. So what we really have is perhaps 250 MHz
total required for LTE broadcast, compared with 200 MHz we have to live with,
which can better be accomplished with ATSC or DVB-T2.
Or, re-read this quote, Craig:
"In our example of one HDTV and on SDTV station being transmitted via one ATSC
channel, only 13 Mb/s are transmitted via a ATSC channel that is capable to
transport up to 19.2 Mb/s. Consequently, 37% of the spectrum saving (i.e.
1-13Mb/s / 19.2Mb/s) is due to multiplexing TV programs, so that no unused
capacity remains in the MBMS system."
Can you really not ferret out BS when you read it? Do you really think that
ATSC is limited to transmitting one HD and one SD program per channel, taking
up a supposed 13 Mb/s of capacity, and that the rest of the 19.3 Mb/s capacity
MUST be wasted for sake of multiplexing? Or do you think they use a wasteful
example on purpose, to fool the innocent (such as they obviously have done)
into thinking this must be the general case with ATSC?
> The Ericsson paper chose not to compare total power usage for a
> market due to lack of information at the time the paper was written.
Is power usage the most important cost item, or does labor matter more?
> I expect many broadcasters may sell their spectrum and continue
> operations via direct feeds to MVPD services and the Internet,
How will broadcasters "add value" for content distributed over the Internet,
when the networks can provide this directly? I already covered that, Craig.
Bert
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