[opendtv] Re: The "real" problem with OFDM in the U.S.

Manfredi, Albert E wrote:
 > If you want to avoid dead zones, as we must here,
 > then adjacent markets won't be able to share
 > frequencies. Even with the small stick approach.
 > But the next market over can use those frequencies,
 > *same as now*.

Is there any topography where someone located equally (at any distance) 
between two stations with the same power and channel is not in a dead zone?

- Tom


> Craig Birkmaier wrote:
> 
> 
>>The coverage criteria was based on the same old
>>story - market-into-market interference. It had
>>almost nothing to do with equaling NTSC coverage,
>>other than the reality that you still have to
>>protect for interference into neighboring markets.
> 
> 
> Correct. Which means, it had a lot to do with
> coverage, and the constraints are the usual ones:
> preventing interference between adjacent markets.
> 
> As always, context matters. So let's ask "as opposed
> to what?"
> 
> If there are no clearly defined "guard zones" between
> markets, where no signal is required, then this
> interference issue will *always* emerge. Even with
> small sticks in SFNs.
> 
> There are no dead zones between markets up and down
> the East Coast, for example. Less sparsely populated
> areas, sure. But they all belong to at least one
> market, if not two markets.
> 
> It would be possible to create coverage, with some
> amount of realism, with smaller, lower power sticks,
> spread reasonably far apart. This requires
> synchronization between towers (that no COFDM
> country has adopted as a solution yet). But okay,
> let's postulate such a scheme. It can be done here
> as well as anywhere.
> 
> If you want to avoid dead zones, as we must here,
> then adjacent markets won't be able to share
> frequencies. Even with the small stick approach.
> But the next market over can use those frequencies,
> *same as now*.
> 
> An example might be Balt/Wash, Philadelphia, NYC.
> Baltimore and Washington overlap, and must do so.
> Many communities belong to both markets.
> 
> The area between the Balt/Wash and Phila markets
> must also be covered completely. No justification
> for creating dead zones. Whether you deploy big
> or small sticks, this means that you can't use
> the same frequencies in Balt/Wash and Philadelphia.
> And many of those communities would belong to
> both Baltimore and Phildelphia markets anyway,
> legitimately, which further makes the point.
> 
> So the question is, can the next major market over,
> NYC, use the same frequencies as Balt/Wash?
> 
> NYC and Baltimore (and DC) use the same VHF
> frequencies (Channels 2, 4, 5, 7, 11). VHF being
> worst case, this shows that if you want to
> create continuous coverage, big sticks and
> smaller sticks don't make a huge difference in
> terms of frequency planning.
> 
> It's coverage area without dead zones that creates
> the problem. We have big markets to cover here,
> and no wilderness areas between them.
> 
> I'll agree that a more sharply defined coverage
> contour can reduce interference further away from
> the boundary zones between adjacent markets, But
> where it really *matters*, there is not a big
> difference. And the frequency plans would not
> be dramatically different. And *certainly* not if
> you stick to your idea of three or four towers
> only, per major market. That design wouldn't even
> create a particularly sharp contour.
> 
> Bert
>  
>  
> ----------------------------------------------------------------------
> You can UNSUBSCRIBE from the OpenDTV list in two ways:
> 
> - Using the UNSUBSCRIBE command in your user configuration settings at 
> FreeLists.org 
> 
> - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word 
> unsubscribe in the subject line.
> 
> 
 
 
----------------------------------------------------------------------
You can UNSUBSCRIBE from the OpenDTV list in two ways:

- Using the UNSUBSCRIBE command in your user configuration settings at 
FreeLists.org 

- By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word 
unsubscribe in the subject line.

Other related posts: