[opendtv] Re: Broadband DTV interferers
- From: "Dale Kelly" <dalekelly@xxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sat, 26 Jan 2008 10:46:43 -0800
Bert wrote:
> Try that with large-area SFNs creating supposed cookie-cutter patters,
> where frequency is reused between markets. Recurring interference
> problems are practically inevitable.
Yep.
Tests of SFN implementations using the ATSC RP are/were running and to my
knowledge have not yet achieved satisfactory performance. This SFN
performance issue is not isolated to ATSC.
Dale
> -----Original Message-----
> From: opendtv-bounce@xxxxxxxxxxxxx
> [mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Manfredi, Albert E
> Sent: Friday, January 25, 2008 1:57 PM
> To: opendtv@xxxxxxxxxxxxx
> Subject: [opendtv] Re: Broadband DTV interferers
>
>
> Craig Birkmaier wrote:
>
> > Do you think Bert would be willing to pay to help build
> > the infrastructure for a service that could deliver 40 or more
> > different programs to him in the free and clear?
>
> Yes, I would, because it would be a one-time expense. I object to being
> suckered into every Tom, Dick, and Harry's scheme of creating yet
> another "infinite revenue stream" for themselves. Certain things one
> should only have to pay for at the time of purchase.
>
> (I may not have a rigorous way of defining what these things are, but
> radio and TV are in that list.)
>
> But your reponse to Dale is exactly why I wrote my response to Dale.
> It's not at all the one-time cost of changing the infrastructure that's
> the issue here. It is that your recurring ideas are deeply flawed. If
> the infrastructure has to be changed, it had better be for a better one,
> not for one that results in recurring problems and high operating and
> maintenance costs.
>
> SFNs are tricky, as soon as you place towers further apart than the echo
> tolerance allows. It's such a simple stipulation that I don't understand
> how you keep forgetting that.
>
> Want a real-world example?
>
> You can use all the fancy models you want, like Longley-Rice, to help
> locate your towers. But signals from towers that are way too far apart
> *will* in fact interfere, at least some of the time.
>
> Proof? Easy. According to Antennaweb, which uses Longley-Rice, I should
> barely be able to receive our local DTT stations, let along Baltimore.
> Yet, I receive some Baltimore stations with greater margin than some
> local ones.
>
> Try that with large-area SFNs creating supposed cookie-cutter patters,
> where frequency is reused between markets. Recurring interference
> problems are practically inevitable.
>
> Remember: cell phone networks ARE NOT SFNs.
>
> Bert
>
>
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