[opendtv] Re: Twang's Tuesday Tribune (Mark's Monday Memo)2004April20
- From: "Manfredi, Albert E" <albert.e.manfredi@xxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Wed, 21 Apr 2004 18:00:23 -0400
> Victor Tawil of the Association for Maximum Service Television (MSTV)
> presented a paper today on tests MSTV conducted in the
> Washington, D.C.
> area using the Zenith 5th-generation chip. The tests were
> conducted in
> a portion of Virginia, right across the river from
> Washington, that has
> tall buildings. The sites were selected because they were considered
> tough, so the percentages of success don't reflect percentages of the
> overall population. All of the tests were conducted outdoors.
That's very interesting, because the site you're talking about
must be the Rosslyn office district, exactly where Linx conducted
their tests one year ago (the ones specifically in Rosslyn achieved
82.3 percent success, 5' antenna height, no reaiming allowed after
the first success). See
http://www.linxelectronics.com/pdf/04-08%20LINX%20NAB%20MSTV%20-%20MSTV.p=
df
> In 14 of the 78 tests, the signals were considered below=20
> threshold. I=20
> don't know whether that means below 15.5 dB C/N or below=20
> threshold for=20
> the necessary equalization (the 5th-generation Zenith=20
> requires 24 dB C/N=20
> for the Brazil-E ensemble). In any case, those 14 were=20
> deleted and did=20
> not count against the percentages. Of the rest, there was a=20
> 65% success=20
> rate (fewer than four hits in three minutes); measured the old way=20
> (fewer than 50 hits in three minutes) there would have been an 86%=20
> acceptable rate.
>=20
> That's the fifth-generation, not the first.
Sounds like 5th gen Zenith < 4th gen Linx? Although you say
"indoors" and not just at low altitude, but outdoors. Possibly,
a much harder reception environment.
The Linx test used all Washington and one Annapolis station, 13
sites, 78 measurements. No Baltimore stations used for the
Washington area test. Perhaps that's cheating, but then again,
this was using only a dipole at 5' altitude.
> Those of us who=20
> participated in the old Sinclair trials would be hard pressed=20
> to come up=20
> with one site that failed.
You went indoors, in reinforced concrete and steel buildings,
and had as many transmitters to try to receive?
> The 5th generation is certainly better than the 4th, and Zenith is=20
> working on a 6th.
5th gen for Zenith might be better than 4th gen for Zenith, but
there need be no correlation among generations from different
companies.
Bert
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