[opendtv] Re: STATEWIDE DTV TEST
- From: "Dale Kelly" <dalekelly@xxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Sat, 20 Dec 2008 11:29:48 -0800
> I'd worry too. Especially because WPVI analog, on Ch 6, is
> transmitting an ERP of 74.1 KW, whereas in digital, they are
> scheduled for 7.56 KW, on the same tower. That's a 9.9 dB
> reduction in power.
Equivalent power for analog to DTV is not 1:1.
The analog picture power level is about 6db lower than it's peak power
level, where the extra 6db is used to transmit the synchronizing pulses.
Since those sync pulses are not part of the DTV signal, an equivalent DTV
power level for your example would be about 18.5KW. In this case the channel
6 DTV power is still down 3 to 4 db below equivalency, which is certainly
problematic.
> -----Original Message-----
> From: opendtv-bounce@xxxxxxxxxxxxx
> [mailto:opendtv-bounce@xxxxxxxxxxxxx]On Behalf Of Albert Manfredi
> Sent: Thursday, December 18, 2008 10:00 PM
> To: opendtv@xxxxxxxxxxxxx
> Subject: [opendtv] Re: STATEWIDE DTV TEST
>
>
>
> Cliff Benham wrote:
>
> > Ch 6 in Philly just did a two minute test with a
> > 'fail' message on the analog channel to allow
> > people to check all their TVs.
> >
> > The problem with CH A6 is that they will ultimately
> > return from D64 to D6 at the end of the transition
> > in ??several years. Right now I can only get a very
> > bad analog CH6 with a deep fringe antenna 37 miles
> > from their tower. I wonder if I'll get /anything/
> > when they return to Ch 6 as digital?
>
> I didn't think you had a VHF antenna, though?
>
> I'd worry too. Especially because WPVI analog, on Ch 6, is
> transmitting an ERP of 74.1 KW, whereas in digital, they are
> scheduled for 7.56 KW, on the same tower. That's a 9.9 dB
> reduction in power. If analog reception is very bad now, it seems
> dicey for digital with such a power drop.
>
> That's also my concern here, with the two local and two Balt
> channels going back to VHF. I'm certainly not counting on getting
> the Balt channels any longer. The power drop in these markets,
> compared with their analog VHF, is even bigger than you have to
> deal with there.
>
> Bert
>
> _________________________________________________________________
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cq_broad2_122008
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