[opendtv] Re: Charles Rhodes on unlicensed devices and white spaces
- From: "johnwillkie" <johnwillkie@xxxxxxxxxxxxx>
- To: <opendtv@xxxxxxxxxxxxx>
- Date: Wed, 8 Aug 2007 11:10:59 -0700
It would depend on the impairment, no?
However, for most impairments, which are transitory and usually involve a
portion of a channel, a multicarrier system would seem to minimize
interference compared to a 'monolithic' carrier system.
(There are more than a few published studies on this topic.)
John Willkie
-----Mensaje original-----
De: opendtv-bounce@xxxxxxxxxxxxx [mailto:opendtv-bounce@xxxxxxxxxxxxx] En
nombre de Craig Birkmaier
Enviado el: Wednesday, August 08, 2007 6:35 AM
Para: opendtv@xxxxxxxxxxxxx
Asunto: [opendtv] Re: Charles Rhodes on unlicensed devices and white spaces
At 5:20 PM -0400 8/7/07, Manfredi, Albert E wrote:
>http://www.tvtechnology.com/pages/s.0072/t.7434.html
>
>Needless to say, he's against them. He favors repacking the DTT spectrum
>to accommodate these devices in a band of their own. He also doesn't
>have anything good to say about the possibility that these devices can
>adequately detect an open channel.
>
>My thought on this was, if a consumer-grade device is good enough to
>detect a very weak signal, which has to be well below -85 dBm, why
>wouldn't TV tuner manufacturers use such a tuner to improve TV
>reception?
There are many questions raised here. Once again the tuner front end
seems to be the area where things get messy.
A generic question here. Is a multi-carrier modulation system
susceptible to the same interference issues, or does the use of
multiple carriers help to mitigate the interference issues?
>
>One interesting stat he gives is that OTA signal strengths under -68 dBm
>(what the FCC calls weak) occur in 84 percent of DTT coverage area.
>(Note by area, not population.)
Why should this be any different than it has been for NTSC?
Obviiously the big sticks can't cover everything. This is the primary
reason that there are thousands of TV translators around the country,
trying to extend coverage to remote areas.
At some point one must ask what is the proper "mesh" of services to
deliver digital entertainment services to everyone? Clearly
terrestrial RF cannot reach everyone, although it may be feasible to
reach 95% or more with the right infrastructure. But it seems far
more reasonable to use satellite to fill in the gaps.
There is also the issue of where the white spaces spectrum is in the
highest demand. In general this will NOT be the remote areas, but
rather, the urban areas where DTV signal strength should be
relatively high. There is considerable interest in using the white
spaces for rural broadband services, but this may be accommodated
using properly designed services on channels that are adequately
separated to prevent interference.
Regards
Craig
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