[opendtv] IEEE Broadcast Technology Society
- From: Mark Aitken <maitken@xxxxxxxxxx>
- To: OpenDTV <opendtv@xxxxxxxxxxxxx>
- Date: Thu, 02 Sep 2004 15:09:34 -0400
Look at 3:15-3:45PM...
<http://www.ieee.org/organizations/society/bt/symp/fullprogram.html>
Friday PM, October 15
DTV Interference and Reception Issues Session Chair -
Greg Best
***************************************
2:15-2:45PM
DTTV Reception in a Crowded Spectrum: Dynamic Range and Protection
Ratios from Interference by 1st Adjacent Channels
Oded Bendov, Consultant
With the introduction of DTTV, the number of channels assigned to each
market doubled even while the available spectrum was reduced. Planning
for DTTV service in a crowded spectrum requires power limits be placed
on all adjacent channels and, in particular, on 1st adjacent channels.
In this paper realistic power limits based on IM products generated at
the receiver by the desired and undesired signals are proposed. The
proposed limits are a function of the fundamental power in the desired
and undesired channels and the receiver's 3rd order intercept point
(IP3). This paper will show how the undesired spectral power density of
IM and XM components is estimated in the desired as well as in the
adjacent channels. The analysis will show that present D/U ratios
underestimate the expected interference from strong signals in many
markets, and that the receiver's IP3 should be at least 16dBm for the
dynamic range expected in the U.S.
***************************************
2:45-3:15PM
Interference Between Television Signals Due to Intermodulation in
Receiver Tuners
Charles W, Rhodes, Consultant
Interference between TV broadcast signals in the UHF band has been
mitigated since the inception of UHF broadcasting by regulating the
minimum geographic distances between transmitters based on certain
channels. These are the well known, but not well understood, UHF taboos.
With the introduction of DTV the use of these taboo channels and the 1st
adjacent channels to those already allotted to a community has become
necessary due to spectrum scarcity. Most of the taboos are due to
non-linear interference mechanisms which were, and still are,
characteristic of consumer receivers. Those mechanisms result in 3rd and
higher odd-order intermodulation (IM) products some of which fall in
another TV channel. Cross-modulation is a lesser problem than IM. The
author has conducted experiments on the extent to which 3rd order IM
products generated by TV signals on certain pairs of channels near the
victim channel can prevent reception of DTV signals on that channel.
This paper will attempt to quantify these interference problems.
***************************************
3:15-3:45PM
5th Generation DTV receiver solves ghost problems
Mark Aitken, Sinclair Broadcasting Group
Tim Laud, Zenith Electronics Corp
There has been a focused effort within the TV broadcast industry to move
DTV receiver technology "state-of-the-art" forward to better deal with
some of the more difficult and complex receiving environments. In this
paper, we detail the approach taken which today provides the broadcast
industry with a "breakthrough" 8-VSB receiver product that has "cleared"
the bar of expected performance for the simple reception of over-the-air
DTV in most complex environments. Field evaluation data will be
presented to confirm the conclusions. Providing correlation of results
with laboratory simulations and tests with those "real world" conditions
in various field trials conducted by multiple parties will allow this
technology to achieve quick acceptance in the marketplace.
***************************************
4:00-4:30PM
Impact of Impulse Noise on DTV Reception on Low VHF Channels
Charles Einolf, Consultant
In this paper we will examine the basis of impulse noise, the occurrence
of impulse noise in the field, and the impact of impulsive noise on DTV
reception in the low-VHF TV band. Ambient electromagnetic noise, which
may adversely affect DTV, is often impulse in nature and is different
from thermal Gaussian noise produced within the receiver system itself.
Most studies to date have dealt with the impact of impulse noise on
narrow-band communications. DTV presents a greater challenge since
impulse noise is broadband in nature and involves wide excursions in
pulse amplitudes. The impact on DTV is not a total loss of service where
increasing signal strength will solve the problem of reception. Impulse
noise causes intermittent loss of both audio and video that is
subjectively detrimental to quality reception. This paper explores field
experiences with impulse noise and the limitations of DTV receivers to
handle the interference.
***************************************
4:30-5:00PM
Interference Analysis of Co-Sited DTV and NTSC Translators
Gary Sgrignoli, Consultant
DTV service has begun in all the major urban areas within the U.S. but
has yet to significantly reach the rural areas. Often, translators are
the only means of providing free, over-the-air service to people living
in these areas. One challenge is that specific rules for operation and
spectrum allocation exist for full-service stations in urban areas, but
there are currently no rules for DTV translator stations in rural areas.
Another challenge is overcoming the scarcity of spectrum that exists
under the old analog taboo interference rules. A key to overcoming these
challenges is to determine interference parameters in the form of D/U
ratios that will allow many DTV and NTSC signals to co-exist. Also,
co-sited analog and digital translator sites utilizing low radiated
power can be used for adjacent/taboo channel operation (NTSC next to DTV
or DTV next to DTV) if careful engineering and planning are employed.
Even 1st adjacent channel operation can be accomplished if proper
effective radiated power (ERP) ratios are selected. This presentation
shows that, assuming application of the proposed "simple" emission mask,
a 10dB NTSC-to-DTV power ratio and a 0dB DTV-to-DTV power ratio are
acceptable at a co-sited repeater site in order to avoid receiver
interference among the co-sited signals.
/(End of Symposium)/
--
Regards,
Mark A. Aitken Director, Advanced Technology
***********************************
Sinclair Broadcast Group
10706 Beaver Dam Road
Hunt Valley, MD 21030
Business TEL: (410) 568-1535
Business MOBILE: (443) 677-4425
Business FAX: (410) 568-1580
E-mail: maitken@xxxxxxxxxx
Text PAGE: page.maitken@xxxxxxxxxx
www.newscentral.tv
www.sbgi.net
===================================
"There never was a good war
or bad peace...."
~ ~ ~ Benjamin Franklin ~ ~ ~
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