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 *time* *title* *presenter(s)* *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 ~ ~ ~ *********************************** CONFIDENTIALITY NOTICE: This email message and any files transmitted with it contain confidential information intended only for the person(s) to whom this email message is addressed. If you have received this email message in error, please notify the sender immediately by telephone or email and destroy the original message without making a copy. Thank you. *********************************** ---------------------------------------------------------------------- You can UNSUBSCRIBE from the OpenDTV list in two ways: - Using the UNSUBSCRIBE command in your user configuration settings at FreeLists.org - By sending a message to: opendtv-request@xxxxxxxxxxxxx with the word unsubscribe in the subject line.