OMVC Offers Mobile DTV Reception Models and Tools
June 28, 2011
NEW YORK: The original mobile DTV consortium is offering
up a series of signal analysis tools to help broadcasters and electronics makers
deploy mobile over-the-air TV. The Open Mobile Video Coalition said it’s releasing
signal propagation and reception data among other items.
The OMVC’s new predictive model for mobile DTV reception in UHF Chs. 14 to 51 is
intended to anticipate signal coverage in automobiles with an antenna mounted on
the vehicle, in a handheld unit operating outdoors, and a handheld unit operating
“While there are different models used to predict broadcast signal coverage, we’ve
opted for a ‘semi-empirical’ method that uses a blend of actual field reception
data and theory,” OMVC Executive Director Anne Schelle said. “With information about
the local terrain, antenna height, frequency, and polarization as well as details
about the receiver and atmospheric conditions, we can predict signal strength for
mobile broadcasts with this model.”
The data was used to create maps illustrating the best areas for mobile DTV reception.
Further field testing in cars “showed the predictive model to accurately correlate
to actual conditions,” the OMVC said. Future versions of the predictive reception model
will consider elliptical and circular polarized transmission antennas and the effects
of tall structures near receivers. It also will provide more details on predictive
VHF reception, the group said.
OMVC launched a signal-capture program in March to build a model of a reception
environment. The group is recording live over-the-air mobile DTV radio-frequency
signals in the Washington, D.C. market and cataloging them to create a “signal library.”
This “RF Capture Catalog is a collection of profiles that allow broadcasters and
product developers to play back these profiles in the laboratory for more thorough
analysis and evaluation of the mobile DTV RF environment,” the OMVC said. “Different
captures of RF television signals will help broadcasters determine the relative
performance between the two services and their expected coverage.”
Schelle said 290 signal sequences, each about 90 seconds long, had been recorded
at “pedestrian height and speed,” and also at 30 feet off the ground. The
signals were captured on Ch. 24 at a total of 48 sites in D.C. Each one is
around 3.7 GB. Data being collected now in Dallas will be added to the catalog.
The OMVC is offering rental of a Adivic RF recorder/player to interested
parties, including standards bodies.
The group is also releasing a recommended practice for deployment of an Electronic
Services Guide, plus presentations on launch scenarios that include 11 use cases.
The OMVC said around 75 broadcasters have made the upgrades to transmit mobile DTV.
The group is forecasting that the service will reach more than two-thirds of the
“viewing public” over the next year.
~ Deborah D. McAdams