The Open Mobile Video Coalition (OMVC) is
releasing new tools that are designed to help broadcast engineers improve the
reception of mobile DTV signals on High VHF channels 7 to 13.
Based
on extensive research, the new "Predictive Model" for reception of VHF mobile
DTV signals is designed to help engineers predict signal coverage for a number
of devices. These include automobiles with an antenna mounted on the vehicle;
handheld units operating outdoors; and handheld units operating indoors.
The
new report complements an earlier UHF Predictive Model that detailed reception
characteristics for broadcasters operating on channels 14 and higher.
The
new 20-page VHF Propagation Model report can be downloaded here
Anne
Schelle, executive director of the OMVC noted in an interview that the report
was part of the group's mission to help broadcasters better understand the
technical issues involving mobile DTV broadcasts.
While
these broadcasts use existing broadcast spectrum, "the signal qualities of
Mobile TV are quite different than HDTV transmissions,
because reception antennae in Mobile TV receivers are usually lower to the
ground and always on the move," she noted in a statement. "We want broadcasters
transmitting on VHF channels 7 through 13 to be aware of what transmission
methods best serve a viewer who is walking, or a passenger who is watching
while riding in a car."
To
do that, she added that "we've opted for a ‘semi-empirical' method that uses a
blend of actual field reception data and theory. 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," Schelle said.
The
OMVC is scheduled to integrate its activities with the National Association of
Broadcasters by the end of 2012. The move reflects the fact that the work on
mobile DTV has moved from a technical phase to a period where these services
are being rolled out to consumers, Schelle said. The incorporation of OMVC into
the NAB will allow the mobile DTV efforts to draw on
the more extensive resources available at the NAB.
The
Dyle TV service backed by the Mobile Content Venture has already rolled out in
35 markets and the Mobile500 Alliance is working on another mobile DTV service.
