OMVC Releases Tools for Mobile DTV On VHF Channels

The new "Predictive Model" for reception of High VHF mobile DTV signals will help engineers improve coverage and signal reception

By George Winslow -- Broadcasting & Cable, 12/21/2012 3:48:31 PM

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.