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OMVC Releases New Tools for Mobile DTV Deployments

In a bid to simplify the process of deploying mobile digital TV services and to encourage manufacturers to produce more mobile DTV capable devices, the Open Mobile Video Coalition (OMVC) has released several new studies and tools.

The information and new tools will help Mobile DTV consumer electronics product manufacturers enhance Mobile DTV reception by reducing the need for expensive field testing of new mobile DTV consumer products and will make it easier for TV station engineers design robust mobile DTV systems, explained OMVC executive director Anne Schelle in an interview.

Mobile DTV is already available from some 75 broadcasters and the OMVC is forecasting that Mobile DTV service will reach two-thirds of the viewing public over the next year. 

While mobile DTV is designed to be transmitted alongside the same digital TV broadcasts that provide local news, weather, traffic, sports, and other programs in HD, the signal qualities of Mobile DTV are quite different from HDTV transmissions because antennae in Mobile DTV receivers are usually lower to the ground and always on the move.

To help consumer electronics manufacturers and stations deal with those differences, the OMVC has been working to deal with a number of issues and has released several documents and tools.

One is the Mobile DTV Propagation Study, which is available on its web site. It reviews the reception characteristics of the mobile video service and provides details about the "RF Capture" program service for device manufacturers.

The two other documents released by the OMVC today are a recommended practices document for deployment of Electronic Service Guides and a presentation about the most likely broadcast scenarios for mobile DTV services, including 11 use cases for multiple channels at varying qualities of transmission.

These use case scenarios will help broadcasters provide better signals for the types of programming they plan to air, be it sports or news and entertainment.

The OMVC has also developed a new Predictive Model for reception of UHF (channels 14 to 51) mobile DTV signals. The model is intended to predict signal coverage in a wide array of mobile devices, including automobiles with an antenna mounted on the vehicle and handheld units operating both outdoors and indoors.

Broadcaster radio-frequency (RF) experts can use this new model to predict future coverage of existing or future transmition facilities so that they address problems with their coverage. 

Schelle noted that the new mobile propagation model represents an improvement over existing techniques. "With information about the local terrain, antenna height, frequency, and polarization as well as details about the receiver and atmospheric conditions," the station can predict signal strength for mobile broadcasts with this model," Schelle explained.

In the future, the OMVC will be working to further improve the Predictive Reception Model so it will cover additional issues, such as the effects of tall buildings and VHF reception.

Since March, OMVC has also coordinated been recording or "capturing" live over-the-air Mobile DTV radio-frequency (RF) signals in the Washington, D.C. market as part of an "RF Capture" effort that will provide broadcasters with a better understanding their reception environments and help mobile device product developers improve their products. 

Broadcasters and product developers can play back these profiles from the RF Capture Catalog in their labs for more thorough analysis and evaluation of the Mobile DTV RF environment to improve the quality of signal and coverage.

"We've recorded more than 290 different sequences, each about a minute and a half long and each at ‘pedestrian' height and speed and also at the usual TV signal measurement of 30 feet off the ground," Schelle explained in a statement. "Our members and others will have access to these signals to both improve broadcast transmissions and help consumer electronics manufacturers design and test new products without the expense of on-site field trials. The Washington, D.C. RF captures are just the first step. Next, we're accumulating similar data in Texas and will make those broadcasts available as well."