08.04.2010 03:02 PM
Originally featured on BroadcastEngineering.com
NPRM seeks input on DTV signal strength measurement
How should the FCC go about determining the ability of TV viewers in specific locations to receive over-the-air signals from local television stations for the purpose of deciding whether or not a direct-to-home satellite TV service should be allowed to import distant network TV stations?
That’s the question a new Notice of Proposed Rulemaking seeks to answer by seeking input on a wide variety of assumptions about the similarities and differences between NTSC and ATSC signal propagation and reception.
The Satellite Television Extension and Localism Act (STELA) of 2010, enacted Feb. 27, directed the FCC to develop a predictive model that can be used to determine whether viewers at specific locations receive an off-air DTV signal with an antenna at the appropriate signal intensity. The act also instructed the commission to rely upon the Individual Location Longley-Rice (ILLR) model used to develop the predictive model for analog TV signals in setting up the model for DTV signals.
The commission is seeking comment on modifications it is proposing to the ILLR model to make it suitable as a method to predict DTV signal strength. The modifications, detailed in an appendix to the notice, are intended to make the model suitable for measuring signals strength for digital full-power, Class A, low-power and translator stations.
In Appendix B of the NPRM, an Office of Engineering & Technology Bulletin lays out the ILLR computer program for predictive DTV coverage. Specifically, the ILLR computer program “computes the predicted signal strength of DTV stations as received over-the-air at individual viewing locations.” The program must be used in combination with terrain elevation data and a database describing building structures and vegetation, the bulletin said.
In the notice, the commission noted that the decision of Dish Network to launch local-into-local service in all 210 DMAs will dramatically reduce the circumstances in which a subscriber will need access to a distant broadcast TV station.