ION Media Networks (formerly Paxson Communications Corp.) and Richland Towers have announced the completion of successful testing of a single-frequency network (SFN) for New York City. In brief, a SFN uses multiple synchronized transmitters at different locations, operating on the same frequency, to replicate the coverage of a traditional "big stick" single-transmitter system. At least one such system for digital television broadcasting is operating in an initial configuration for public television station WPSX at Pennsylvania State University. From the ION press release:
... The Richland DTx single frequency network consists of a main, high-powered “hub” site in West Orange, N.J., providing coverage to most of the market area; and five low-power DTxT sites that serve the remainder of the area. Multiple rounds of testing were conducted at the main West Orange site and a transmitter site at 4 Times Square in Manhattan. The test teams obtained field measurements from the two sites and compared them to measurements taken from five stations transmitting from the Empire State Building. Field strength, signal quality, reception and all other parameters for the DTx network were comparable to or better than those from the Empire State stations. The test results are being made available to other interested broadcasters. ...
Link to the related article in Broadcast Engineering.
Public television stations frequently operate with transmitters that are not located at the cluster of antennas used by commercial television stations in a market (my Pullman, Washington station is one such) and therefore operate at a disadvantage in terms of receive antenna orientation. SFNs offer a solution to this problem. --Dennis