U.S. HDTV Intolerant of MultipathJune 18th Fact-of-the-Day
Europe and the United States adopted different High-Definition Television (HDTV) transmission methods. Europe adopted a Coded Orthogonal Frequency Division Multiplexing (COFDM) method. The U.S. adopted an 8-Level Vestigial Sideband (8-VSB) method. The U.S. method requires less transmitter power for a given signal-to-noise ratio and packs more bits of data into each transmission second (19.4 compared to 18.66 Megabits), but the European method is much more tolerant of multipath signals. It is rare that UHF signals don't reradiate off buildings, power lines, or other things and arrive via multiple paths. The result with analog television is one or more ghost images. The result with the U.S. FCC mandated HDTV method can be no picture at all even though the multiple signals are strong. ©2005 Martek International All rights reserved.
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