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While one might be optimistic that the multipath tests conducted at WAEB in Allentown would add to the body of knowledge concerning multipath, the first round of tests yielded so many anomalies that it would appear dangerous to base conclusions on the data gathered due to severely scalloped- antenna pattern measurements. Opinions on the cause ranged from fresnel reflections, to reflections from the mountain range adjacent to the WAEB transmitter, to co-channel interference. Perhaps the best data is the reflection delay pulses gathered by Delco (presumably to work on exact diversity receive antenna placement for future GM models). Initial observations from the second round tests were largely subjective, but nonetheless indicated multipath is worse with vertical radiation. |
What is needed is a carefully designed U.S. study to evaluate multipath distortion at several scores of locations with various modes of transmission and reception polarization. Such results would either corroborate or refute the European and Canadian studies. For either outcome, public radio's needed insight into the utility of TV-6 vertical deployment in varying terrain would be significantly improved.
The costs to conduct the study will be the next hurdle in the polarization debate. NTIA
staffers have been told by their test facilities in Colorado such a project would cost
about $200,000. Despite all of those zeros left of the decimal, given the rugged terrain
in many areas unserved by public radio, the costs of not knowing the tradeoffs in advance
may be higher still.
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