Time-aligned HD Radio
Dec 1, 2010 1:00 AM, By Chriss Scherer, editor
I received an anonymous tech tip from a reader concerning the alignment of the analog and digital streams of an HD Radio transmission. He has had some trouble with the Harris HD Radio Exporter, struggling with time-alignment and intermittent dropouts, especially when used with a T1 link. He reports that herculean efforts have been expended to isolate and correct the problem; but minor time slips still occur over days and weeks, which accumulate over time to a time-alignment problem requiring monitoring and tweaks.
Harris advised him to troubleshoot and co-locate the Exporter and exciter. While this is contrary to recommended practice, it seems to correct a host of little problems. It stands to reason that the data between an HD Radio Importer and Exporter would be less sensitive to time and bandwidth limitations. It requires that processing and delay be at the transmitter site along with a few other accommodations, but a few engineers have discovered that it makes HD Radio much more trouble free.
The reader does not know if the same situation exists with Exporters from Nautel, BE or Continental. Have you experienced any time alignment issues with your HD Radio equipment? If so, tell us about it.
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