É a confusão total...

«XM wants to transmit its signal into HD Radios. The satcaster applied for a patent in December 2005 to send its signal - as well as that of MP3s, CDs and other digital sources - via IBOC. Such a scheme would keep its signal digital throughout the entire transmission path, and eliminate the need for analog FM modulator add-ons, it says in the application published this month by the U.S. Patent and Trademark Office.»

fonte: «XM Wants to Co-Exist With IBOC», 22/6/06, http://www.rwonline.com/dailynews/one.php?id=9242

Act a 26/6/06: Assim percebe-se (um pouco) melhor:

«Washington - Jun 15, 2006 - The idea of modulating an audio signal to a radio frequency so that it can be heard via a traditional radio receiver is not a new idea. When FM was young, there were plenty of converters to receive the FM and remodulate it to an AM frequency. Today, every media player offers an option to listen to the device via an FM radio.

In an ironic twist of the idea, XM Satellite Radio has filed a patent application that describes a system to receive an XM broadcast and then remodulate it on an FM HD Radio signal. The process would keep the audio signal in a digital form through the entire chain instead of converting it to analog at the input to the add-on transmitter.»

fonte: «XM Files Patent for HD Radio Converter», 19/6/06 Radio Currents Online