Live Tests Explore Future of HD Radio

This year, in the months leading up to the NAB Show, Nautel had the chance to conduct live tests of our HD Multiplex technology, in association with PILOT and Xperi, and with the support of Beasley Media Group’s KKLZ(FM) in Las Vegas. (PILOT is NAB’s coalition of innovators, educators and advocates dedicated to advancing broadcast technology and cultivating new media opportunities.)
Our tests of all-digital FM radio culminated with a live demonstration at the spring NAB Show, where we were able to show 12 independent audio signals from a single FM station’s transmitter over the air.
Our initial concept for HD Multiplex was presented three years ago at the 2015 NAB Show. Using HD Multiplex, a combination of up to 15 audio streams and data services can reside within 600 kHz of signal bandwidth, or up to nine audio streams may be accommodated in 400 kHz of signal bandwidth. For more information on how HD Multiplex is implemented, visit Nautel’s HD Multiplex page at www.nautel.com/solutions/advanced-solutions/hd-multiplex.
It is important to note that this technology is still experimental at this point and has not been authorized for use. For our 2018 tests, Beasley Media Group obtained experimental authorization from the FCC.
Our 2018 live test was composed of three components: The first was a proof of concept for the Nautel HD Multiplex transmission scheme in which multiple IBOC digital radio signals are effectively stacked immediately adjacent to one another to achieve additional audio and/or data throughput.
The second, and main focus of the tests, was an evaluation of hybrid and all-digital transmission utilizing the MP5 mode, a mode that has always been an element of the HD Radio system but never authorized. The MP5 mode supports both hybrid and all-digital operation. (The most common hybrid IBOC Service Mode in use today is MP3, which permits use of up to five audio services but typically is used for three to four.)
The third component was our live demonstration at the NAB Show of a modified form of Nautel HD Multiplex, which allowed normal KKLZ analog operation as well as the transmission of four digital sidebands.
Two test periods were conducted prior to the show at KKLZ. The station was kind enough to suspend its analog carrier in some overnight periods to allow us to fully test all-digital transmission with up to 15 HD channels. During the testing period, we switched KKLZ from their normal MP3 hybrid transmission to MP5, adjusting the TPO to keep signal parameters within safe peak power limits both in hybrid analog/digital and all-digital tests.
F.RWorld