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HD Radio: Making the grade
At the end of November, the National Radio Systems Committee released its report recommending that the FCC authorize Ibiquity Digital Corporation's FM In-band On-channel (IBOC) digital radio broadcast technology as an enhancement to the current analog FM broadcasting system in the United States. The data reviewed was collected by Ibiquity, the Advanced Television Testing Center and Dynastat from eight stations in Annapolis, MD, Baltimore, MD, Columbia, MD, Las Vegas, New York, San Francisco, and Washington, DC.
The wording used by the NRSC to give its stamp of approval states that the IBOC system provides a “greatly reduced impact of multipath interference (for mobile, portable and fixed receivers alike); superior resistance to co-channel and adjacent channel interference; support for enhanced data services; [and] improved audio quality.” The recommendation to the FCC was that an FCC approval of the system would be “charting the course for an efficient transition to digital broadcasting with minimal impact on existing analog FM operation and no new spectrum requirements.”
I think most people were expecting the NRSC to give the thumbs up to FM IBOC. The concept of an IBOC system has been in the works for the past 10 years. I believe the NRSC did a thorough and honest job in making its evaluation. I don't even want to think about what would be happening right now had the NRSC found IBOC to be less then favorable. Once the AM report is made, the day will shortly follow when the FCC makes a ruling on IBOC.
Once word spread that the report was released, I started watching several discussion lists and talked with several people. IBOC is a topic that on its own can incite heated debates, and the news of the report fuels the fires. Some people were quick to point out flaws they saw in the test data. Since only a few stations broadcast a hybrid IBOC signal, some feel that the test does not represent a real-world demonstration for evaluating multipath, co-channel and adjacent channel interference. Others stressed that the tests used the AAC algorithm for the audio encoding, while Ibiquity plans to use a form of Lucent's PAC algorithm for the final system.
Informed, intelligent discussion is vital to coming to an educated conclusion. While the negative points do raise some good questions, these are points that have been considered along the way. These are tests and simulations, which take these factors into account. The key to the report is that it finds IBOC provides an improvement to the existing analog system. It does not claim that IBOC is the perfect system.
We are closer to an IBOC DAB standard, but we're not there yet. The promise of digital radio is wonderful. The AM report should be issued very soon, and I'm confident that the NRSC will also apply its seal of approval. In the end, the AM band has a more obvious gain than FM in improved fidelity.
I believe that for IBOC to be adopted by all stations, the FCC must require its implementation with specific dates to mark its transition. Without a mandate such as this, IBOC will flounder. The cost to stations for the hardware alone will be more than most are willing or able to pay. In addition, stations are still not enlightened with the licensing fees that will be passed on to them to use the technology.
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