The head of a new advocacy group determined to free TV broadcasters from government rules mandating 8VSB as the sole DTV modulation scheme authorized for use in the United States has applied for an experimental license from the FCC to put a five-cell, four-channel OFDM-based digital TV transmission system on-air in the Portland, OR, area.
If granted, the license would clear the way for Greg Herman, president on the newly formed SpectrumEvolution.org advocacy group and president of Portland-based LPTV broadcasting company WatchTV, to demonstrate that OFDM transmission can exist within a portion of a 6MHz channel devoted to transmission of an ATSC signal.
“We’re doing this for the purpose of showing that OFDM can behave nicely and be a good neighbor next to anything ATSC,” Herman said. “Given the complexity and self-analytical nature of OFDM, I have every belief that it will not interfere. In fact, it will work very nicely inside a world populated with both ATSC and OFDM.”
Currently, WatchTV is conducting mobile ATSC (A/153) experiments with the help of Harris. If the FCC grants the experimental license, WatchTV may be the only place in the world where both mobile ATSC and an OFDM single-frequency network aimed at mobile reception will be in use simultaneously, he said.
CMMB America, an organization backing deployment of Converged Mobile Multimedia Broadcasting, will assist WatchTV with its OFDM implementation if authorized. Currently, a CMMB network is being deployed in more than 350 cities in China. According to Herman, not only does OFDM offer technical advantages over the mobile ATSC, but an ecosystem of some 500 devices exists today. An international CMMB demodulator chip with support for 8MHz, 6MHz, 5MHz and 2MHz is expected to be available within 90 days, he added.
On Nov. 17, Herman demonstrated to representatives of the Office of Engineering and Technology at FCC headquarters in Washington, D.C., OFDM modulation equipment and an ecosystem of some 20 devices. During the demo, Herman used a test system to transmit eight streams of video, and gave a presentation on how an out-of-band backchannel could be integrated with the technology to give a future U.S. deployment interactivity.
For Herman, allowing broadcasters to freely choose the digital modulation scheme of their liking is exactly what’s needed for broadcasters to play a significant role in advancing the goals laid out in the FCC National Broadband Plan.
“Broadcasters should play a vital role in implementing the National Broadband Plan, but they need to unleash the beast,” he said.
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