IBiquity Provides Test Data to NRSC
Aug 9, 2001 12:00 PM, Chriss Scherer, editor
Columbia, MD � IBiquity Digital announced that it has supplied its final FM test data to the National Radio Systems Committee (NRSC). The report is 600 pages long and covers the data gathered by the Advanced Television Technology Center. This data will be used by the NRSC to evaluate the in-band on-channel (IBOC) system developed by iBiquity as a proposed transmission standard for digital radio in the United States.
The NRSC is a standard-setting committee formed by the NAB and the Consumer Electronics Association (CEA).
IBiquity held a press conference to announce that the test results conclusively show that its implementation of FM IBOC, called iDAB, shows a marked improvement in four distinct areas of radio transmission. IBiquity also commented that it believes that these tests are the most comprehensive of any tests of their kind.
The test program evaluated audio quality by using 600 separate sound samples and 120 listeners. The IBOC signal was selected to have a better overall sound in all musical genres. These tests included transmission obstacles such as multipath and other adverse transmission conditions.
The coverage parameters were evaluated using eight stations that were deemed to be representative of stations in the U.S. The stations were WETA Washington, DC, WPOC Baltimore, WHFS Annapolis, WNEW New York, WWIN Baltimore, KLLC San Francisco, KWNR Las Vegas and a low-power test station at the iBiquity offices in Columbia, MD. The digital signals were transmitted at a power level that was 1% of the analog power level at each station. It was deemed that the IBOC coverage even at this power level provided better audio performance. Each of these facilities provides varying terrain and other transmission conditions.
Robustness is a subjective evaluation of analog and digital receivers. The received signal strength is reduced and the resulting audio performance is considered. IBiquity reports that the digital performance remained strong while the analog signal failed.
The last evaluation determined compatibility between the analog and digital signals. Interference between the two carriers to themselves and between the test station and other stations on first and second adjacent frequencies was evaluated. The test results showed that IBOC will have no meaningful impact on analog operations.
All these tests used the AAC audio encoding algorithm, which was a part of the USA Digital Radio system being developed before USADR and Lucent Digital Radio merged to form iBiquity. The final test system will use Lucent�s PAC algorithm. IBiquity was granted permission to make these tests despite this obvious difference in the final system plan. According to iBiquity, the encoding algorithm is a simple substitution. Bob Struble, CEO and co-chairman of the board of iBiquity, referred to the change in algorithms as �plug and play.� Additional tests with PAC will be performed by iBiquity.
These tests only covered the FM system. AM tests are currently underway. AM test results are due in October 2001.
IBiquity is hopeful that the NRSC will make its evaluation and subsequent endorsement to the FCC by the end of this year so a ruling can be made and broadcast equipment can be made available for display at NAB2002. IBiquity would like to see a consumer equipment rollout made for CES 2003.