The National Radio Systems Committee, a standard setting organization sponsored by the National Association of Broadcasters and the Consumer Electronics Association, adopted an IBOC standard, designated NRSC-5A, in September 2005. NRSC-5A sets forth the requirements for broadcasting digital audio and ancillary data over AM and FM broadcast channels. The standard and its reference documents contain detailed explanations of the RF/transmission subsystem and the transport and service multiplex subsystem for the system. Copies of the standard can be obtained from the NRSC at http://www.nrscstandards.org/standards.asp.
The NRSC standard setting effort was preceded by an extensive test and evaluation program for both the AM and FM HD Radio™ systems. After an exhaustive series of laboratory and field testing conducted under the supervision of the NRSC and an industry evaluation, the NRSC endorsed the FM IBOC system in 2001and the AM IBOC system in 2002.
Background: In 1999, the NRSC developed its first set of IBOC test guidelines, which were designed for testing prototype IBOC systems. In late 1999 and early 2000, USA Digital Radio and Lucent Digital Radio, submitted to the NRSC reports on iBiquity’s predecessor’s testing of the IBOC technology. These reports confirmed the ability of IBOC technology to provide upgraded audio quality and robustness in both the AM and FM bands without causing harmful interference to existing analog broadcasts in those bands.
During 2000 and early 2001, the NRSC continued its analysis of IBOC technology. In December 2000, the NRSC adopted new FM laboratory and field test procedures to be used for final IBOC validation testing. In April 2001, the NRSC adopted new laboratory and field test procedures for AM IBOC testing.
During 2001, iBiquity completed an extensive test program of its FM and AM technology. These tests followed the NRSC test procedures and were conducted using independent laboratories in Alexandria, Virginia, Cincinnati, Ohio and Austin, Texas. In addition, field tests were conducted using seven commercial and one experimental FM station and three commercial and one experimental AM station. NRSC observers actively participated in and oversaw all these tests. The tests were designed to assess both the IBOC system’s performance in a variety of interference and impairment scenarios typically found in the real world and the potential impact of the IBOC system on analog operations of the host station as well as co- and adjacent channel analog stations. The tests involved the use of analog receivers representing OEM auto, aftermarket auto, home and portable receivers. Simultaneous tests were conducted on the digital and analog receivers to allow for direct comparison of digital and analog broadcasting. In addition to objective measurements obtained in the lab and field, these tests also involved an extensive subjective evaluation of digital and analog audio samples. In the case of FM, more than 480 listeners subjectively evaluated thousands of audio samples.
The complete iBiquity FM test report can be found at http://www.nrscstandards.org/drb/fmtestdata2.asp. The complete iBiquity AM test report can be found at http://www.nrscstandards.org/drb/amtestdata.asp.
For supplemental information to the NRSC Standard and Evaluation Program, click here.
