At the NRSC, a Year of Acronyms
Members of the National Radio Systems Committee are looking at designing and conducting lab and field tests for AM and FM broadcast transmission schemes as well as creating Radio Broadcast Data System user guidelines.
The NRSC is a standard-setting body sponsored by NAB and CEA.
The AM and FM Analog Broadcasting Subcommittee is exploring FM stereo transmission using single-sideband suppressed carrier modulation, or FM SSB. While the concept has been around for decades, only recently has technology been available to implement it economically, advocates say.
NRSC Chairman Milford
Smith, left, vice president of radio engineering for Greater Media, talks with
former NRSC Chairman Charlie Morgan. Photo by Jim Peck.
A task group headed by Bert Goldman, vice president of engineering of Independence Broadcast Services, wants to initiate formal lab and field-testing of FM SSB to quantify perceived benefits of the technology and to discover any downsides. Members would determine what kind of testing would be done, where it would be done and who would pay, according to NRSC Chairman Milford Smith, vice president of radio engineering for Greater Media.
There’s a perception that, in some cases, FM SSB reduces multi-path degradation in existing receivers. FM SSB has been tested informally at Greater Media’s Boston cluster.
“We’ve got enough anecdotal evidence now so the group came together and decided to go forward,” he said, to try to quantify what kinds of multipath potentially can be reduced by FM SSB transmission.
Other claims of improvement will be explored too. They include better protection of analog and digital SCAs as well as improvement in signal to noise, the latter with specially designed receivers.
The ultimate goal would be to learn whether FM SSB offers enough improvement to ask the FCC routinely to allow its optional use. Right now, stations need an STA to transmit in this mode.
Power and data
A similar task group was formed to review the AM power-saving Modulation-Dependent Carrier Level transmission algorithm.
The group, led by Nautel Head of Engineering Tim Hardy, is investigating the technology’s compatibility with HD Radio technology. There are AMs on the air now with MDCL technology from both Nautel and Harris.
The goal would be to allow routine deployment without experimental FCC authority.
The RBDS Subcommittee is drafting two user guidelines.
Previously the group adopted an RBDS guideline that “harmonized” FM RDS and HD Radio data receiver displays so they looked the same. Now the group is looking at how stations use RDS data in a broader sense, such as transmitting traffic data.
“Lots of folks have tried lots of different things,” said new Subcommittee Chair Dan Mansergh, “and we want to collect all that industry intelligence into one place and say ‘Here’s the best thinking about this right now.’” Mansergh is director of radio engineering and media technology at KQED, San Francisco.
The group is discussing an accompanying guideline that covers metadata distribution throughout broadcast networks.
The RBDS Subcommittee hopes stations use the guideline procedures so that consumers will have a better user experience. The RDS data displays on a receiver would look similar from station to station, without errors, holes or mis-transmitted information, according to Mansergh and Smith. The subcommittee hopes to wrap up its work by the fall Radio Show.