The Axcera Axciter intelligent modulator, which is at the heart of WNYZ-LP's BET system.
QUEENS, N.Y.
Island Broadcasting operates several television stations, including WNYZ-LP, which serves New York City on Channel 6 from the Citibank building in Queens. We started up as an analog low power station, but recently flash cut to digital operation.
Before making the digital conversion, we wanted to be sure that our entire audience would be served after the switch. Since the aural carrier of VHF Channel 6 is frequency modulated and centered at 87.75 MHz, many FM receivers can tune our audio. We knew that a significant portion of our audience depended upon radio reception of our signal and we were very concerned about the conversion to digital, as this would eliminate the analog FM carrier.
WANTED TO KEEP AUDIO-ONLY FM AUDIENCE
While converting to a DTV signal would allow us to continue to provide programming to our television viewers, we needed a way to retain our analog FM aural carrier in order to avoid the loss of our "audio-only" audience.
We considered converting to digital and then broadcasting a separate analog aural carrier on top of the digital signal by adding a second transmitter and antenna that would be cross-polarized with the signals from the television transmitting antenna. However, we were concerned that the strong analog FM aural carrier could reduce the ability of digital receivers and DTV conversion boxes to decode the video signal. We even considered delaying our conversion to digital and remaining on the air with our analog signal, as there's no mandate for low power stations to convert, but concluded that this would result in a potentially significant loss of television viewers.
AXCERA TECHNOLOGY PROVIDES SOLUTION
Fortunately, Axcera was able to offer a solution through the use of their patented Bandwidth Enhancement Technology (BET). This is designed to "move" information from one part of the ATSC channel to another, effectively reducing the required signal bandwidth without reducing the useable data rate. We recognized that this technology would allow us to convert to DTV and continue to operate an analog aural carrier while minimizing any interference from the aural carrier to the DTV signal.
Axcera offers BET as an option to its Axciter intelligent modulator platform, which can be added to any Axcera transmitter or used as a retrofit for non-Axcera transmitters. We purchased an Axcera DT325B digital VHF transmitter with the Axciter/BET option, which was installed last November. Since then we have successfully broadcast a digital television signal with our Axcera transmitter, while keeping the analog aural carrier on the air with the use of a separate analog FM transmitter. The digital ATSC signal is excellent, providing our viewers with improved reception when compared with the analog NTSC television signal, even in the presence of the analog aural carrier. Thanks to the narrowband BET digital signal, it's possible to have the best of both worlds.
The system is currently operating under a license application for digital television broadcasting, plus an ancillary service. We may also petition the FCC to consider permanent rules that would allow any digital television station to narrow their digital occupied bandwidth through the use of BET, making room for other services within any DTV channel.
Richard D. Bogner is founder of the Bogner Broadcast Equipment Corp., a manufacturer of broadcast antennas. He is also the founder of Island Broadcasting Co., licensee of five LPTV stations. He may be contacted atrdbogner@aol.com. Ron Scotto is chief engineer at Island Broadcasting and has been a broadcast engineer for more than 30 years. He may be contacted atGSDS@aol.com.
For additional information, contact Axcera at 800-215-2614 or visitwww.axcera.com.
