04.20.2007 12:00 AM
Mobile ATSC DTV Heats Up at NAB 2007
Some of the most talked about RF technology demonstrations at this year's NAB were on the streets around the convention center, not on the exhibit floor. Proponents of competing technologies for mobile TV using U.S. broadcasters' 8-VSB DTV signal took attendees on bus rides around Las Vegas to demonstrate how well their systems performed.
LG and Harris demo took the most demanding route. Their bus ride showed their MPH technology worked even driving under the convention center overpasses and along the Las Vegas Strip. Samsung and Rohde & Schwarz demonstrated A-VSB around the Strip at CES earlier this year, but at NAB, the companies focused on higher speed routes in somewhat less demanding neighborhoods, avoiding the tunnel at the convention center. While both mobile demonstrations used signals from transmitters located on Black Mountain, Samsung/Rohde & Schwarz also demonstrated a single frequency network (SFN) using A-VSB technology without the robust stream. I found the SFN provided excellent reception around the convention center as well as at my hotel, even though the transmitters on the Strip were running only 100 watts, and the one at the convention center was generating only 10 watts.
Unlike LG/Harris, riders on the Samsung/Rohde & Schwarz bus were able to play with actual handheld A-VSB receivers. While these receivers lacked the second-generation A-VSB chip recently developed by Samsung, performance was impressive inside the bus. It was difficult to break the signal, even with one of the diversity antennas collapsed and folded against the receiver. Signal strength did not appear to be an issue here. While the A-VSB demo route was less impressive, the A-VSB proponents provided far more technical information on their system. It has been submitted to ATSC for consideration as a standard.
At a standing room only session on mobile TV, attendees pushed LG and Harris for more information on the MPH system, while Triveni (a division of LG) showed test results demonstrating that nonreal-time delivery of data to vehicles is possible with the ATSC transmission system in use today.
As I've written several times before, I believe delivering TV programs to portable, handheld and mobile receivers will be essential for the future of free over-the-air TV, as the majority of viewers use cable and satellite TV to receive programming for their fixed TV sets. Look for a more detailed discussion of mobile TV in my June RF Technology column in TV Technology.