4.9 GHz ground, airborne systems co-exist
LONG BEACH, Calif. — A demonstration of 4.9 GHz systems last month showed that airborne systems — typically used by helicopters to provide video coverage of an incident — could perform adequately without disrupting ground-based systems.
It had been feared that interference caused by airborne systems that would disrupt ground-based systems would limit the overall effectiveness of 4.9 GHz systems. The FCC set aside the 4.9 GHz band specifically for public-safety wireless broadband to enable high-data rate applications such as video surveillance.
The test was conducted under an experimental FCC license obtained by event organizer Mike Doble, public-safety marketing manager for Proxim Wireless Networks. The license — which took about five months to obtain — was the second issued by the FCC for an airborne 4.9 GHz application. The first was issued to the Democratic Party for its 2004 convention.
The event was hosted by the city of Long Beach, whose police and fire departments made available personnel and facilities. Two mock incidents were staged, one a police chase and the other a car crash and resultant fire. Two helicopters hovered over the two scenes and transmitted video footage using 4.9 GHz systems in real-time to the police department’s incident command center. One of the helicopters used an omnidirectional antenna while the other used a point-to-point steerable antenna.
Real-time video also was transmitted by 4.9 GHz systems mounted in police vehicles on the ground. While Doble acknowledged, “some of the bugs still need to be worked out,” both the airborne and ground-based systems provided good-quality video with only sporadic and short-lived breakup.
The video was quite good considering that it was provided by temporary infrastructure, said Miles Cowan, chief technical officer for Insight Video Net, which installed the systems used during the demonstration. “A fixed infrastructure would have more access points and would be more robust,” Cowan said.
