A research group at the San Diego Supercomputer Center is using specialized hardware configurations to support wireless links that span up to 72 miles – using the same standard as Apple's AirPort.

The San Diego County High Performance Wireless Research and Education Network (HPWREN) last month installed a 72-mile WLAN to link seismographic data collection equipment installed on San Clemente Island to the supercomputer centre's facility in San Diego.

Hans Werner-Braun, a researcher at the supercomputer centre, said standard 802.11b WLAN gear operating in the unlicensed 2.4GHz frequency serves as the baseline hardware for the network.

The solution uses non-standard equipment. For example, HPWREN technicians installed high-gain, 2-foot parabolic antennas at both ends of the link to provide an additional boost to the signal.

HPWREN is using Proxim's Orinoco routers and bridges as part of the WLAN. Although the devices support a raw data rate of 11Mbps, the extreme distance cuts the actual throughput on the link to San Clemente Island to 1Mbps, Werner-Braun said.

Robert Ma, a product manager at Proxim, estimated that the new installation had a fixed cost of about $3,000. The WLAN is used to carry data from a seismograph data logger and Global Positioning System receiver to the supercomputer center, which then sends the information to a statewide seismic data tracking network.