(Business 2.0) – When catastrophe strikes, chaos is the only constant. Silicon Valley-based PacketHop turns that weakness into a strength with software that transforms ordinary Wi-Fi cards, PDAs, and laptops into the components of a flexible communications system for emergency workers.

Traditional hub-and-spoke networks (such as mobile-phone systems) can be overwhelmed by too many users. But with help from military-grade mesh networking technology licensed from think tank SRI, PacketHop allows rescue personnel to bounce data wirelessly from one user to another using off-the-shelf hardware. Each user becomes a node, effectively strengthening the network as it grows. The result is a data grid that thrives on chaos.

Best of all, "it's cheap!" says PacketHop chief technologist Ambatipudi Sastry. The company says users can build a network for half the cost of the proprietary data links now used by many police and fire departments. And unlike with the older systems, which rely on custom base stations and networking protocols, any emergency worker with a Windows laptop and a Wi-Fi card can plug in at the scene by wirelessly downloading PacketHop's software.

In a successful test of PacketHop's system in February, teams from 13 public safety agencies worked together to tackle a simulated disaster at the Golden Gate Bridge in San Francisco. PacketHop hopes to begin selling its software by the end of the year. -- BRIAN CAULFIELD