It had never been done before: a major assault launched from 658 miles away, at sea. Task Force 58 - initially composed of 2,000 Marines of the 15th Marine Expeditionary Unit - landed in southern Afghanistan in November 2001 and established a base camp 55 miles south of the Taliban stronghold in Kandahar. The Operation Enduring Freedom ground campaign against al Qaeda and the Taliban was under way, with the new base - Camp Rhino - as its initial hub.

But the assault created significant challenges in communications because of the great distance between Task Force 58 and the sea base that launched it - an amphibious ready group in the North Arabian Sea. Although the task force had tactical satellite communications with its base, bandwidth was limited and commanders at Camp Rhino initially had to rely on aircraft such as U.S. Navy P-3C patrol planes and U.S. Marine Corps KC-130 transports to relay communications to commanders on ships. Eventually satellite dishes were brought in for wideband communications.

The mountainous terrain proved even more challenging. Backpack satellite communications were used by ground troops, but they had to restrict the number of radios in use due to bandwidth limitations.

To resolve these problems, the Marine Corps Warfighting Laboratory, Marine Corps Base, Quantico, Va., developed a new portable, over-the-horizon communications system that is being tested by Marine units in Iraq to assess its link between command centers, fire-support commanders and tactical units ashore during operations.

The Expeditionary Tactical Communications System (ETCS) is a voice and data link between tactical units -down to the company, platoon or squad level - and their combat commanders. It is envisioned as a solution for rapidly advancing units that outstretch their ability to communicate with commanders.

The new technology may lead to the development of a lightweight, flexible network that will provide reliable communications from a sea base to the expeditionary units farthest inland.

The ETCS is a 1.5-pound handset integrated with a Global Positioning System receiver and a group radio controller to manage voice and data traffic. Built by General Dynamics C4 Systems, Scottsdale, Ariz., the handset can be connected with data terminals, Hammerhead Tablet ruggedized laptop personal computers and handheld Commander's Digital Assistant, a militarized personal data assistant.

The vest-mounted handset - which can operate for 12 hours on the charge of a 1.5-pound battery - is capable of encryption and can conduct voice and data transmission and reception simultaneously over a single channel. The handset also can be connected to helmets, mounted on vehicles and linked to unmanned remote sensors.

The ETCS handset communicates via the constellation of Iridium mobile satellites, enabling units to connect over mountainous terrain or with a sea base far offshore. Satellite time on the Iridium constellation is free to operational units, said Michael Fallon, director for Marine Corps Programs at General Dynamics C4 Systems.

The Global Positioning System provides location information for all ETCS users in the net, allowing commanders to view where their units are on display screens.

The ETCS is designed to supplement current tactical satellite communications capability.

The developmental ETCS units were to have been evaluated this year during a planned experiment - Sea Viking 2004 - on the West Coast, a live experiment without using fixed radio relays, to evaluate the system in a beyond line-of-sight, "on the move" exercise from a sea base to an objective, said Vince Goulding, director of Sea Viking live experimentation at the Warfighting Lab. The deployment of the I Marine Expeditionary Force (T MEF) to Iraq in March forced the cancellation of the experiment, but the I MEF requested the ETCS be sent to Iraq for end-user evaluation.

Ten ETCSs and three Hammerhead personal computers were deployed to Iraq in August for field-level user evaluation with the I MEF, according to Lt. Col. Pincher Martin, ETCS project officer and a Royal Marine exchange officer with the Marine Corps Warfighting Lab.

A Warfighting Lab officer deployed to Iraq, Capt. Matt Simmons, is visiting numerous units and introducing the ETCS "all over the area" for testing and training, Goulding said. He noted that one specific ETCS test scenario was its use in command and control of vehicle convoy operations.

"We hope to deploy another 400 production systems in November to allow full MEF-wide concept evaluation," he said.

General Dynamics was awarded $100,000 for an initial task order study of ETCS, and has been provided approximately $3 million so far to develop the system, Fallon said. The ETCS has been installed in a vehicle-mounted version of the Unit Operations Center (OUC) - called the Combat Operations Center - for an evaluation by the Warfighting Lab.

Also built by General Dynamics C4 Systems, the UOC - designed to be set up on land in less than 40 minutes - is a scalable, portable commandand-control center that is established as a sea-based maneuver unit goes ashore. Shipped by Humvee-towed trailers that are air-transportable, the UOC is set up as an air-conditioned tent complex with laptop computer workstations, large-screen data displays and communications gear. The UOC is designed to provide a commander with full battlefield awareness and access to multiple-source information from command networks.