Remember the scene in Patriot Games where the protagonist and his CIA colleagues watch real-time infrared images of helicopter-borne special ops warriors neutralizing terrorists in a remote Libyan desert? That might have been the stuff of Hollywood then, but it's reality now.

Thanks to Salt Lake City-based L-3 Communications' Tactical Common Data Link (TCDL), commanders in the field, on ships or in offices thousands of miles away can monitor streaming live surveillance video, allowing them to focus on a firefight, potential target or anything else on the ground.

These and other imaging capabilities are especially important in Afghanistan, where enemy compounds are often surrounded by high walls, and where the country's mountains and deep valleys make situational awareness an even tougher job for ground forces.

Initially independent of plans for the TDCL, the Navy decided to modernize its Lockheed Martin P-3 Orion aircraft with an Anti-Surface Warfare Improvement Program (AIP), a key component of network-centric warfare.

The modernization involves installing high-resolution, synthetic-aperture radar and electro-optic and infrared sensors to dramatically increase the ability to see over land. AIP has become the platform of choice to provide intelligence, surveillance and reconnaissance for land- and sea-based operational commanders in the Afghan conflict.

Although TCDL is not currently part of the defined AIP, TCDL units have been placed as prototypes on AIP aircraft; and their tests have been so successful that TCDL is now a candidate for AIP, said Captain George Hill, program manager for Naval Air Systems Command's Maritime Patrol Aircraft Program (PMA-290).

"TCDL allows us to send a wide variety of data off the aircraft at a high data rate," said Hill. "Perhaps the most tactically significant capability is that of sending streaming video from the electro-optic or infrared sensors on the airplane to a ground station which is within line of sight."

Though underground Taliban and Al Qaeda fighters are invisible to the naked eye, TDCL-equipped P-3s, thousands of feet in the air, can detect them and deliver ordnance, if necessary.

The newly installed TCDL has many advantages. From the secure-voice portion of the link, surface commanders can request visual verification of objects of interest as the planes pass over them. With the file transfer capability, digital images and files can be sent and received at air or ground stations. American and allied troops on the ground in contact with a TCDL-equipped P-3 can respond to that information almost immediately. The "sensor-to-shooter time" - the time from the moment a target is located to the moment it can be fired at - has been reduced from hours to minutes.

"The P-3C Orion with AIP will play a key role in ensuring battlespace dominance in the littorals of the 21st century," Vice Admiral John B. Nathman, commander of Naval Air Forces, told the Senate Armed Services Committee. "At any given time we have squadrons deployed in every major region of the world. From the Caribbean to Keflavik, from Signonella to Bahrain and Masirah in the Gulf, from the middle of the Indian Ocean on the island of Diego Garcia to Japan, our P-3s are providing critical surveillance, anti-surface warfare and undersea warfare to our unified CINCs [commanders in chief]."

New eyes and ears for an old workhorse

At one point during the last decade, the P-3 aircraft looked as if it was nearing the end of its operational life. But instead of replacing one type with another, the Navy embarked on an ambitious upgrade of the old workhorse.

The upgrade set a new baseline for configuring advanced sensors and weapons, increasing interoperability, replacing outdated components and reducing support costs where possible. Information remained as important as ever, but digital technologies had opened up many more possibilities.

Because it had been designed for submarine and coastal surveillance applications, the P-3 had always been replete with data-gathering reconnaissance equipment. However, the problem was distributing that information to terminals on the ground or at sea. Obsolete technologies had always hampered that task.

With obvious room for improvement in the area and a wide array of technologies at their disposal, the P-3 community began to think about a new way to share critical information: digital data links.

To incorporate this new technology into the existing P-3 fleet, the Navy went to L-3 Communications, provider of communications, telemetry and avionics systems to U.S. military and intelligence agencies, as well as to commercial telecommunications companies.

In 1998, L-3's prototype data link was installed on a single P-3 and the command ship USS Coronado as part of Fleet Battle Experiment (FBE)-Charlie.

Though the capability of the data link was limited to a single video feed, the experimental P-3 was nonetheless able to communicate information from a variety of special video cameras on the aircraft back to the ship-based surface terminal. Based on the success of those early FBE-Charlie tests, Navy researchers were encouraged to continue the voyage.

Later that year, the Defense Advanced Research Projects Agency (DARPA) funded the development of a low-cost, commercial off-the-shelf-based, open-architecture common digital data link (CDL).

Thus began the evolution of TCDL.

The TCDL airborne system is specifically designed for unmanned aerial vehicles (UAVs) in manned, nonfighter environments. The data rates, modulation techniques and transmission frequencies are fully interoperable with CDL systems.

Seeing the possibilities of this system, the Navy again approached L-3 Communications and convinced it to expand TCDL use beyond the P-3 platform to the S-3B Surveillance System Upgrade (SSU) aircraft.

Christened RTSDL (Real-Time Sensor Data Link), this expanded data link system added features to the TCDL baseline, including a second video channel, bi-directional Ethernet file transfer, two-way voice communications, improved electromagnetic interference protection and increased range.

It is a full-duplex Ku (subfrequency) band link with a 200-Kbps command link and a 10.71-Mbps return link. RTSDL utilizes the 10.16-Mbps downlink channel (Guardrail frame format) and local area networks onboard the aircraft and in the ground-based systems.

In April 1999, before L-3 Communications delivered the CDL-compatible RTSDL system, the company conducted a qualifying flight on the Predator unmanned aerial vehicle (UAV). This CDL system was capable of transmitting one encrypted video signal at a rate of 10.71 Mbps, a marked improvement over the first generation.

Video feed to multiple locations

FBE-Echo in 1999 became the flight test for the RTSDL. The same P-3 used in FBE-Charlie was outfitted with RTSDL.

A modified version of the shipboard system terminal used in FBE-Charlie was again installed on the USS Coronado. This time, however, the RTSDL video feed was connected to the ship's closed-circuit television network, making it possible for any person onboard to see what was being transmitted from the air above.

A standard TCDL surface terminal was also set up at a third location - at the littoral surveillance system/tactical exploitation system compound on the Camp Pendleton Marine Corps Base, CA.

The data link proved capable of sending video from the plane simultaneously to two different locations.

With the additional voice capability over the data link, commanders on the ship and land communicated directly to the camera operators in the air to request "eyes-on-target" information for specific images.

The file transfer capability of this system was bi-directional, allowing digital files to be transferred from air to ground or from ground to air. Most important, FBE-Charlie showed that it was possible to send two different video sources (e.g., color camera video, forward-looking infrared video, radar video) to ship- and land-based systems simultaneously in near-real-time.

Once more, the digital data link had delivered the promised results; the few problems with logistical support and training were not unusual for such prototype trials.

Consequently, a report delivered at a Pentagon debriefing on April 27, 1999, stated, "The RTSDL has demonstrated a quantum leap in P-3 connectivity with afloat and ashore commanders."

By January 2000, the S-3B SSU aircraft had been configured with RTSDL, providing enhanced connectivity with the carrier USS Abraham Lincoln and other large-deck ships for Commander, Cruiser Destroyer Group Three's COMPTU-EX exercise.

Like all carriers, the USS Abraham Lincoln is equipped with the CDL-compatible common high-bandwidth data link-surface terminal (CHBDL-ST). CHBDL served as the surface terminal for RTSDL on the Lincoln, with the terminal's companion Video Interface Unit distributing video from the aircraft to television sets throughout the ship.

This test was no less successful than its predecessors. The S-3B SSU aircraft successfully downlinked live video, voice and image files to the Lincoln. Before the aircraft's 2000 deployment on the Lincoln, a summary brief of its testing stated, "S-3B SSU has demonstrated network-centric, real-time connectivity with afloat and ashore commanders via RTSDL/CHBDL."

Like the P-3 and Coronado before it, the S-3B SSU and Lincoln were able to dramatically outpace past benchmarks for effective communication. The SSU deployment on the Lincoln was so successful that, at the conclusion of the six-month cruise, the SSU was rapidly redeployed to the USS Enterprise for another six-month deployment, ending in November 2001.

Based on the success of the P-3 and S-3B exploitation of RTSDL data, the PMA290 AIP P-3 Program Office purchased additional RTSDL systems.

The Navy then contracted with L-3 Communications in June 2000 to make improvements to its RTSDL system, and this new generation was designated the Tactical Common Data Link-Navy (TCDL-N). This system added a rugged conduction-cooled chassis, a 16-channel acoustic interface, a full TCP/IP-Ethernet interface, an increased data rate of 45 Mbps, and came at a reduced size, weight and power consumption - as well as offering improved operating range with same-size surface antennas.

This new system was delivered to the Navy in June 2002 and was to be installed on a P-3 and undergo flight tests in August of the same year.

The system's programmable modem offers several waveforms and data rates that can be selected during flight. Replacing the radio frequency converter and antenna can easily change the Ku band operating frequency. The antenna itself can be changed from omni-directional to directional for broadcast or directed transmissions. Options include bulk encryption and programmable uplink or downlink data rates.

The TCDL ground data terminal accommodates a variety of tactical field situations, enabling two people to set it up in a half-hour. The design includes a 400-meter fiber-optic cable between the radiating antenna/modem assemblies and the Link Interface Unit. An omni-directional antenna is also provided for close-in operations. The nominal uplink data rate of 200 Kbps includes direct-sequence, spread-spectrum modulation.

An integral part of network-centric warfare

Though the P-3 has historically been used as an antisubmarine craft, in recent years it has seen duty in other fields. The U.S. Customs Service, for example, uses the plane to assist in intercepting narcotics smuggling. Most important, the P-3 has become an integral part of Operation Enduring Freedom, something that the TCDL system helped make possible.

Adding the TCDL data link capability to Navy assets has provided ship-based and land-based commanders eyes-on-target information at distances and speeds previously unheard of - enabling  air, surface and ground forces to significantly shorten the time needed to accurately put ordnance on target. Current TCDL systems have also been connected to the Secret Internet Protocol Router Network (SIPRNET) for secure network transfer of digital information. In short, the P-3 has been updated for the Internet age.

The demand for P-3 aircraft equipped with the TCDL and other AIP systems will continue to rise. During the ongoing fiscal year 2003 budget reviews by both the House and Senate Armed Services Committees, the P-3 community has received the funding necessary to further improve its ability to support the United States in future military conflicts. As a result, and thanks to the successful implementation of TCDL, P-3 Orion's star isn't likely to set on military service anytime soon.