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FAS Project on Intelligence Reform

Tactical Common Data Link [TCDL]

The Defense Airborne Reconnaissance Office (DARO) and the Defense Advanced Research Projects Agency (DARPA) are planning the execution of a technology and demonstration program leading to a Tactical Common Data Link (TCDL). The goal of the TCDL acquisition is to develop a family of CDL-compatible, low-cost, light weight, digital data links with the capability to support a wide range of Intelligence, Surveillance and Recognizance (ISR) applications. The initial TCDL design will be targeted for unmanned aerial vehicle UAV applications (e.g., Predator and Outrider). In the future TCDL design is expected to be extended to additional manned and unmanned applications (e.g., Guardrail, Rivet Joint, Reef Point, ARL and Joint STARs (JSTARs) ). The TCDL will operate in Ku band and will be interoperable with the existing CDL at the 200 Kbps forward link and 10.71 Mbps return link data rates and is expected to interface to the Tactical Control System (TCS). In addition the TCDL is expected to be capable of operation in other frequency bands and operate with variable forward and return link data rates.

TCDL will provide near-real-time connectivity and interoperability between multiple TCDL collection platforms, TCDL surface terminals, and currently fielded Common Data Link (CDL) interoperable systems operated by the armed services and Government agencies. The CDL radio terminal currently being produced by Loral Comm Systems, Salt Lake City, Utah is an operational system flying worldwide with excellent performance. Its cost and weight, however, preclude its use on Predator and Outrider. In addition, Outrider does not require the full range of features provided by CDL. In addition to providing interoperability among CDL equipment elements, CDL provides backward compatibility with the widely deployed Interoperable Data Link (IDL) family of systems.

It is the desire of DARO to develop a digital LOS communications architecture for the Outrider and Predator UAVs and the Tactical Control System (TCS) that is CDL interoperable, is scalable for other platforms, and is modular in construction so that, as new sensors and users are introduced, the system architecture can accommodate them without a complete restructuring of the data link.

The TCDL architecture is expected to employ as much commercial off-the-shelf (COTS) hardware as practical and is expected to utilize an open systems architecture. The level of modularity, utilization of COTS, and application open systems is to be developed and specified by the contractor.

The TCDL communications system provides a full-duplex, digital transmission between intelligence collection platforms and surface terminals by means of point-to-point or LOS transmissions. It is intended that the TCDL airborne terminal receive a spread spectrum command link. The command link rate will be at the CDL 200 Kbps data rate with the capability of embedding the Predator UAV command link rate of 64 Kbps. In addition, the airborne terminal will transmit the CDL low-rate 10.71 Mbps return link rate that can be received LOS by a TCDL surface terminal, a CDL surface terminal, or a Remote Video Terminal (RVT).

The TCDL return link must be designed to operate in the 14.40 to 14.83 GHz band, and the forward link must operate in the 15.15 to 15.35 GHz band. The TCDL is required to be tunable in 5 MHz step sizes or less. The TCDL design goal for LOS slant range is 200 km at 15,000 feet above ground level (AGL); however the TCDL is required to operate at a slant range of 150 km AGL. The requirement is to maintain connectivity between the airborne terminal and the surface terminal during normal aircraft operations, except during outages due to air-frame blockage.

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http://www.fas.org/irp/program/disseminate/tcdl.htm
Maintained by Steven Aftergood
Created by John Pike
Updated Saturday, June 21, 1997 11:14:49 AM