Downlink sensors include, but are not limited to, Electro-Optical (EO), Infrared (IR), and Synthetic Aperture Radar (SAR) images and signals intelligence, supporting all U.S. defense services, North Atlantic Treaty Organization (NATO) partners, and other select allies. Its purpose is to securely connect multiple airborne and space intelligence collection platforms with surface users, such as tactical ground commands, surface ships, low-flying aircraft crews, and other military command and control (C2) staff. CDL narrowband uplink controls Intelligence, Surveillance, and Reconnaissance (ISR) platforms and payloads. The implementation of CDL is about the transmission of unprocessed sensor data and control data to enable the U.S. defense “eyes in the sky.” The technology is a secure way to provide military decision-makers on the ground with the detailed, accurate visual situational awareness that can make or break the success of either a short-term immediate mission or the long-term activities of a broader mission.

How does Common Data Link work?

The Common Data Link standard secures transmission of data and imagery, and all parties transferring sensitive intelligence imagery are required to use it where possible. The part of the frequency spectrum where CDL generally operates is not reserved for restricted use and is shared with other systems. Standard CDL primarily operates in the Ku radio band – most commonly used for both defense and commercial satellite communications – but generally at faster data transfer rates than commercial signals, ranging from 200 Kilobits Per Second (Kbps) to 274 Megabits Per Second (Mbps). The faster the transfer rate, the more quickly intelligence and orders can be passed on and implemented in the field to enhance mission success. This is at the expense of the use of directional apertures and higher power consumption. Plans are underway for an upcoming CDL protocol to support 1096 Mbps or more. The ongoing acceleration of transfer speeds may require advanced modulations, higher power outputs and expanding the use of other bands, but the DoD and its technology partners are careful to not “strand” legacy systems in the process.

While the CDL program sets specification standards, assuring its maximum performance also requires advanced Common Data Link hardware components – terminals, Radio Frequency Front-End (RFFE) interfaces, and antennas with the modular versatility to fit, integrate, and perform seamlessly across a wide range of manned and unmanned air, marine, space, ground, and personal-carry platforms. These systems also need to be upgradable, both to operate with legacy CDL systems and to flex up to next generation specifications as they are introduced. As electronics have become smaller and lighter, yet more capable at greater distances, CDL developers have been able to significantly increase both their performance and adaptability to evolving platforms, even as their use in transferring a wider variety of media has become more and more important. This evolutionary upgradability will vary from one application to another, but most will include:

  • Embedded AES-128/256 transmission security (TRANSEC)
  • Type 1 cryptographic & TEMPEST security
  • High-speed encryption, multiplexing, encoding, transmission, demultiplexing, and routing
  • Greater integration of Commercial-Off-The-Shelf (COTS) equipment into military systems
  • Adding the wider range of data rates and modulations of newer Bandwidth Efficient CDL (BECDL) systems
  • Development of new integrated circuits on advanced materials, doing more with less size, weight, and power
  • New waveform development that takes advantage of recent signal transmission, intercept, and detection features
  • Improved satellite network high-speed connectivity

Are Tactical Common Data Links different from the Common Data Link?

The term Tactical Common Data Link simply means a Common Data Link technology that has been custom-developed for a particular tactical purpose. The original Tactical Common Data Link (TCDL) was developed by the U.S. DoD for the specific tactical purpose of mounting cameras and sensors that meet CDL standards on unmanned air vehicles – also known as UAVs or drones – to gather visual intelligence from the air in conflict zones. When that development began, most CDL systems were much too large, expensive and heavy to mount on UAVs, on many helicopters, or even to use on small ground-based vehicles. Subsequent miniaturization and power system breakthroughs in circuit designs, cameras, antennas, and networks have resulted in much smaller, lighter, and yet significantly more capable CDL devices and systems. In fact, because it was developed well after CDL was introduced, TCDL can actually transmit more types of information – still images, video, radar, and other sensor information – while maintaining the same secure protocols. As a result, a number of similar systems have been in development for other specific tactical CDL uses, including a Navy Tactical Common Data Link (NTCDL), Network Tactical Common Data Link (NWTCDL), Multi-Platform Tactical Common Data Link (MP-TCDL), Multi-Role Tactical Common Data Link (MR-TCDL), and others.

Related topics to explore

Army Common Data Link • Common Cryptographic Module (CCM) • Common Data Link Executive Agent • Common Data Link Interface Module • Common Data Link Layer Protocol • Common Data Link Program • Common Data Link Radio System • Department of Defense Joint Spectrum Center (JSC) • Fixed-Satellite Service (FSS) system • Joint Interoperability Certified (JITC) • Joint Interoperability Test Command • Multi-Platform Common Data Link • Radar Common Data Link • Real-time ISR CDL Applications • Space CDL • U.S. Defense Information Systems Agency (DISA)


This information page is provided as a service to our readers by BAE Systems, Inc., a U.S.-based world leader in aerospace, defense, power, and intelligence solutions. Learn more about us here.

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