The Joint Tactical Information Distribution System (JTIDS) is an L band Distributed Time Division Multiple Access (DTDMA) network radio system used by the United States armed forces and their allies to support data communications needs, principally in the air and missile defense community. It produces a spread spectrum signal using Frequency-shift keying (FSK) and Phase-shift keying (PSK) to spread the radiated power over a wider spectrum (range of frequencies) than normal radio transmissions. This reduces susceptibility to noise, jamming, and interception. In JTIDS Time Division Multiple Access (TDMA) (similar to cell phone technology), each time interval (e.g., 1 second) is divided into time slots (e.g. 128 per second). Together, all 1536 time slots in a 12-second interval are called a "frame". Each time slot is "bursted" (transmitted) at several different carrier frequencies sequentially. Within each slot, the phase angle of the transmission burst is varied to provide PSK. Each type of data to be transmitted is assigned a slot or block of slots (channel) to manage information exchanges among user participation groups. In traditional TDMA, the slot frequencies remain fixed from second to second (frame to frame). In JTIDS TDMA, the slot frequencies and/or slot assignments for each channel do not remain fixed from frame to frame but are varied in a pseudo-random manner. The slot assignments, frequencies, and information are all encrypted to provide computer-to-computer connectivity in support of every type of military platform to include Air Force fighters and Navy submarines.
The full development of JTIDS commenced in 1981 when a contract was placed with Singer-Kearfott (later GEC-Marconi Electronic Systems, now BAE Systems E&IS). Fielding proceeded slowly throughout the late 1980s and early 1990s with rapid expansion (following 9/11) in preparation for Operation Enduring Freedom (Afghanistan) and Operation Iraqi Freedom. Development is now carried out by Data Link Solutions, a joint BAE/Rockwell Collins company, ViaSat, and the MIDS International consortium.
About
JTIDS is one of the family of radio equipment implementing what is called Link 16. Link 16, a highly-survivable radio communications design to meet the most stringent requirements of modern combat, provides reliable Situational Awareness (SA) for fast-moving forces. Link 16 equipment has proven, in detailed field demonstrations as well as in the AWACS and JSTARS deployment in Desert Storm, the capability of basic Link 16 to exchange user data at 115 kbit/s, error-correction-coded. (Compare this to typical tactical systems at 16 kbit/s, which also have to accommodate overheads in excess of 50% to supply the same transmission reliability.)
While principally a data network, Link 16 radios can provide high quality voice channels and navigation services as accurate as any in the inventory. Every Link 16 user can identify itself to other similarly equipped platforms at ranges well beyond what Mark XII Identification Friend or Foe (IFF) systems can provide. Additionally, Link 16-equipped platforms capable of identification through other means (such as radar and TENCAP Blue Force Tracking) can pass that "indirect" identification data as part of its SA exchange. The capabilities of Link 16 are best represented by the JTIDS or its follow-on Multifunctional Information Distribution System (MIDS) terminals. The TADIL-J message format forms the basis for the mandates in the DoD Tactical Data Link Management Plan.
There are benefits to the full-scale implementation of the two key elements of Link-16: (1) the message "catalog" and (2) the specific radio waveform (i.e., frequency hopped, Lx-band CPSM, spread-spectrum and Reed–Solomon coding, omni-directional broadcast). Link 16 terminals implement the "NI" node-to-node protocols as well as one or more of the ICD-compliant user interfaces.