[[File:Joint Tactical Information Distribution System Users, 1990.jpg|thumb|320px|Joint Tactical Information Distribution System Users, 1990]]
The '''Joint Tactical Information Distribution System (JTIDS)''' is/was an [[L band#IEEE L band|L band]] Distributed Time divisionDivision multipleMultiple access|Access (DTDMA) network radio system used by the [[United States armed forces]] and their allies to support [[data communication]]s needs, principally in the air and missile defense community. It providesproduces a spread spectrum,high-[[Radiosignal 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|jam]]-resistance, high-speedand interception. In Time Division Multiple Access (TDMA) (supposedly like cell phone systems), [[cryptography|cryptoeach time interval (e.g. 1 second) is divided into time slots (e.g. 1024 per second). Together, all the time slots in the interval are called a "frame". Each slot is "bursted" (transmitted) at a different frequency (FSK). Within each slot, the phase angle of the transmission burst can be varied to provide PSK. Each type of data to be transmitted is assigned a slot or block of slots (channel). In TDMA, the slot frequencies remain fixed from second to second (frame to frame). In DTDMA, the slot frequencies and/or slot assignments for each channel do not remain fixed from frame to frame but are varied in a pseudo-secure]]random manner. The slot assignments, frequencies, and information may all be encrypted to provide computer-to-computer connectivity in support of every type of military platform from [[U.S. Air Force|Air Force]] [[Fighter aircraft|fighters]] to [[United States Navy|Navy]] [[submarine]]s.
The full development of JTIDS commenced in 1981 when a contract was placed with Singer-Kearfott (later GEC-Marconi Electronic Systems, now [[BAE Systems Electronics and Integrated Solutions|BAE Systems E&IS]]). Fielding proceeded slowly throughout the late 1980s and early 1990s with rapid expansion (following [[9-11|9/11]]) in preparation for Operation Enduring Freedom (Afghanistan) and Operation Iraqi Freedom. Development is now carried out by [[Data Link Solutions LLC|Data Link Solutions]], a joint BAE/[[Rockwell Collins]] company.
