View source for Naval Tactical Data System

[[Image:NTDS-CIC-mockup-training.jpg|right|thumbnail|320px|NTDS training in a mock-up of a shipboard [[Combat Information Center|CIC]]]]
'''Naval Tactical Data System''' ('''NTDS''') was a computerized information processing system developed by the [[United States Navy]] in the 1950s and first deployed in the early 1960s for use in [[Surface warfare|combat ship]]s. It took reports from multiple sensors on different ships and collated it to produce a single unified map of the battlespace. This information could then be relayed back to the ships and to the [[weapons]] operators.

== Reason for development ==

===Background===
[[Warships]] have compartments known as [[Combat Information Center]]s, or CICs, that collect, sort and then communicate all of the battlefield information known to that ship. Information about targets would be forwarded to the CIC by the operators of the [[radar]] and [[sonar]] systems, where crewmen would use this information to update a shared map. Commanders used the map to direct weapons to particular targets. The system was similar to the [[Battle of Britain Bunker]] system, but on a smaller scale.

There were two major problems with this system. One was that each ship had its own view of the battlespace, independent of the rest of the ships in the task force. This led to force allocation problems - the ship with the right weapon for a particular target might not see that target on their sensors, or two ships might attempt to attack the same target while ignoring another. This could be addressed by adding inter-ship radio or flag signals as another input to the map, but the workload of moving so many bits of data was enormous. This led to the second major problem, the high inherent manpower requirements and lack of shipboard space.

During [[World War II]] and the immediate post-war era, major navies started studying these problems in depth, as concerns about coordinated attacks by long-range high-speed aircraft became a serious threat. To give the task force enough reaction time to deal with these threats, "pickets" were posted at a distance from the force to allow their radars to pick up the targets while still on the approach. The information from these ships then had to be relayed, normally by voice, to the other ships in the force. Some experiments with video cameras pointed at the radar displays were tried, but were subject to transmission loss when the ships pitched on the swells and the high-bandwidth antennas no longer pointed at each other.<ref name=hill/>

What was ultimately desired was a system that could collect target information from any sensor in the fleet, use that to build a single shared picture of the battlespace, and then distribute that data accurately and automatically to all of the ships. As the data was now being collected almost entirely from electronic devices and displays, a system that picked up this data directly from those displays would be ideal.

===Previous systems===
{{Main|Comprehensive Display System}}
Devised to be used in conjunction with the [[Type 984 radar]], the first such system was developed by the [[Royal Navy]] in the immediate post-war era using analog systems that tracked the rate of motion of "blips" on radar screens. The operators used a joystick to align a pointer with the target and then pushed a button to update the location. The circuitry then adjusted the rate of predicted movement of the blip and displayed a pointer that moved over time. Updating no longer required any inputs, unless the predicted motion began to differ at which point additional button pushes could be used to update it. The data for each of these tracks, a series of voltages, could then be transmitted around the ship, and later, inter-ship transmission using [[pulse-code modulation]]. [[Ralph Benjamin]] found that decoding the position of the joystick was not ideal and desired a system that read out relative motion instead of absolute position, and invented the [[trackball]] as a solution.<ref name=hill>Peter Hill, [http://www.ieeeghn.org/wiki/index.php/Oral-History:Ralph_Benjamin "Oral-History:Ralph Benjamin"], IEEE History Center, 16 September 2005</ref> The Type 984 radar and Comprehensive Display System (CDS) were fitted to the aircraft carriers {{HMS|Eagle|R05|2}}, {{HMS|Hermes|R12|2}} and {{HMS|Victorious|R38|2}}

This work suffered from the reliability of the analog circuits used to run the system. By the early 1950s the digital computer appeared to offer a solution, not only by greatly increasing reliability through the removal of any moving parts, but also by directly working with the digital data that made up the plots. Data from one computer simply needed to be copied directly to another, there was no need to code and decode analog signals representing those values. The [[Royal Canadian Navy]] began work on such a system under their [[DATAR]] project, which included the first working example of the trackball concept. Unfortunately their design used tubes, and the resulting machine was so large it took up almost all of the free space on the {{Sclass|Bangor|minesweeper}} it was installed on. Efforts to build a transistorized version of the DATAR did not receive funding and the project ended.<ref>John Vardalas, "From DATAR To The FP-6000 Computer", IEEE Annals of the History of Computing, Volume 16, Number 2 (1994)</ref>

===System implementation===
The work by the RN and RCN teams was well known to the USN starting as early as 1946, and included live demonstrations of the Canadian system on [[Lake Ontario]]. They also built their own version of the Royal Navy's concept as the "Electronic Data System", and 20 sets were eventually produced by [[Motorola]]. In 1953 they produced a new system for air direction known as the "Intercept Tracking and Control Console" which could track two incoming and two outgoing (interceptor) formations. However, the system was huge and did not include inter-ship transmission, so was only used on a small number of [[aircraft carrier]]s.

However, all of these solutions had problems that limited their usefulness. Analog systems were difficult to keep operational and subject to errors when maintenance was less than perfect. The Canadian version, using digital computers, was better, but needed to be transistorized. The [[US Air Force]] was also involved in their own [[Project Charles]], a similar system but on a much larger scale. Their system also used vacuum tubes and would end up being the largest computers ever built, each occupying {{convert|20000|ft2}} of floor space, weighing {{convert|150|ST}}, and consuming 1.5 megawatts of electrical power. The Navy kept a watchful eye on these developments and others under Project Cosmos.<ref>{{Cite book |url=https://books.google.com/books?id=Mi8MhzheOokC&q=%22project+cosmos%22+navy&pg=PA68 |title=When computers went to sea |access-date=July 13, 2017 |author1=David L. Boslaugh |date=1999 |publisher=IEEE Computer Society Press |isbn=9780471472209 }}</ref>

Development of computers in the mid-1950s led both by the Navy's long interest in code-breaking computers, the introduction of newer types of transistors, and the widespread introduction of [[core memory]], reached a point where a Navy version of Air Force's [[Semi-Automatic Ground Environment|SAGE air defense network]] was a practical possibility. The Navy began development of the NTDS system using a transistorized digital computer in 1956. With NTDS and wireless data links, ships could share the information gathered by their sensors with other ships in a task force. In October 1961, NTDS was on the [[USS Oriskany (CV-34)|USS Oriskany]] carrier and the [[USS King (DDG-41)|USS King]] and [[USS Mahan (DDG-42)|USS Mahan]] destroyers as service test ships. First production NTDS runs were ordered for 17 high priority ships with missiles including 10 [[Belknap-class cruiser]]s under construction between 1962-67.<ref>[https://ethw.org/First-Hand:Moving_the_Firing_Key_to_NTDS_-_Chapter_6_of_the_Story_of_the_Naval_Tactical_Data_System First-Hand:Moving the Firing Key to NTDS - Chapter 6 of the Story of the Naval Tactical Data System]  [[Engineering and Technology History Wiki]]  Retrieved October 26, 2021</ref>  NTDS was the inspiration for the [[Aegis Combat System|Aegis]] system in the 1980s.<ref>[https://www.computerhistory.org/timeline/computers/ Timeline of Computer History] - [[Computer History Museum]]</ref>

== Hardware description ==
A variety of [[UNIVAC]] [[embedded system|embedded]] [[computer]]s, including the first fielded version of the late 1950s, the CP-642A<ref>[http://ed-thelen.org/comp-hist/univac-ntds.html CP-642A]</ref> ([[AN/USQ-20]]), typically with 30 [[bit]] words, 32K words of magnetic core or thin film [[memory]], 16 [[series and parallel circuits#Parallel circuits|parallel]] [[I/O]] [[communication channel|channel]]s (also 30 bits wide) connected to [[radars]] and other [[peripheral]]s, and a [[RISC]]-like instruction set, were used.  Logic circuits used discrete [[transistors]] and other elements [[solder]]ed to a printed [[circuit board]] with connectors running along one side.  Each card was coated in a [[varnish]]-like substance to prevent exposure to corrosion-inducing [[salt spray]] (See [[Conformal Coating]]). A number of cards were connected and secured to a tray on rollers.  In turn, several trays of various types, interconnected and secured to a metal enclosure, constituted the computer.  Most NTDS computers were [[water-cooled]], though some later lighter-weight models were [[air-cooled]].

== Modem description ==
The NTDS information was transmitted between ships of [[Carrier battle group|aircraft carrier battle groups]] using [[Rockwell Collins#History|Collins Radio's]] [[Arthur A. Collins#Telecommunication|Kineplex]] [[modem|modems]].  Kineplex was a parallel-tone, [[Orthogonal frequency-division multiplexing|multicarrier]] [[modem]].<ref>Boslaugh, David L., [https://ethw.org/First-Hand:Building_the_U.S._Navy's_First_Seagoing_Digital_System_-_Chapter_4_of_the_Story_of_the_Naval_Tactical_Data_System Ch. 4: Story of the NTDS] - Engineering and Technology History Wiki</ref><ref>[https://archive.org/details/TNM_Collins_data_transmission_system_Kineplex_20180116_0287 Collins Data Transmission System Kineplex] scanned Collins Radio product literature at Archive.org</ref>

== Seymour Cray and the NTDS ==

[[Seymour Cray]] is credited for developing the first NTDS processor, the [[AN/USQ-17]].  However, this design did not go into production.

==ASW Ships Command & Control System ==
ASW Ships Command & Control System (ASWSC&CS) was a NTDS system for [[antisubmarine warfare]] (ASW). It was implemented only on the [[frigate]]s {{USS|Voge|FF-1047|6}}, {{USS|Koelsch|FF-1049|6}} and the ASW aircraft carrier {{USS|Wasp|CVS-18|6}} in 1967. The ASWSC&CS allowed the development of improvements in antisubmarine warfare using digital computers, which were implemented in other ASW ship classes. [[UNIVAC]] was contracted to define the hardware and develop the software to incorporate ASW functions.<ref>[http://vipclubmn.org/sysnavy.html Navy Systems Chapter] - VIP Club: Information Technology (IT) Pioneers -  retirees from [[UNISYS]] and [[Lockheed Martin Maritime Systems and Sensors|Lockheed Martin MS2]]</ref>

AN/UYQ-100 Undersea Warfare Decision Support System (USW-DSS) is the current system fielded in 2010.<ref>[https://www.navy.mil/Resources/Fact-Files/Display-FactFiles/Article/2166791/anuyq-100-undersea-warfare-decision-support-system-usw-dss/ AN/UYQ-100 Undersea Warfare Decision Support System (USW-DSS)]. US Navy Fact File.  September 2021.</ref><ref>AN/UYQ-100 Undersea Warfare Decision Support System (USW-DSS). [https://media.defense.gov/2020/May/18/2002302043/1/-1/1/NPG17.PDF Navy Program Guide]. Department of the Navy.  2017.  page 143,</ref>

== See also ==
*Command and control centers:
** [[Air Defense Control Center]]
** [[Combat Information Center]]
** [[Mission Control Center]]
** [[National Emergency Command Post Afloat]]
*Computers:
** 30 & 32 bit computers used in the NTDS
*** [[AN/USQ-17]]
*** [[AN/USQ-20]]
*** [[AN/UYK-8]]
*** [[AN/UYK-7]]
*** [[AN/UYK-43]]
** 16 bit computers used in alternate and related roles
*** [[AN/UYK-20]]
*** [[AN/AYK-14]]
*** [[AN/UYK-44]]
* [[Arthur A. Collins#Telecommunication|Collins Radio's Kineplex Multicarrier Modem]]
* [[Advanced combat direction system]]
* [[H/ZKJ]]
* [[Marine Tactical Data System]]
* [[Ship Self-Defense System]]
* [[Joint Tactical Information Distribution System]]
* [[Tactical communications]]
* [[MIL-STD-1397]]
* [[Over-the-horizon radar]]
* [[CMS-2 (programming language)|CMS-2 programming language]]

==Notes==
{{reflist}}

== References ==
*David L. Boslaugh (1999). When Computers Went to Sea: The Digitization of the United States Navy. IEEE Computer Society Press. {{ISBN|0-7695-0024-2}}.

== External links ==
*[http://ed-thelen.org/comp-hist/univac-ntds.html UNIVAC-NTDS: UNIVAC 1206, AN/USQ-20] &ndash; From the Antique Computer website
*[http://www.uss-king.com/ntds.shtml USS King] {{Webarchive|url=https://web.archive.org/web/20180912204433/http://www.uss-king.com/ntds.shtml |date=2018-09-12 }}
*[http://vipclubmn.org/sysnavy.html Navy Systems Chapter] - VIP Club: Information Technology (IT) Pioneers -  retirees from [[UNISYS]] and [[Lockheed Martin Maritime Systems and Sensors|Lockheed Martin MS2]]
*[http://purl.umn.edu/40809 Engineering Research Associates (ERA)-Remington Rand-Sperry Rand Records, 1945-1988], [[Charles Babbage Institute]], University of Minnesota.  See series Jay A. Kershaw Records, 1955-1965 including day files and memoranda related to his work as peripherals manager on the Naval Tactical Data System (NTDS) at Sperry Univac.
*[https://ethw.org/First-Hand:No_Damned_Computer_is_Going_to_Tell_Me_What_to_DO_-_The_Story_of_the_Naval_Tactical_Data_System,_NTDS First-Hand:No Damned Computer is Going to Tell Me What to DO - The Story of the Naval Tactical Data System, NTDS] Table of Contents - Chapters 1 - 9, by David Boslaugh - An account of the development of the Naval Tactical Data System, the first digitized weapon system in the US Navy. With photographs, anecdotes and personal recollections of the events and technology, from [[Engineering and Technology History Wiki]].
*[http://www.ieeeghn.org/wiki/index.php/First-Hand:The_Anti-Submarine_Warfare_Ship_Command_and_Control_System_-_The_First_Spin_Off_from_the_Naval_Tactical_Data_System First-Hand:The Anti-Submarine Warfare Ship Command and Control System - The First Spin Off from the Naval Tactical Data System] from IEEE Global History Network.

{{Naval combat systems}}

[[Category:Anti-submarine warfare]]
[[Category:Computer systems of the United States Navy]]
[[Category:Military equipment introduced in the 1960s]]