58-649: USS Cocopa (ATF-101) was an Abnaki -class fleet ocean tug that served on active duty with the U.S. Navy from 1944 to 1978, seeing action in World War II , the Korean War and the Vietnam War . After thirty-four years of service, she was sold to the Mexican Navy , where she was still in service as of 2009. Cocopa was named after an Arizona Indian tribe . She began her naval career with
116-426: A central point, or perhaps to a distributed system in which all participate, such that the information can be correlated and a location computed. Modern SIGINT systems, therefore, have substantial communications among intercept platforms. Even if some platforms are clandestine, there is still a broadcast of information telling them where and how to look for signals. A United States targeting system under development in
174-472: A confirmation, followed by observation of artillery fire, may identify an automated counterbattery fire system. A radio signal that triggers navigational beacons could be a radio landing aid for an airstrip or helicopter pad that is intended to be low-profile. Patterns do emerge. A radio signal with certain characteristics, originating from a fixed headquarters, may strongly suggest that a particular unit will soon move out of its regular base. The contents of
232-458: A different ECCM way to identify frequencies not being jammed or not in use. The earliest, and still common, means of direction finding is to use directional antennas as goniometers , so that a line can be drawn from the receiver through the position of the signal of interest. (See HF/DF .) Knowing the compass bearing, from a single point, to the transmitter does not locate it. Where the bearings from multiple points, using goniometry, are plotted on
290-640: A lower level, German cryptanalysis, direction finding, and traffic analysis were vital to Rommel's early successes in the Western Desert Campaign until British forces tightened their communications discipline and Australian raiders destroyed his principle SIGINT Company. The United States Department of Defense has defined the term "signals intelligence" as: Being a broad field, SIGINT has many sub-disciplines. The two main ones are communications intelligence (COMINT) and electronic intelligence (ELINT). A collection system has to know to look for
348-407: A map, the transmitter will be located at the point where the bearings intersect. This is the simplest case; a target may try to confuse listeners by having multiple transmitters, giving the same signal from different locations, switching on and off in a pattern known to their user but apparently random to the listener. Individual directional antennas have to be manually or automatically turned to find
406-648: A particular signal. "System", in this context, has several nuances. Targeting is the process of developing collection requirements : First, atmospheric conditions, sunspots , the target's transmission schedule and antenna characteristics, and other factors create uncertainty that a given signal intercept sensor will be able to "hear" the signal of interest, even with a geographically fixed target and an opponent making no attempt to evade interception. Basic countermeasures against interception include frequent changing of radio frequency , polarization , and other transmission characteristics. An intercept aircraft could not get off
464-515: A peace-time codebreaking agency should be created. The Government Code and Cypher School (GC&CS) was the first peace-time codebreaking agency, with a public function "to advise as to the security of codes and cyphers used by all Government departments and to assist in their provision", but also with a secret directive to "study the methods of cypher communications used by foreign powers". GC&CS officially formed on 1 November 1919, and produced its first decrypt on 19 October. By 1940, GC&CS
522-523: A precise picture of the normal operation of the High Seas Fleet , to infer from the routes they chose where defensive minefields had been placed and where it was safe for ships to operate. Whenever a change to the normal pattern was seen, it immediately signalled that some operation was about to take place, and a warning could be given. Detailed information about submarine movements was also available. The use of radio-receiving equipment to pinpoint
580-401: A radar is operating. Once the radar is known to be in the area, the next step is to find its location. If operators know the probable frequencies of transmissions of interest, they may use a set of receivers, preset to the frequencies of interest. These are the frequency (horizontal axis) versus power (vertical axis) produced at the transmitter, before any filtering of signals that do not add to
638-401: A safe distance from the user of the transmitter. When locations are known, usage patterns may emerge, from which inferences may be drawn. Traffic analysis is the discipline of drawing patterns from information flow among a set of senders and receivers, whether those senders and receivers are designated by location determined through direction finding , by addressee and sender identifications in
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#1732798296925696-404: A sensor is unique. MASINT then becomes more informative, as individual transmitters and antennas may have unique side lobes, unintentional radiation, pulse timing, etc. Network build-up , or analysis of emitters (communication transmitters) in a target region over a sufficient period of time, enables creation of the communications flows of a battlefield. COMINT ( com munications int elligence)
754-570: A small islet at the harbor's mouth. During the Korean War, USS Cocopa received one battle star for her service. After the war, Cocopa conducted numerous Pacific Ocean and Alaskan cruises. Her home port was changed from Pearl Harbor to San Diego in 1961. In March 1954, Cocopa was one of the ships tasked to support Operation Castle , a series of high-energy (high-yield) nuclear tests by Joint Task Force SEVEN (JTF-7) at Bikini Atoll . Official reports indicated that crewmembers suffered
812-426: A tactical SIGINT requirement, whereas the larger aircraft tend to be assigned strategic/national missions. Before the detailed process of targeting begins, someone has to decide there is a value in collecting information about something. While it would be possible to direct signals intelligence collection at a major sports event, the systems would capture a great deal of noise, news signals, and perhaps announcements in
870-478: A tank battalion or tank-heavy task force. Another set of transmitters might identify the logistic net for that same unit. An inventory of ELINT sources might identify the medium - and long-range counter-artillery radars in a given area. Signals intelligence units will identify changes in the EOB, which might indicate enemy unit movement, changes in command relationships, and increases or decreases in capability. Using
928-411: A vehicle. If these are regular reports over a period of time, they might reveal a patrol pattern. Direction-finding and radio frequency MASINT could help confirm that the traffic is not deception. The EOB buildup process is divided as following: Separation of the intercepted spectrum and the signals intercepted from each sensor must take place in an extremely small period of time, in order to separate
986-578: Is Amplitude comparison . An alternative to tunable directional antennas or large omnidirectional arrays such as the Wullenweber is to measure the time of arrival of the signal at multiple points, using GPS or a similar method to have precise time synchronization. Receivers can be on ground stations, ships, aircraft, or satellites, giving great flexibility. A more accurate approach is Interferometer. Modern anti-radiation missiles can home in on and attack transmitters; military antennas are rarely
1044-417: Is a sub-category of signals intelligence that engages in dealing with messages or voice information derived from the interception of foreign communications. COMINT is commonly referred to as SIGINT, which can cause confusion when talking about the broader intelligence disciplines. The US Joint Chiefs of Staff defines it as "Technical information and intelligence derived from foreign communications by other than
1102-415: Is acquired by a given country. Knowledge of physics and electronic engineering further narrows the problem of what types of equipment might be in use. An intelligence aircraft flying well outside the borders of another country will listen for long-range search radars, not short-range fire control radars that would be used by a mobile air defense. Soldiers scouting the front lines of another army know that
1160-543: Is in the general area of the signal. The owner of the transmitter can assume someone is listening, so might set up tank radios in an area where he wants the other side to believe he has actual tanks. As part of Operation Quicksilver , part of the deception plan for the invasion of Europe at the Battle of Normandy , radio transmissions simulated the headquarters and subordinate units of the fictitious First United States Army Group (FUSAG), commanded by George S. Patton , to make
1218-511: Is usually encrypted , signals intelligence may necessarily involve cryptanalysis (to decipher the messages). Traffic analysis —the study of who is signaling to whom and in what quantity—is also used to integrate information, and it may complement cryptanalysis. Electronic interceptions appeared as early as 1900, during the Boer War of 1899–1902. The British Royal Navy had installed wireless sets produced by Marconi on board their ships in
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#17327982969251276-510: The Admiralty ; Room 40 . An interception service known as 'Y' service , together with the post office and Marconi stations, grew rapidly to the point where the British could intercept almost all official German messages. The German fleet was in the habit each day of wirelessing the exact position of each ship and giving regular position reports when at sea. It was possible to build up
1334-527: The Battle of Jutland as the British fleet was sent out to intercept them. The direction-finding capability allowed for the tracking and location of German ships, submarines, and Zeppelins . The system was so successful that by the end of the war, over 80 million words, comprising the totality of German wireless transmission over the course of the war, had been intercepted by the operators of the Y-stations and decrypted. However, its most astonishing success
1392-716: The Russian Army ’s advance early in World War I and led to their disastrous defeat by the Germans under Ludendorff and Hindenburg at the Battle of Tannenberg . In 1918, French intercept personnel captured a message written in the new ADFGVX cipher , which was cryptanalyzed by Georges Painvin . This gave the Allies advance warning of the German 1918 Spring Offensive . The British in particular, built up great expertise in
1450-575: The Atlantic fleet during the waning months of World War II, making two passages across the Atlantic with barges in tow, followed by a third passage to Trinidad . Her second convoy was attacked by a German U-boat , with Cocopa barely escaping destruction. Cocopa was next ordered to the Pacific theater , witnessing the final days of the war between July and August of that year. V-J day found
1508-548: The COMINT gathering method enables the intelligence officer to produce an electronic order of battle by traffic analysis and content analysis among several enemy units. For example, if the following messages were intercepted: This sequence shows that there are two units in the battlefield, unit 1 is mobile, while unit 2 is in a higher hierarchical level, perhaps a command post. One can also understand that unit 1 moved from one point to another which are distant from each 20 minutes with
1566-438: The German defense think that the main invasion was to come at another location. In like manner, fake radio transmissions from Japanese aircraft carriers, before the Battle of Pearl Harbor , were made from Japanese local waters, while the attacking ships moved under strict radio silence. Traffic analysis need not focus on human communications. For example, a sequence of a radar signal, followed by an exchange of targeting data and
1624-474: The Korean War during the summer of 1953. During this period she served off both Korean coasts; in one operation, she towed HMCS Huron , a Royal Canadian Navy destroyer that had run aground on the island of Pang Yang-Do, just off the North Korean coast well north of enemy-held Wonsan harbor. At the time of the armistice, she went to Wonsan to aid in the removal of a Marine garrison occupying
1682-599: The Russian fleet prepared for conflict with Japan in 1904, the British ship HMS Diana stationed in the Suez Canal intercepted Russian naval wireless signals being sent out for the mobilization of the fleet, for the first time in history. Over the course of the First World War , a new method of signals intelligence reached maturity. Russia’s failure to properly protect its communications fatally compromised
1740-598: The Security Assistance Program, where she was recommissioned in the Mexican Navy as ARM Seri (RE-03) . As of 2009 the ship remains on active duty with that force. Abnaki-class tug The Abnaki -class tug is a class of United States Navy fleet ocean tugs which began construction in November 1942. Comprising 22 oceangoing tugboats , the class was constructed in response to
1798-453: The actual information is at 800 kHz and 1.2 MHz. Real-world transmitters and receivers usually are directional. In the figure to the left, assume that each display is connected to a spectrum analyzer connected to a directional antenna aimed in the indicated direction. Spread-spectrum communications is an electronic counter-countermeasures (ECCM) technique to defeat looking for particular frequencies. Spectrum analysis can be used in
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1856-506: The broader organizational order of battle . EOB covers both COMINT and ELINT. The Defense Intelligence Agency maintains an EOB by location. The Joint Spectrum Center (JSC) of the Defense Information Systems Agency supplements this location database with five more technical databases: For example, several voice transmitters might be identified as the command net (i.e., top commander and direct reports) in
1914-614: The capitulation of Captain Katsusaburo Usui and nineteen other Japanese soldiers who had been living on the island of Anatahan , in the Northern Mariana Islands since 12 June 1944. The ship repatriated these men and their personal effects to Guam , from whence they were ultimately returned to Tokyo , Japan on 6 July 1951. However, other Japanese holdouts continued to surrender over the next few decades, though in much smaller numbers. Cocopa saw action in
1972-446: The decision to target is made, the various interception points need to cooperate, since resources are limited. Knowing what interception equipment to use becomes easier when a target country buys its radars and radios from known manufacturers, or is given them as military aid . National intelligence services keep libraries of devices manufactured by their own country and others, and then use a variety of techniques to learn what equipment
2030-469: The different signals to different transmitters in the battlefield. The complexity of the separation process depends on the complexity of the transmission methods (e.g., hopping or time-division multiple access (TDMA)). By gathering and clustering data from each sensor, the measurements of the direction of signals can be optimized and get much more accurate than the basic measurements of a standard direction finding sensor. By calculating larger samples of
2088-512: The fronts, that we won the war!" Supreme Allied Commander, Dwight D. Eisenhower , at the end of the war, described Ultra as having been "decisive" to Allied victory. Official historian of British Intelligence in World War II Sir Harry Hinsley argued that Ultra shortened the war "by not less than two years and probably by four years"; and that, in the absence of Ultra, it is uncertain how the war would have ended. At
2146-420: The ground if it had to carry antennas and receivers for every possible frequency and signal type to deal with such countermeasures. Second, locating the transmitter's position is usually part of SIGINT. Triangulation and more sophisticated radio location techniques, such as time of arrival methods, require multiple receiving points at different locations. These receivers send location-relevant information to
2204-581: The highest doses (2.2 rem ) of radiation endured by any of the navy ships present at this operation. During the Vietnam War, Cocopa saw service in five campaigns: Advisory (1963), Vietnam Defense (1965), Counteroffensive Phase II (1967), Summer-Fall 1969 , and Ceasefire (1972). In 1965, Cocopa hosted Detachment Charlie of Beach Jumpers Unit One, Team Twelve, operating as the "Yankee Station Special Surveillance Unit". This outfit consisted of one officer and five enlisted men , whose mission
2262-448: The information being transmitted. Received energy on a particular frequency may start a recorder, and alert a human to listen to the signals if they are intelligible (i.e., COMINT). If the frequency is not known, the operators may look for power on primary or sideband frequencies using a spectrum analyzer . Information from the spectrum analyzer is then used to tune receivers to signals of interest. For example, in this simplified spectrum,
2320-541: The late 1890s, and the British Army used some limited wireless signalling. The Boers captured some wireless sets and used them to make vital transmissions. Since the British were the only people transmitting at the time, the British did not need special interpretation of the signals that they were. The birth of signals intelligence in a modern sense dates from the Russo-Japanese War of 1904–1905. As
2378-541: The late 1990s, PSTS, constantly sends out information that helps the interceptors properly aim their antennas and tune their receivers. Larger intercept aircraft, such as the EP-3 or RC-135 , have the on-board capability to do some target analysis and planning, but others, such as the RC-12 GUARDRAIL , are completely under ground direction. GUARDRAIL aircraft are fairly small and usually work in units of three to cover
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2436-574: The location of any single transmitter was also developed during the war. Captain H.J. Round , working for Marconi , began carrying out experiments with direction-finding radio equipment for the army in France in 1915. By May 1915, the Admiralty was able to track German submarines crossing the North Sea. Some of these stations also acted as 'Y' stations to collect German messages, but a new section
2494-564: The message need not be known to infer the movement. There is an art as well as science of traffic analysis. Expert analysts develop a sense for what is real and what is deceptive. Harry Kidder , for example, was one of the star cryptanalysts of World War II, a star hidden behind the secret curtain of SIGINT. Generating an electronic order of battle (EOB) requires identifying SIGINT emitters in an area of interest, determining their geographic location or range of mobility, characterizing their signals, and, where possible, determining their role in
2552-410: The message, or even MASINT techniques for "fingerprinting" transmitters or operators. Message content other than the sender and receiver is not necessary to do traffic analysis, although more information can be helpful. For example, if a certain type of radio is known to be used only by tank units, even if the position is not precisely determined by direction finding, it may be assumed that a tank unit
2610-588: The needs of World War II , but members of the class served in the Korean War and Vietnam War as well. The United States Navy no longer has any ships of this class in active duty. Electronic intelligence Signals intelligence ( SIGINT ) is the act and field of intelligence-gathering by interception of signals , whether communications between people ( communications intelligence —abbreviated to COMINT ) or from electronic signals not directly used in communication ( electronic intelligence —abbreviated to ELINT ). As classified and sensitive information
2668-492: The newly emerging field of signals intelligence and codebreaking (synonymous with cryptanalysis). On the declaration of war, Britain cut all German undersea cables. This forced the Germans to communicate exclusively via either (A) a telegraph line that connected through the British network and thus could be tapped; or (B) through radio which the British could then intercept. Rear Admiral Henry Oliver appointed Sir Alfred Ewing to establish an interception and decryption service at
2726-461: The other side will be using radios that must be portable and not have huge antennas. Even if a signal is human communications (e.g., a radio), the intelligence collection specialists have to know it exists. If the targeting function described above learns that a country has a radar that operates in a certain frequency range, the first step is to use a sensitive receiver, with one or more antennas that listen in every direction, to find an area where such
2784-417: The sensor's output data in near real-time, together with historical information of signals, better results are achieved. Data fusion correlates data samples from different frequencies from the same sensor, "same" being confirmed by direction finding or radiofrequency MASINT. If an emitter is mobile, direction finding, other than discovering a repetitive pattern of movement, is of limited value in determining if
2842-698: The ship in Leyte , Philippines. Following World War II, Cocopa shuttled between the Philippines, Shanghai , Okinawa and Hong Kong on occupation duty, before returning to Puget Sound Naval Shipyard in January 1947 for an overhaul. From 1948–49 she plied Alaskan waters. 30 June 1951, having returned to the Far East, Cocopa accepted what many writers have termed the last Japanese surrender from World War II. Lieutenant Commander James B. Johnson accepted
2900-509: The signal direction, which may be too slow when the signal is of short duration. One alternative is the Wullenweber array technique. In this method, several concentric rings of antenna elements simultaneously receive the signal, so that the best bearing will ideally be clearly on a single antenna or a small set. Wullenweber arrays for high-frequency signals are enormous, referred to as "elephant cages" by their users. A more advance approach
2958-451: The stadium. If, however, an anti-terrorist organization believed that a small group would be trying to coordinate their efforts using short-range unlicensed radios at the event, SIGINT targeting of radios of that type would be reasonable. Targeting would not know where in the stadium the radios might be located or the exact frequency they are using; those are the functions of subsequent steps such as signal detection and direction finding. Once
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#17327982969253016-509: The story of Operation SALAM , László Almásy 's mission across the desert behind Allied lines in 1942. Prior to the Normandy landings on D-Day in June 1944, the Allies knew the locations of all but two of Germany's fifty-eight Western Front divisions. Winston Churchill was reported to have told King George VI : "It is thanks to the secret weapon of General Menzies , put into use on all
3074-562: The whole of the British forces in World War II came under the code name " Ultra ", managed from Government Code and Cypher School at Bletchley Park . Properly used, the German Enigma and Lorenz ciphers should have been virtually unbreakable, but flaws in German cryptographic procedures, and poor discipline among the personnel carrying them out, created vulnerabilities which made Bletchley's attacks feasible. Bletchley's work
3132-595: Was created within Room 40 to plot the positions of ships from the directional reports. Room 40 played an important role in several naval engagements during the war, notably in detecting major German sorties into the North Sea . The battle of Dogger Bank was won in no small part due to the intercepts that allowed the Navy to position its ships in the right place. It played a vital role in subsequent naval clashes, including at
3190-630: Was essential to defeating the U-boats in the Battle of the Atlantic , and to the British naval victories in the Battle of Cape Matapan and the Battle of North Cape . In 1941, Ultra exerted a powerful effect on the North African desert campaign against German forces under General Erwin Rommel . General Sir Claude Auchinleck wrote that were it not for Ultra, "Rommel would have certainly got through to Cairo". Ultra decrypts featured prominently in
3248-712: Was in decrypting the Zimmermann Telegram , a telegram from the German Foreign Office sent via Washington to its ambassador Heinrich von Eckardt in Mexico. With the importance of interception and decryption firmly established by the wartime experience, countries established permanent agencies dedicated to this task in the interwar period. In 1919, the British Cabinet's Secret Service Committee, chaired by Lord Curzon , recommended that
3306-525: Was to jam Soviet electronic intelligence trawlers monitoring U.S. operations in the Gulf of Tonkin . Team members utilized random wave jamming with noises (including bagpipe recordings) to counteract Russian SIGINT activities. Cocopa also assisted in towing, recovery and similar operations throughout her tours in Vietnam. On 30 September 1978, Cocopa was decommissioned and sold to Mexico under
3364-680: Was working on the diplomatic codes and ciphers of 26 countries, tackling over 150 diplomatic cryptosystems. The US Cipher Bureau was established in 1919 and achieved some success at the Washington Naval Conference in 1921, through cryptanalysis by Herbert Yardley . Secretary of War Henry L. Stimson closed the US Cipher Bureau in 1929 with the words "Gentlemen do not read each other's mail." The use of SIGINT had even greater implications during World War II . The combined effort of intercepts and cryptanalysis for
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