Signals intelligence collection, ground-based

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SIGINT ground-based platforms variously directly receive electromagnetic signals of interest, and control, coordinate, and process in the "bigger picture" of SIGINT. Many stations, for the countries with stations in many parts of the world, do have both aspects. There are also some that are clearly intercept only.

The first SIGINT platforms were listening stations on the ground. Early tactical stations were in use as early as World War I, but permanent strategic SIGINT stations were established as world tensions grew before WWII.

Arguably, one combined intercept and jamming technique of WWI was the use of shotguns against carrier pigeons, followed by reading the message attached to the bird.

While pigeons can probably relax, other collection techniques may enjoy a resurgence. One specialized technique, originally used in the First World War but again in the Korean War, was interception using ground return from wired telephones. In mountainous terrain, it might again have applications, such as Afghan caves where wire might be run without the danger of free-space interception.

Satellite communications generally must be intercepted by large parabolic antennas on the ground, although there are possibilities that aircraft, intelligence satellites, and ships might also intercept. "To receive satellite signals, ...only parabolic antennae are used. If the parabolic antennae are standing on an open site, it is possible to calculate on the basis of their position, their elevation and their compass (azimuth) angle which satellite is being received. This is possible, for example, in Morwenstow (UK), Yakima (USA) or Sugar Grove (USA)." [1].

Australia: Ground Platforms

A facility at Geraldton, Australia, with Australian and British personnel was built in the 1990s.[1] The British personnel were previously assigned to Hong Kong,. It is reported to have four satellite antennae...trained on satellites above the Indian Ocean and the Pacific."According to statements made under oath in the Australian Parliament by an expert, transmissions from civilian telecommunications satellites are intercepted at Geraldton."

Another station, in Pine Gap, was established in 1966 and jointly operated by Australians and Americans. As opposed to many military-only bases, Pine Gap has a signinficant number of CIA as well as military NAVSECGRU staff. It has 18 antennae, and has been considered first a receiving station for SIGINT satellites, but the size of some of its antennae are more associated with a requirement to intercept communications from commercial communications satellites. The station in Pine Gap was established in 1966. It is run by the Australian Secret Service (DSD), and roughly half of the 900 station personnel are Americans from the CIA and "Until 1980 no Australians were allowed to work in the signals analysis department; since then, they have been granted free access to all parts of the station, with the exception of the Americans’ own cryptography room."

The European Parliament report stated that the Shoal Bay facility is "run solely by the Australian Intelligence Service. Of the satellite antennae visible on photographs, the five larger ones have a maximum diameter of 8 m, and the sixth antenna visible is smaller still. According to information provided by Richelson, the antennae are trained on the Indonesian PALAPA satellites. It is not clear whether the station is part of the global system for the interception of civilian communications."[1]

Cuba: Ground Platforms

While Cuba had traditionally been a Soviet client, it both has been developing indigenous capabilities, including equipment design and manufacture, as well as having Chinese-operated stations on its soil. Within the Cuban intelligence ministry, a Counter-Electronic Warfare Department was established in 1997, at the same level as the Technical Department and the Foreign Intelligence) Department. In 1992, a tactically oriented Counter-Electronic Warfare Department was created. The national intelligence organization also runs electronic warfare and SIGINT for the Air Force and Navy.

Russia and China, at various times, have operated or are operating intercept stations in Cuba. The largest and best-known, Lourdes SIGINT Station, was shut down by Russia in 2001, along with the Russian station at Cam Ranh Bay, Vietnam.[2] Of the additional bases are in Cuba, two of which are operated by China:[3]

  • Bejucal
  • Yaguajay
  • Santiago de Cuba
  • Paseo

Chinese personnel, in 1998, began operating the Bejucal and Santiago de Cuba facilities. The first seems concerned with intercepting US telephone communications and data traffic, while the second appears aimed at US military satellites One is a large complex at Bejucal, just south of Havana, which has ten SATCOM antennas, and which is primarily concerned with intercepting telephone communications in the US.[3] A 'cyber-warfare' unit at the station focuses on computer data traffic. The second is located northeast of Santiago de Cuba at the eastern-most part of the country and is 'dedicated mainly to intercepting U.S. military satellite communications'.

France: Ground Platforms

France: Strategic Ground Platforms

The technical department of the French espionage service, DGSE, operates a major communications satellite collection site at Domme, in the Dordogne valley to the east of Bordeaux, in south-western France. This site, which includes at least 11 collection antennae, seven of them directed at Atlantic satellites, is clearly as extensive and capable as the largest sites in the UKUSA network. [4] Reports by journalists, cited in the European Parliament report, confirm the Domme installation, and also a facility at Alluetts-le-Roi near Paris. There were also reports of stations in Kourou in French Guyana and in Mayotte.

France: Tactical Ground Platforms

At the tactical force protection levels, Thales was awarded a contract to build SAEC (Station d'Appui Electronique de Contact) force protection stations, by the French defence procurement agency (DGA)[5]. The contract was awarded in 2004 and initial operational capability is expected by 2007.

The SAEC is an armored vehicle carrying ELINT and the Thales XPLORER COMINT to complement EW platforms. It will have wideband acquisition, direction-finding and analysis sensors, for real-time monitoring and recording for subsequent analysis. It can operate standalone, or network using VHF (PR4G) and HF (TRC3700) communication systems for networking with other SAEC and the SGEA higher level EW system.

SGEA will do intelligence fusion, including from UAV-carried sensor, and coordinate with electronic attack.

Germany: Ground Platforms

Germany: Strategic Ground Platforms

Germany operates a strategic ground station at the Zentrum für Nachrichtenwesen der Bundeswehr (ZNBw), in Gelsdorf, which is responsible for controlling Germany's SAR Lupe system and analysing the retrieved data. A large data archive of images will be kept in a former Cold War bunker belonging to the ZNBw. The Bundesnachrichtendienst also operates several SIGINT platforms.

Germany: Tactical Ground Platforms

Germany operates several tactical ground platforms for SIGINT gathering.

The Kommando Strategische Aufklärung (Strategic Reconnaissance Command) of the Bundeswehr operates three mobile and three stationary SIGNIT battalions.

Russia: Ground Platforms

Russia: Strategic Ground Platforms

Russia closed its major ground collection stations at Lourdes in Cuba and Cam Ranh Bay in Vietnam. Stations remain at the Ras Karma Military Airbase, near QaDub on Socotra Island in Yemen, across the Red Sea to Somalia, and at the mouth of the Gulf of Aden. which lies opposite the coast of Somalia at the mouth of the Gulf of Aden in the Indian Ocean. An inactive station at Ramona in North Korea may reopen.[6]

Russia: Tactical Ground Platforms

Arbalet-M is mentioned in Russian literature as a portable direction-finding and electronic attack system [7] used in the Second Chechen War.

United Kingdom: Ground Platforms

United Kingdom Strategic Ground Platforms

Ayios Nikolaos Station on Cyprus is a British installation. The station, which has 14 satellite antennae whose size is unknown...[its] location, close to the Arab states, and the fact that Ayios Nikolaos is the only station sited within certain footprints (above all spot beams) in this area, point to its having an important role in intelligence gathering.

Morwenstow, England, operated by GCHQ, has "21 satellite antennae, three of which have a diameter of 30 m; ... the size and number of the satellite antennae and the location of the station, only 110 km from the [commercial] telecommunications station in Goonhilly, leave no doubt as to its task of intercepting transmissions from telecommunications satellites. [4]

United Kingdom Tactical Ground Platforms

The British 18 (UKSF) Signals Regiment provides SIGINT [8] personnel, including from the preexisting 264 (SAS) Signals Squadron and SBS Signals Squadron to provide specialist SIGINT, secure communications, and information technology augmentation to operational units. They may be operating in counterterror roles in Iraq in the joint UK/US TASK FORCE BLACK[9].

United States: Ground Platforms

Remember that national-level strategic sensors can support tactical units, and tactical units can send significant information to the national level.

United States: Strategic Ground Platforms

NSA, with NRO cooperation, operates a number of Regional SIGINT Operations Sites (RSOC) and other support activities[5].

  • Europe
  • Menwith Hill Station (Yorkshire, UK). (USMC Support Company G)
  • Bad Aibling (Munich, Germany)
  • Asia
  • Misawa Air Force Base, Japan (USMC Support Company E)
  • North America
  • Fort Gordon, Georgia. US Army facility (USMC Support Company D)
  • Kelly Air Force Base, San Antonio, Texas. US Air Intelligence Agency (USMC Support Company H)
  • At NSA Headquarters, Ft. Meade, MD,a company of the Marine Support Battalion

The Marine units report National SIGINT Operations Center at NSA headquarters at Ft. Meade, MD [10]. These facilities often have both a SIGINT receiving and a higher-level management and control function.

Jeffrey Richelson, for the George Washington University National Security Archive, links the Air Force's 544th Intelligence Group with ECHELON operations [11]. He places its Detachment 2 located at Sabana Seca, Puerto Rico; Detachment 3 at Sugar Grove, West Virginia; and Detachment 4 at Yakima, Washington.

In the 1994 Air Intelligence Agency (AIA) history, Misawa is specifically associated with ECHELON only in the context of a collection system called LADYLOVE. Misawa, although many of its SIGINT units were deactivated in 2000-2001, still had an RSOC coordination role. [12] The AIA history says the "Misawa LADYLOVE activity was initiated during the Cold War to intercept Soviet military communications transmitted via satellite—along with similar operations at Menwith Hill, UK; Bad Aibling, Germany; and Rosman, North Carolina."

According to Duncan Campbell, "In 1999, the Sabana Seca field station appeared to have at least four radomes for satellite communications, one located beside an existing high frequency interception system targeted on Cuban radio communications."[4] According to Richelson, this is the assignment of Detachment 2 of the 544th Intelligence Group.[11]

The Naval Security Group Activity (NAVSECGRUACT) at Sugar Grove, West Virginia, has missions defined including "maintaining and operating an ECHELON site"[13]. Detachment 3 of the US Air Force 544th Intelligence Group is a tenant at Sugar Grove, and the 544th has been associated with ECHELON activities. While the main subordinate command at Sugar Grove is redacted, it would appear, given the presence of large satellite antennas at Sugar Grove, but it not appearing in lists of NSOCs, that it is principally an intercept facility. [4] Campbell associates Sugar Grove with NSA programs called TIMBERLINE, LANFORD, LATERAL, and SALUTE.

The Yakima site, home of Detachment 4 of the 544th, is considered an ECHELON site:[1] "Six satellite antennae have been installed on the site [they are claimed to be] trained on INTELSAT satellites over the Pacific (two satellite antennae) and INTELSAT satellites over the Atlantic, and on INMARSAT Satellite 2.

"The fact that Yakima was established at the same time as the first generation of INTELSAT satellites went into orbit, and the general description of the tasks of the 544th Intelligence Group, suggest that the station has a role in global communications surveillance. A further clue is provided by Yakima’s proximity to a normal satellite receiving station, which lies 100 miles to the north."

United States: Tactical Ground Systems

Some systems are used at land stations of all services. TROJAN SPIRIT is a familly of mobile satellite communications (SATCOM) systems that uses commercial or military satellites to receive, transmit, and process secure, voice, data, video teleconferencing (VTC), and facsimile communications. Initially, it used the [AN-AN/]]TSQ-190(V) ground equipment, which had various incremental upgrades, to TROJAN SPIRIT II and then TROJAN SPIRIT LITE.

It provides 14 channels of digital voice or data, to intelligence (SCI) or general military (GENSER) with a maximum aggregate data rate of 1.544 megabits per second (Mbit/s). LAN communications are supported by SCI and GENSER ethernets. Routers provide access to the SIPRNET, JWICS, NSA networks, and the defense SATCOM system, as needed for coordinating MAGTF SIGINT and other intelligence operations. The system fits into 3 HMMWVs with mounted standard integrated command post lightweight multipurpose shelters, tunnel-mounted power generation units, and towed 2.4 meter (C, Ku-bad) and 6.1 meter (C, Ku, X-band) antennas.

TROJAN SPIRIT II is being replaced by AN/TSQ-226(V)TROJAN SPIRIT LITE. The TROJAN SPIRIT LITE is fielded in four versions:

  • (V)1 -a commercial off-the-shelf version in a transit case configuration used to augment Military Intelligence dissemination and communications requirements primarily at corps and division, and some EAC
  • (V)2) for the Marines
  • (V)2-SBCT (pallet, shelter, ECV, trailer) for Army Brigade Combat Teams
  • (V)3 is similar to (V)2 but adds an additional shelter and workstation.
  • (V)4 for Echelons above Corps

Both TROJAN SPIRIT II and TROJAN SPIRIT LITE will transition to the Warfighter Information Network-Terrestrial (WIN-T).

US Army: Tactical Ground Stations

While some may call "Restructuring of the United States Army" a "buzzword", the idea reflects some very major changes. Among the most basic is moving away from the division as the fundamental unit of action, and moving to smaller and more flexible brigade combat teams {BCT). As a very basic part of those changes, not only are considerably more intelligence assets being assigned to the BCTs, but to larger army formations. In both these cases, SIGINT represents a very major portion of the growth in assets[14]. Each combat BCT has an organic military intelligence (MI) company, with improved SIGINT capability. In addition, five battlefield surveillance brigades (BfSB), of which an MI Collection Battalion is the core element, are being formed. Each of those battalions is 1/3 SIGINT; the Army expects to have more than 7,000 new MI soldiers by 2013.

Prophet Block I began rolling out in 1999-2000, and was operational in Afghanistan. It replaced the AN/TSQ-138 Trailblazer, AN/TRQ-32 Teammate, AN/TLQ-17A Trafficjam, and the AN/PRD-12 systems.[15]. The system will be getting incremental improvements, which reflect both improvements in technology and in military organizational structure [16]. At the time of initial operational capability, the assumption was that PROPHET would be issued six systems per division, four per armored cavalry regiment (ACR), three per Brigade Combat Team (IBCT). Tasking for Prophet will come from primarily from the division-level Analysis and Control Element, modified by brigade-specific priorities and then send them to the Prophet via SINCGARS radio.

Physically, the basic Prophet platform is built around a mounted AN/PRD-13(V)2 direction-finding (DF) system designed to provide force protection in a DS role to the maneuver brigade. This system operates in the HF, VHF and UHF spectra. It provides line-of-bearing (LOB) data and intercept on unencrypted, single-channel push-to-talk transmissions.

It can be put into subassemblies that can be carried by a four-man team individual soldiers, althout the more common deployment will be in an M1097 HMMWV. In the vehicle-mounted variant, it can operate while moving; there are racks for two AN/VRC-92 vehicle-mounted SINCGARS Combat Net Radios with backpacks, and carries an antenna mast and other equipment.

Tactical communications, not just for SIGINT, are "flattening", such that units do not just report up their chain of command, but to adjacent units. One of the rationales for doing so is that a combat unit can see an opportunity and move against it, without it being misidentified by a neighboring unit and being engaged with "friendly fire."

Prophet Block II adds electronic attack (EA) capability to Prophet, while Block III upgrades the Prophet receiver to collect advanced signals. These enhancements will be coordinated with UAVs and tactical aircraft with expanded SIGINT capability. Blocks IV (expected IOC 2008) and V (expected IOC 2015) [17] add MASINT along with micro-and robotic receivers to the Prophet Ground system.

MASINT will include ground surveillance radars (PPSSD) and the Improved-Remotely Monitored Battlefield Sensor System (I-REMBASS) aboard a shelter-mounted HMMWV. Prophet, with the I-REMBASS monitoring system, will form the Ground Sensor Platoon of the brigade combat team reconnaissance, surveillance, and target acquisition (RSTA) Squadron.

Prophet Air will begin in a UAV.

I-REMBASS is planned to be replaced by Unattended Ground Sensors of the Future Combat Systems.

US special operations ground equipment

For SIGINT operations, the basic US Marine augmentation to Force Recon is a 6-man detachment from a Radio Reconnaissance Platoon. There is a SIGINT platoon within the Intelligence Company of the new Marine Special Operations Support Group [18].

Intended for the Radio Reconnaissance Teams attached to Marine Expeditionary Units, the radio reconnaissance equipment program (RREP) SIGINT suite (SS)-1 is a semiautomated, integrated, open architecture radio intercept and DF system composed of a ruggedized computer and six functional modules that plug together. RREP SS-1 modules may operate independently or semi-independently . SS-1 enables the radio reconnaissance teams (RRTs) to target the majority of low-level, single-channel, unencrypted tactical signals of interest used by military, police, insurgents, and other potential hostile forces throughout the world.

The RREP SS-2 will provide a highly deployable, man-transportable, signals intercept and DF system employed by RRTs in support of the entire spectrum of MAGTF operations. RREP SS-2 employs advanced receiver capabilities, cellular phone and other digital communications collection and DF technology, global positioning system map navigation software, a more modular design, and electronic attack capabilities. As with RREP SS-1, the SS-2 operates at the modular level and at the integrated system level. The system can be controlled manually or via subcompact personal computer.

The handheld integrated directional receiver and homing (HIDRAH) system is a man-transportable, tactical, cordless, radio intercept and signal line-of-bearing (LOB) DF system consisting of several COTS items in an enclosure appropriate for the field. HIDRAH provides RRTs with a threat I&W capability during radio reconnaissance foot-mobile patrols and signal homing support for tactical recovery of aircraft and personnel operations. The HIDRAH system has a unique design that may be employed independently in a handheld manner or by mounting it to an M16 rifle.

Army Special Forces have the Support Operations Team-Alpha that can operate with an SF team, or independently. This is a low-level collection team, which typically has four personnel [19]. Their primary equipment is the AN/PRD-13 SOF SIGINT Manpack System (SSMS), with capabilities including direction-finding capability from 2 MHz to 2 GHz, and monitoring from 1 to 1400 MHz [20].

US Marine Corps: Tactical Ground Stations

Subordinate to Radio Battalions, US Marines have a multifunction AN/MLQ-36 Mobile Electronic Warfare Support System that gives the operators limited armor protection. It contains

  • Two WJ-8618B(S1) acquisition receivers and a WJ-32850 MANTIS DF system which, together, provide signal intercept and radio direction finding
  • One AN/ULQ-19(V) electronic attack set
  • a secure communications system,
  • an intercom system installed
  • logistics variant of the light armored vehicle (LAV)-25

The AN/PRD-12 is a tactical, man-transportable system that provides search, intercept, and DF on communications signals in the HF/VHF/UHF bands. Up to four PRD-12 stations can be networked, providing DF data to a mission control station via radio link with single-channel ground and airborne radio system (SINCGARS) equipment. Any of the four stations can act as mission control. [10]

Assigned 1 per Marine Division, 1 per Marinew Air Wing, and one per Radio Battalion, the AN/MSC-63A is a shelterized communications switch that provides a secure semiautomated data communications switch and terminals for the processing of general service (GENSER) or defense special security communications system (DSSCS) sensitive compartmented information (SCI) record message traffic.[10]

The AN/TSQ-130(V)2/(V)5 technical control and analysis center (TCAC) is a tactical, transportable, SIGINT-processing, analysis and reporting system installed in a large, self-contained, modified S-280G shelter. TCAC is the primary system used by the Radio Battalion SIGINT support unit. The (V)2 is the baseline system, while the (V)5 has upgraded communications capabilities. It is to be replaced by the AN/MYQ-8 TCAC-PIP will replace the TCAC.

AN/MYQ-8 will consist of three remotely operable analysis workstations (RAWSs), one communications interface module (CIM), and one supervisor control module (SCM). Remoteable Analysis Workstations (RAWS) provides the capability to do analysis and reporting in or away from the shelter, connecting via LAN or radio in the latter case. It also can operate in a stand-alone mode. Communications Interface Modules (CIM) provide man-machine interface between the TCAC PIP and other RadBn systems (e.g., team portable collection system, mobile electronic warfare support system) or external intelligence agencies. The Supervisor Control Module (SCM) is an administrator interface to file server and system supervision of the TCAC.[10]

The AN/USC-55 commander’s tactical terminal (CTT) is a multiservice-developed, special application, UHF satellite communications receiver that can be dedicated to receive critical, timesensitive intelligence by commanders and intelligence centers at all echelons, in near-real-time, at GENSER or SCI levels. The receiver provides one full-duplex and two receive-only channels.

The team portable collection system (TPCS) upgrade is a semiautomated, man-transportable communications intelligence (COMINT) system. It provides intercept, collection, radio direction finding, analysis, reporting, and collection management support. The TPCS upgrade made up of three subsystems:

  • COMINT collection subsystem (CCS), including the AN/PRD-12 direction finding set (to be replace by TOPMAKER) and collection receivers
  • analysis subsystem (AS)
  • communications subsystem (CS) using single-channel radio nets are used to link TPCS upgrade outstations with the RadBn TCAC to allow automated processing and dissemination of collected information and ultimate dissemination to the MAGTF G-2/S-2 and other organizations.

US Army and Marines: Tactical Ground Stations and Unmanned Aerial Vehicles

An improved version of the AN/MLQ-36, used by the Army and Marines, is a multifunction, open-architecture AN/MLQ-36A Mobile Electronic Warfare Support System Product Improvement Program, which is a total replacement of the electronics in the AN/MLQ-36.[10] The MEWSS PIP provides the ability to detect and evaluate enemy communications emissions, detect and categorize enemy noncommunications emissions (i.e., battlefield radars), determine Lines-of-Bearing (LOBs), and degrade enemy tactical radio communications during amphibious assaults and subsequent operations ashore. When mission configured, and working cooperatively with other MEWSS PIP platforms, the common suite of equipment can also provide precision location of battlefield emitters. The system is designed to have an automated tasking and reporting data link to other MAGTF assets such as the AN/TSQ-130 Technical Control and Analysis Center (TCAC) PIP. The MEWSS PIP and future enhancements will provide the capability to exploit new and sophisticated enemy electronic emissions and conduct Electronic Attack (EA) in support of existing and planned national, theater, Fleet, and MAGTF SIGINT/EW operations [21].

The MQ-8 unmanned helicopter's capabiltities includes Corps-level signals intelligence for rhe U.S. Army and Marines. At Brigade level, this comes from the MQ-7 Hunter/MQ-1C Sky Warrior, and the RQ-11 at battalion. [22]


  1. 1.0 1.1 1.2 1.3 European Parliament Report on ECHELON, 2001. Retrieved on 2006-08-14
  2. Cable News Network, Russia to close Cuban spy station. Retrieved on 2007-10-13
  3. 3.0 3.1 Information Warfare (IW): Signals Intelligence (SIGINT), Electronic Warfare (EW) and Cyber-Warfare. Asia and Cuba, February 2003
  4. 4.0 4.1 4.2 4.3 Campbell, Duncan, Interception Capabilities 2000: Report to the European Parliament
  5. 5.0 5.1 Thales (27 November 2006), Tactical SIGINT stations for force protection. Retrieved on 2007-10-18 Cite error: Invalid <ref> tag; name "Loring2007" defined multiple times with different content
  6. Shcherbakov, Aleksey (March 22,1999), Major Loss of Intelligence Gathering Capability
  7. Thomas, Timothy L., Information Warfare in the Second (1999-Present) Chechen War: Motivator for Military Reform?, US Army Foreign Military Studies Office. Retrieved on 2007-11-14
  8. 18 (UKSF) Signals Regiment. Retrieved on 2007-11-16
  9. TASK FORCE BLACK. Retrieved on 2007-11-16
  10. 10.0 10.1 10.2 10.3 10.4 US Marine Corps (22 February 1999), Marine Corps Warfighting Publication (MCWP) 2-15.2, Signals Intelligence, US Marine Corps. Retrieved on 2007-10-11
  11. 11.0 11.1 Richelson, Jeffrey T. (January 13, 2000), National Security Archive Electronic Briefing Book No. 24: The National Security Agency Declassified. Retrieved on 2007-10-11
  12. US Air Force (15June1995), History of the Air Intelligence Agency, 1 January - 31 December 1994. Retrieved on 2007-10-11
  13. Commander, Naval Security Group (September 3, 1991), NAVSECGRU Instruction C5450.48A, Subj: Mission, Functions and Tasks of Naval Security Group Activity (NAVSECGRUACT) Sugar Grove, West Virginia,. Retrieved on 2007-10-11
  14. Association of the US Army (July 2007), Key Issues Relevant to Army Intelligence Transformation. Retrieved on 2007-10-14
  15. AN/MLQ-40(V)3 Prophet. Retrieved on 2007-11-13
  16. Kevin C. Peterson (July, 2000), "Prophet: Tactical SIGINT for the 21st Century - ground signal intelligence system", Military Intelligence Professional Bulletin. Retrieved on 2007-11-13
  17. Lawlor, Maryann (October 2002), "Signal Intelligence System Uncovers Enemy Sites", Signal. Retrieved on 2007-11-13
  18. U.S. Marine Corps Forces, Special Operations Command(MARSOC). Retrieved on 2007-11-17
  19. FM 3-05.102 Army Special Forces Intelligence, 2001-07
  20. L3/Linkabit Communications, The AN/PRD-13 (V1) Man Portable Signal Intelligence System
  21. US Marine Corps (22 February 1999), Marine Corps Warfighting Publication (MCWP) MCWP 3-40.5 Electronic Warfare, US Marine Corps. Retrieved on 2007-10-13
  22. Field Manual 3-36, Electronic Warfare in Operations, U.S. Army, February 2009,p. E-13