Signals intelligence operational platforms are employed by nations to collect signals intelligence, which is intelligence-gathering by interception of signals, whether between people (i.e., COMINT or communications intelligence) or between machines (i.e., ELINT or electronic intelligence), or mixtures of the two. As sensitive information is often encrypted, signals intelligence often involves the use of cryptanalysis. However, traffic analysis—the study of who is signalling whom and in what quantity—can often produce valuable information, even when the messages themselves cannot be decrypted.

Ground platforms It can be difficult to draw the line between a ground-based SIGINT receiving station, and facilities that have control, coordination, and processing functions in the "bigger picture" of signals intelligence. 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 signals intelligence platforms were listening stations on the ground. Early tactical stations were in use as early as World War I, but permanent strategic signals intelligence 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 be safe, 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 antennas are used. If the parabolic antennas 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)."

Australia: ground platforms The current (2019) Joint Military Communications Ground Station (JMCGS) is a SIGnals INTelligence intercept facility located at Kojarena appx 15 Mi east north east of Geraldton, Western Australia. The facility has been built in the early 1990s and originally manned by AUS defence personnel, later augmented by UK personnel previously assigned to Hong Kong. In 2007 the AUS and US authorities approved a Memorandum Of Understanding (MOU) stipulating the expansion and future rules of cooperation for the JMCGS. The new facility, becoming ops in 2010, is equipped with 4 large 25m radomes covering dish antennas intended to monitor and intercept voice and metadata SATellite COMmunications. The other antennas, a 15m radome and seven uncovered smaller dishes, are intended for the fully automated US naval Mobile User Objective System, a new 'next generation' narrowband networked satellite constellation for Ultra-High-Frequency satellite communications enabling secure all-weather and all-terrain 3 and 4G mobile telecommunications. The JMCGS is controlled by the Australian Signals Directorate (ASD) and is being operated under the UKUSA agreement meaning that all data obtained is being shared with the NSA.

The Joint Defence Facility Pine Gap (JDFPG) a.k.a. Pine Gap facility is located approximately 12 Mi west south west of Alice Springs, Northern Territory. JDFPG has been established in 1966, originally as a satellite relay station becoming operational in 1970 as US-Australian NAVDET Combined Support Group with approximately 100 AUS and US military personnel. In 1989 the unit was renamed Joint Defense Space Research Facility, Pine Gap, in 1998 becoming US Naval Security Group Detachment, Alice Springs and in 2005 becoming Navy Information Operations Detachment (NIOD) Alice Springs, Australia. Currently (2019) NIOD Alice Springs strength is approximately 700 AUS and US military and it is operating as an Echelon IV station subordinate to NIOC Maryland (CTF 1060). The JDFPG is currently equipped with six large radomes and 13 small radomes and uncovered dishes intended for military and civilian SATCOM, cellphone and internet voice and metadata interception. JDFPG is also being controlled by the Australian Signals Directorate (ASD) and is being operated under the UKUSA agreement.

Former press and media statements that the facility is being operated by the CIA have never been confirmed; there is no proof of US civilian presence at JDFPG.

The Joint Defence Facility Nurrungar (JDFN), located approximately 9 Mi south of Woomera, South Australia, was a ground station operated by the Australian Department of Defence and the USAF. Its official mission was space-based surveillance, in particular early warning for ICBM launches and nuclear detonations using US Defense Support Program satellites in geostationary orbits. Nurrungar derives from an aboriginal term meaning "listen". JDFN has been operational from 1969 through to its closure in 1999.

The Department of Defence Receiving Station Shoal Bay is located approximately 12 Mi north east of Darwin, Northern Territory. Shoal Bay is being controlled and operated by the Australian Signals Directorate (ASD) and its mission is SATCOM interception as well as interception of high frequency signals. It has a staff of 85 military and civilian personnel and is currently (2019) equipped with 14 dish antennas.

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. Of the additional bases are in Cuba, two of which are operated by China: 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. A 'cyber-warfare' unit at the station focuses on computer data traffic. The second is located northeast of Santiago de Cuba at the easternmost 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 antennas, seven of them directed at Atlantic satellites, is clearly as extensive and capable as sites in the UKUSA network. 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 Guiana 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). 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 of Kommando Cyber- und Informationsraum of the Bundeswehr, in Gelsdorf, which is responsible for controlling Germany's SAR Lupe and its replacement, the SARah, system and analysing the retrieved data. A large data archive of images will be kept in a former Cold War bunker. Its data is shared with the Bundesnachrichtendienst BND.

Germany: tactical ground platforms Germany operates several tactical ground platforms for SIGINT gathering. Bad Aibling: ex US Army SIGINT now BND Satcom and cellular monitoring Bramstedtlund: BND directionfinder Butzbach: BND directionfinder Gablingen: ex US Army SIGINT now BND directionfinder Hof: ex US Army SIGINT now BND Satcom intercept Langen: ex USAF Rhein/Main site now BND cellular monitoring Rheinhausen: BND Satcom intercept Schöningen: BND Satcom intercept Stadum: Bundeswehr HF-SIGINT intercept Übersee: BND directionfinder

India: ground platforms

India: strategic ground platforms India is known to operate a strategic signals intelligence platform developed as part of "Programme Divya Drishti" by the Defence Electronics Research Laboratory of DRDO. The system is operated by the Indian Army.

India: tactical ground platforms The primary platform for tactical signals intelligence in the Indian Army is based on the Samyukta Electronic Warfare System developed by the Defence Electronics Research Laboratory of DRDO.

In addition to Samyukta, other role-specific tactical platforms include: Himashakti, a signals intelligence platform for operations in mountainous terrain to support constrained logistics and mobility challenges. Himraj, a Ground Based Mobile ELINT System (GBMES) of the Indian Air Force that operates in the wide frequency range covering both communication and Radar bands.

New Zealand: ground platforms During the Second World War, New Zealand established seven radio interception stations to support the Anglo-American war effort against Japan. These seven stations and their Wellington intelligence headquarters were linked to the Allied analysis centres in Australia. In 1949, the Royal New Zealand Navy established a permanent radio-receiving station called NR1 (Navy Receiver 1), which was located south of Waiouru. NR1 was situated beside the Navy's main radio receiving Station, NR2. NR1 operated for thirty-three years until being closed down in 1982. On February 15, 1955, the New Zealand Combined Signals Organization (NZCSO) was established to collect signals intelligence and to operate the NR1 station. Between 1955 and 1974, New Zealand signal officers were also regularly posted to a secret interception station in Singapore which was jointly run by Britain and Australia. According to the peace researcher and journalist Nicky Hager, this station was used to support British and later American military operations in Southeast Asia.