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Electronic Warfare EW, encompasses, in all battle phases, military actions involving the use of EM energy to determine, exploit, reduce or prevent hostile use of EM spectrum and the actions, which retain friendly use of the EM spectrum. EW consists of three related sectors, viz., Electronic Protection (EP), Electronic Attack (EA), and Electronic Support (ES).
ES sensors allow the passive detection of emissions from radar systems and can be used to classify and geo-locate radar systems operated by an adversary. ES is responsible for supplying intelligence and threat recognition that are necessary for EA and EP to function effectively. In the context of radar, ES consists of two divisions: Electronic Intelligence (ELINT), and Electronic Support Measures (ESM).
Signal Intelligence (SIGINT) involves interception of signals broadcasted by communication systems, radars, and other electronic systems. On the basis of the type of signal intercepted, SIGINT is divided into three subcategories Electronic Intelligence (ELINT); Communication Intelligence (COMINT); and Foreign Instrumentation Signals Intelligence (FISINT)
According to the foreign press, the SIGINT system may first have been used for support of combat operations during the Arab-Israeli war of 1974 for monitoring the air defense radars, staff and command posts of the Arab countries, and also for intercepting radio communications, including conversations of Arab pilots in the air.
Conventional SIGINT systems include ground stations, combat aircraft carrying specialized SIGINT equipment, unmanned aerial vehicles, dedicated SIGINT aircraft, and AEWCS. There are many disadvantages of these systems. Ground-based SIGINT system has a very limited visibility as SIGINT requires line-of-sight to the emitter. Manned SIGINT aircraft are very expensive and prone to missile attacks. Losing even one AEWCS represents a huge blow – financial and strategic. Area of operation is limited. The UAV based SIGINT is prone to both missile and jamming attacks. Violation of airspace strains diplomatic relations.
SIGINT satellites can be deployed in various orbits depending on the type of signals the satellite is designed for, e.g. To detect low power radar signals, the satellite has to be placed in low-earth orbit while high power early warning radars can be analyzed using a satellite stationed in geostationary earth orbit. The operational orbit of the satellite can be optimized to achieve optimum dwell time over a specific area. Another important factor determining the orbit of a SIGINT satellite is the size of the antenna and the sensitivity of receiving equipment. Space based communications intelligence assets may be placed in low Earth orbit (LEO -below 2000 km) or in geosynchronous orbit (GEO). Each has its advantages and disadvantages.
LEO COMINT satellites are required to monitor low power transmissions that have short range and/or antenna beam patterns that confine most of the signal to the horizontal plane. LEO satellites may approach as close as 300 km above a transmitter of interest and within about 1000 km in the horizontal beam of a signal. In contrast to this, LEOsats will only have a particular area of the Earth in sight for less than 10 to 20 minutes, and also must record and store any signals of interest for later download when over a control station. The short time available for download (10 to 20 minutes say 4 times a day) severely limits the spectral bandwidth that can be monitored by a LEO COMINT asset. Such satellites must thus be frequently retasked to monitor different small segments of the total radio spectrum.
A satellite in geosynchronous orbit can see approximately one third of the Earth’s surface and it remains stationary or nearly so with respect to a ground station. This allows such a satellite to monitor a large part of the Earth’s surface and to continuously downlink to a fixed station in ‘friendly’ territory. Because of this, almost the entire radio spectrum may be monitored and downlinked in real-time. However, the downlink frequency must be extremely high to cope with such a wide bandwidth. This necessitates the use of frequencies that are subject to significant attenuation by water vapour in the Earth’s atmosphere, and the placement of ground stations in low rainfall areas is often desirable. The disadvantage of geosychronous orbit is that the sensor is always at a great distance (a minimum of 36,000 km) from the desired signal. This implies a need for very large receive antennae, if low power signals are to be received.
It is believed that US space based COMINT assets have deployed the largest space structures ever made, as antennae, some around 40m in diameter. American SIGINT satellite Orion has a 255 feet diameter unfurlable antenna which can detect signals from a wristwatch-sized radio. Orion satellites are used for intercepting missile telemetry/datalink signals and monitoring microwave traffic.
SIGINT has traditionally been considered an inherently governmental function . Now Kleos, a new start-up in Luxembourg, hopes to sell geolocated radio frequency (RF) data as an intelligence service for ministries of defence (MoDs) and other security stakeholders. There is also growing utilization of miniaturized satellites for military and defense applications.
Signal Intelligence
Electronic Intelligence (ELINT) primarily deals with radars signals. An ELINT system intercepts radar signal and analyzes it i.e. determines the frequency of carriers and subcarriers, modulation, bandwidth, power level, beam footprint parameters, and emitter location and motion. Basically, it creates an RF signature of a radar which can be used for locating and quickly identify the radar in subsequent encounters. Furthermore, based on RF signature information of a radar, jamming techniques can be developed to counter the radar. This is the reason why IAF avoids using the radars of its fighters in joint exercises.
Communication Intelligence (COMINT) involves recording and analysis of communication signals. Intercepted COM signals are demodulated and the original data (audio, video, text) is extracted. Since military communications are usually encrypted, analyzing them requires more sophisticated equipment. Therefore, COMINT systems are more complex than ELINT systems.
Foreign Instrumentation Signals Intelligence (FISINT) is similar to TELINT (telemetry intelligence). It involves interception and analysis of non-communication signals (missile/UAV telemetry signals, missile tracking/arming/fusing commands, locator beacons). A FISINT system is more comprehensive in nature. It not only determines the configuration and capability of emitter but also the overall system emitter is a part of.
China’s SIGINT satellites
ELINT satellites provide the detection and identification of radar signals emitted by ships and thus provide the cues to the EO and SAR satellites to track ships in the oceans that could threaten China’s core interests. They are backbone space component of China’s Anti Access and Area Denial strategy. China’s ELINT programme has evolved considerably since the launch of its first satellite in 1970.
A fourth trio of Chinese Yaogan military satellites with secret missions launched on Jan 25 aboard a Long March 2C rocket from the Xichang space base in China’s Sichuan province. The spacecraft join nine others launched into similar 370-mile-high (600-kilometer) orbits on three previous Long March 2C flights from the Xichang spaceport Sept. 29, Nov. 24 and Dec. 25. The latest triplet of Yaogan 30 satellites lifted off at 0539 GMT (12:39 a.m. EST; 1:39 p.m. Beijing time) Thursday, Jan. 25, from the mountainous Xichang launch site in southwestern China. State media reported the satellites will be used for electromagnetic observations and other experiments
In March 2010 China placed its first triplet of ELINT satellites into an 1100 Km, 63.4 degree inclination orbit. Its orbit characteristics make it very similar to the early US Ocean Surveillance System. China appears to have at least three operational Yaogan ELINT clusters (they have launched five triplet clusters since 2010) at any given point in time.
China appears to now replace its three-satellite Yaogan ELINT cluster with a two satellite cluster like the US. Shijian-16-01 is the first of a new series that will succeed the Shijian-6 series that consists of four pairs with two satellites each. The Shijian-6 satellites were launched between 2004 and 2010.
The second in the first pair of Shijian-16 signals intelligence (SIGINT) and electronics intelligence (ELINT) spy satellites designed to spy mainly on the United States military in Asia has now reached its inclined orbit 600 kilometers above the Equator.
Shijian-16-02 joins its sister satellite, Shijian-16-01, launched in October 2015 in the same orbit. The orbit of both spysats inclined 75 degrees to the Equator is an unusual orbit that makes it easier for both spysats to intercept encrypted signals from the US military. These intercepted electronic signals will then be analyzed and decoded by Chinese.
CERES SIGINT Satellite System
CERES (CapacitÉ de Renseignement Électromagnétique Spatiale) satellite system, the first operational space-based signal intelligence (SIGINT) system of the French Ministry of Defence, is scheduled for launch in 2020.
CERES is a constellation of three satellites that are intended to detect, locate and characterise electromagnetic signals on the ground, emitted by enemy radio communications systems and radars, to provide space-based early-warning and ballistic missile detection capabilities for the French Armed Forces. The satellites will also help to improve situational awareness and security in the battlefield.
Airbus Defence and Space, Thales Airborne Systems and Thales Alenia Space are the prime contractors for the CERES satellite system. French defence procurement agency Direction générale de l’armement (DGA) will provide project management services for the CERES programme.
The all-weather CERES satellites will carry signals intelligence payloads to detect high-frequency radio waves and other electronic signals. All information captured by the payloads will be down-linked for processing by the associated ground segment.
The CERES constellation will be located in low Earth orbit at an inclination between 70° and 80°, to detect and locate electromagnetic signals simultaneously at different time intervals. The satellites will be positioned in a triangle shape (satellite 1 / satellite 2, satellite 2 / satellite 3, and satellite 1 / satellite 3) in close proximity to each other. They will be powered by deployable solar arrays and batteries. The ground control unit consists of two systems, one to command and control the spacecraft and the other to perform mission planning and data processing.
Russia’s ‘Liana’ Satellites Can Keep an Eye on Ships, Subs or Even Fishing Boats
The Liana network will locate ground-level radio signal emissions from both stationary and moving objects of various size, from ground and sea-based installations to enemy vehicles and vessels. According to military experts, the system’s Lotos-S satellites will be tasked with ground surveillance, while Pion-NKS satellites will be charged with monitoring the seas.
The Soviet predecessor to Liana was the Legenda, system built during the Cold War which used a network of US-P Signals Intelligence (SIGINT) and US-A ELINT satellites. That system was designed as a reconnaissance and targeting system for Soviet nuclear and anti-ship cruise missiles targeting US and NATO carrier groups and fleets.
Luxembourg start-up aims to sell signals intelligence as data service
Kleos, a new start-up in Luxembourg, hopes to sell geolocated radio frequency (RF) data as an intelligence service for ministries of defence (MoDs) and other security stakeholders. Its strategy is to use small satellites flying in low-orbit formation to collect the data: a technological solution that can be scaled to fit customer demand, company officials said. Bowyer said the company’s data “will be about tipping and queuing: using radio frequency information to refine and point to other sources of intelligence. It will help narrow down the field of search for users.”
The first step will be to get its initial cluster of nano-satellites, each weighing 9 kg, into a low-altitude polar orbit. Danish company GomSpace A/S will build and ship the satellites to New Zealand for launch by US aerospace company Rocket Lab in June 2019. A second cluster is to be launched by the end of the year. Once in orbit, the satellites are to fly in formation about 50–100 km apart: a separation that officials said was sufficient for differential, time-based surveillance and measurement of signals (a technique known as multilateration).
“Essentially, each satellite will be a sensor and the cluster will function as a giant [multiheaded] antenna able to collect all kinds of RF signals,” Bowyer said. Such signals include those from satellite phones, mobile phones, maritime VHF, radars, defence systems, or walkie-talkies on ships that have deliberately turned off their official automatic identification system (AIS) locational signal, he said.
“This will require a lot of effort to do the separation work to determine whether the data indicates just one or many signals layered on top of one another,” Bowyer noted, “but once we have the information, we’ll be able to create geolocation maps at an increasing rate of refresh, depending on how many clusters we put up in the sky.”
With one satellite cluster, Kleos’s data refresh rate will be every 10–24 hours depending on the transmission power of targeted signals. This would improve to a refresh rate of every 0.5–2.5 hours with 10 clusters and to real-time refresh with 20 clusters. Ideally, he said, a mini-constellation of five clusters for a 1–5 hour revisit time would be the initial goal.
How long it would take Kleos to reach real-time refresh will depend on customer demand. “Twenty clusters isn’t necessarily the goal; if there was only one customer for that it wouldn’t be cost-effective,” said Bowyer. “But the advantage of a three-month commercial launch cycle is that it gives us great flexibility, which doesn’t exist in government cycles.”
ISRO’s EMISAT: Electronic Spy in Space
EMISAT is an advanced electronic intelligence (ELINT) satellite jointly developed by ISRO-DRDO. It has a basic architecture similar to HySIS (based on Small Satellite Bus-2) which was first used in SARAL satellite. The satellite has been under development for nearly 8 years. The ELINT payload of the satellite was developed under project KAUTILYA by Defence Electronics Research Laboratory (DLRL), Hyderabad. The project was first acknowledged in the Ministry of Defence annual report 2013-14.
EMISAT is a small satellite i.e. it weighs less than 500kg. It is likely to be placed in a highly elliptical orbit (signature SIGINT satellite orbit) so as to maximize dwell time over specific signal recording area.
References and resources also include:
https://www.airforce-technology.com/projects/ceres-sigint-satellite-system/
https://janes.ihs.com/InternationalDefenceReview/
https://mark20x.blogspot.com/2018/12/isros-emisat-electronic-spy-in-space.html
