As an essential part of modern warfare, Signal Intelligence (SIGINT) has become a critical element of intelligence collection, understanding of enemy intentions, and assessment of battle positions and capabilities. These capabilities are required in peacetime, low-intensity conflicts as well as in conventional warfare. Collected by ultra-sensitive receivers scanning a broad range of the electromagnetic spectrum ELINT (Electronic Intelligence) and COMINT (Communications Intelligence), known collectively as SIGINT, monitor communications, microwave and radar systems, measures, locates, and analyses the spectral signature of such emitters. The result is an electromagnetic situational picture known as the ‘Electronic Order of Battle’ (EOB) - an essential part of a modern intelligence assessment.

As the battlefield becomes more connected, sensor-based and network dependent - the more it can be exploited by SIGINT measures. By analyzing the location and characteristics of signals, their patterns and interactions between separate system elements, SIGINT gains an insight into enemy activity and state of alertness that are hard to get by other intelligence means. Another factor that contributes to the growing importance of COMINT in collecting intelligence is the emergence of asymmetrical warfare, where communications is often the only signature for enemy activity when the adversary is immersed within a civilian population.

Seeking to detect even the smallest changes in EOB, SIGINT routinely monitors the distribution of emitters over an expansive area and wide frequency range. Following routine activity or detecting changes in the patterns or activity modes can indicate potential development and escalation of threats.

Airborne SIGINT
Traditionally performed from ground or naval platforms, SIGINT activities transition to airborne SIGINT platforms is considered the most advantageous for such missions - for their long range, persistence and mission flexibility. Such systems are made up of manned and unmanned platforms that carry an array of ELINT and COMINT sensors tailored for the specific collection needs.

Airborne systems can intercept signals at a greater distance thanks to a longer line of sight than ground-based systems. When necessary, airborne SIGINT assets can be deployed across enemy lines in order to intercept signals otherwise out of reach of ground-based systems.

Airborne systems are easily deployable to remote areas in support of specific missions or troops deployments, thus provide intelligence prior and during operations. In case of need, airborne platforms can be easily re-tasked and assigned to a different area.

Advanced, manned airborne SIGINT platforms are equipped with ample onboard processing power and operating workstations, allowing analysts to view and analyze information immediately, quickly relaying to forces on the ground. 

Performed from high altitude and high-speed flying platform, airborne SIGINT provides superior emitter triangulation accuracy, based on the technical parameters obtained with the sensors on board.

The Business jet Advantage
In recent years sensors and computing power have undergone dramatic changes. With the exponential growth in processing power, SIGINT systems have also been reduced in size, weight and power consumption. Miniaturized electronics, microwave components, and advanced antennae technology, turned systems that weighed hundreds of kilograms and filled entire cabins into few LRUs that automatically perform missions that required dozens of skilled operators in the past. This trend has enabled the shifting of SIGINT mission to smaller aircraft (business jets) platforms or even unmanned aircraft systems (UAS).

ELTA Systems, a division of Israel Aerospace Industries is one of the pioneers in this field. With dozens of systems delivered and operational by air forces and government agencies in five continents, the company is positioned among few experienced integrators of special mission aircraft system.

Over three decades the company has developed and integrated SIGINT on many types of aircraft, with Boeing 707 and IL-76, representing the large platforms. Due to its ability to manufacture smaller, smarter and more accurate sensors, ELTA was able to install and integrate more sensors on smaller platforms. For example, modern operationally proven SIGINT platforms utilize highly efficient business jets such as the Gulfstream G550 and even smaller applications, including UAV of various sizes. 

ELTA was one of the first companies to recognize the benefits of using business aircraft as special mission aircraft. Starting in the early 2000s, following comprehensive study of alternatives, ELTA teamed with Gulfstream to convert the G5 business jet into a versatile special mission platform to assume strategic, military role. Today, ELTA Systems has a proven and successful track record of integrations on several types of business jets, including Gulfstream G5, G550 platforms, for customers including the Israeli, Indian, Italian and Chilean air forces and government agencies.

As the use of specialized business jet increased, ELTA has teamed with more platform manufacturers, thus being able to offer the most suitable solution for the user. Teaming with Airbus, Gulfstream and Bombardier, ELTA provides system design and airframe modifications, large types of sensors and system integration.

Designed for passenger comfort and operational efficiency, business jets offer a spacious cabin, along with power and cooling resources necessary for all systems operation. The cabin accommodation provides comfort operating conditions for the crew, even on extended day-long missions. One of the benefits of business jets is the cabin pressurization set to a level equivalent to 5,000 ft. of elevation, thus reducing operator fatigue. Large fuel capacity and engine economy together with low sensor SWaP (Size, Weight and Power) allow use the aircraft to its maximum endurance without aerial refueling, operating all mission systems and with a full crew on board. By being able to fly over 45,000 feet, the platform covers hundreds of kilometers in each direction. Quick turnaround between missions, high reliability, and low operating costs enables users to maintain 24/7 operations even with a small fleet.

Always in Command
With their extensive communications facilities and spacious cabin, SIGINT aircraft are often used as airborne command posts (ACP), in addition to their SIGINT role, providing the advantage of close loop between the intelligence source and decisions makers, which is particularly relevant in emergency, long-range operations.

Special mission aircraft are configured to address specific user requirements. As such, SIGINT aircraft can be designed exclusively for this role, or integrate with other sensors on board, including phase array radars, Synthetic Aperture Radar / Ground Moving Target Indicator (SAR/GMTI), in addition to SIGINT sensors. Use of Line Of Sight (LOS) and Satellite Communication (SATCOM) allows for real-time communication between onboard operators and ground stations, thus enabling the crew to offload processes and workload to a central ground-based facility, while real-time data processing on board, enable the crew to rapidly respond to dynamic situations and support missions as flying command posts.