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SIGINT capability for Special Operations Forces


SOF (Special Operations Forces) are required to carry out activities with the highest levels of discretion in hostile and often unfamiliar environments. In these scenarios, real-time RF situational awareness is a vital element both in ensuring your own forces remain undetected and in detecting enemy activity. However, the need for this vital capability must be weighed (literally) against the need for forces to be able to carry the equipment and remain agile.

So what situational awareness can be gained from RF signals, even using exclusively man-portable equipment?


For SOF, having freedom of manoeuvre in the Electromagnetic Environment (EME) is imperative. Simply asking “How advanced can my SIGINT capability be?” risks soldiers becoming overloaded with every piece of equipment that may be useful to them. There is no point having a high-level of awareness of the surrounding EME if you are unable to move or respond effectively to the situation. “How much spectrum intelligence capability can forces carry?” can lead to the same problem. A soldier may be able to carry 150 lbs, but that does not mean they have to. No matter how capable a SOF team is, they will perform better physically with as light an equipment load as possible. Any additional capability has to justify the additional weight, and where exactly that tradeoff lands will be determined on a mission by mission basis.

RFeye systems from CRFS allow SOF teams to maintain spectrum intelligence and situational awareness of the EME by putting SWaP (Size, Weight and Power) at the centre of its design philosophy.


Real-time RF situational awareness up to 18 GHz

SOF teams can gain a greater understanding of their surroundings by adding knowledge of the EME to their overall operational picture. In practical terms, that means being able to see signals from 9 kHz all the way up to 18 GHz in a package that can still be comfortably carried. Situational awareness can then be gathered on everything from enemy radio, aircraft, radar, and both military and commercial satellite communications systems.

However, many of the high-performance radio receivers available today were not designed to be SWaP-optimized from the outset, as they were intended to be deployed in vehicles, or at fixed locations. As man-portable equivalents have been developed this has consequently led to significant compromises in performance including frequency range and sensitivity. However, receivers like the RFeye Node, which were designed with low SWaP as a guiding principle, have resulted in portable packages such as the RFeye Stormcase or Backpack that are inherently performance-weight optimized.

Exceptional receiver sensitivity also means that any signal of interest can be detected at a much greater range. Early detection of signals can lead to tactical advantage in the battlefield enabling plans to evolve rapidly through a greater understanding of the operational environment, including the EME.

As well as using spectrum to see what the enemy is doing, it is important to make sure your own forces are not detected by the same means. EMCON (Emissions Control) can usually be assured by having the correct procedures in place to avoid devices being left on or switched on during periods of radio silence. However, spectral awareness can provide an extra layer of protection against equipment malfunction or even simple human error.

Direction Finding (DF) and geolocation

To safely navigate in hostile environments, you often want to know not just that a signal is present but where exactly it is coming from. Locating signal sources can help you avoid potential threats and target enemy forces, insurgents or infrastructure. However, direction finding is one of the hardest capabilities to make portable, as low frequencies will always require large antenna arrays. Direction finders which go as low as VHF frequencies will generally be vehicle-portable, but not man-portable. Lightweight and tripod-mountable RFeye Arrays which can be readily packed away into a carry case while Backpacks with direction finding wands can be used for all your RF situational awareness needs and provide DF down into the UHF band. With just one of these devices your forces are than able to tell where enemy transmissions are coming from and take appropriate action. Portable direction finding with a single array can be used to build up a geolocation over time and pinpoint the exact origin of enemy signals by taking multiple measurements from different locations. Alternatively, if the enemy are on the move it is possible to create a track of their movements based on the changing bearing received over time.

Alternative geolocation methods and 3D geolocation

An alternative approach to geolocation from using DF systems is to use TDOA geolocation, which relies on multiple fixed or semi-fixed receivers being deployed in the field. These receivers can easily be installed in Forward Operating Bases, vehicles or by using the man-portable RFeye Stormcase. To geolocate an enemy signal requires a minimum of 3 receivers to determine the lat/long of the enemy to within a few 10’s of metres. 3D geolocation (ideal for aircraft & drone tracking) simply requires the addition of one more receiver, which itself does not have to be at any particular altitude.

Another alternative is a pop-up or fly-up network using receivers mounted on small drones. This also means that receivers can rapidly be deployed over areas you would otherwise have difficulty entering, or would not want to send forces into directly.

Creating a distributed network on the fly (pun intended) may not always be feasible, but where it is, the benefits can be significant. The frequency range of signals that can be located is greater. The systems are man-portable and once the units are deployed as a distributed network on the ground or in the air, the weight burden is zero.

The need for 3D geolocation has never been more important than it is today given the significant threat from drones flown by insurgents to attack friendly forces. Insurgents are able to easily obtain commercial drones and use them for surveillance or, more shockingly, weaponize them. A 3D geolocation solution provides front-line forces with a capability and information only previously accessible by headquarters staff.

Signals intelligence – Record and post-analysis

Gathering information prior to, during, and post operation is key to providing intelligence for future operations. Signals intelligence can provide significant insight into the plans and tactics of enemy forces. This is enabled with lightweight RF recording systems, which can be used alongside a laptop, to record signal information in high-fidelity. This information can be classified, exploited and even geolocated in post-mission debriefings adding real operational advantage to the planning phase of the next operation.

When selecting RF monitoring, geolocation and recording systems for SOF operations a balance needs to be maintained between mission outcome and equipment load. Optimizing the capability-weight ratio is key to enabling mission success whilst being fully aware of the surrounding EME and the opportunities to exploit the intelligence gathered from it.

Get in touch and find out how you can better optimize your systems with CRFS.

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