Can Drones Improve Geolocation?

The number of RF interference incidents is on the rise. Of course, proportionally, this would be expected; we are seeing growth within satcom on an exponential scale. Satellite numbers sit at over 12000, a stark contrast to 2019 when only approximately 2000 satellites were in orbit. Naturally, the ground segment has reflected this growth, with many additional antennas and terminals deployed to deliver services. RF Interference has long been an issue with satcom, and its impact is costly to operators. Throughput is affected, services can be disrupted, and ultimately, profitability can suffer. We must also consider the impact of geopolitics on RF Interference; the International Telecommunication Union (ITU) has noted an increase in the number of reports of intentional jamming, which impacts users by blocking the use of certain frequencies. Prior to newspace, RF Interference was often associated with mispointing, faulty equipment, and comms-on-the-move. To minimize the impact of RF Interference, the industry introduced standards, called SOMAP (Satellite Operators Minimum Antenna Performance), to ensure that the ground segment consisted of high-quality equipment. Additionally, emphasis was placed on training to ensure that installation and maintenance were done correctly.

Comms-on-the-move terminals introduced a challenge because of their nature; it is harder to manage RF when the antenna itself is moving. This is important to consider when understanding the challenges in the current ground segment landscape. Beyond the sheer numbers, networks have become more complex. Lower Earth orbit satellites appear to move across the sky, meaning that they must be tracked by the antenna they are communicating with. To respond to this demand, phased array antennas are now commonplace in the field, addressing the technical complexity of this tracking and switching. But by design, this introduces an inherent layer of movement. Through beamforming, phased array antennas create a high-gain directional beam that can be steered in any direction. Additionally, each antenna can create multiple beams to track multiple satellites at one time. This is a far more complex operation than that of a traditional parabolic antenna, and therefore, more difficult to avoid RF Interference. So, how is the industry responding to this increase in RF Interference?

RF Interference: To Be Expected?

There has been a shift in attitude towards RF Interference. Before, the industry appeared to focus on reducing the number of incidents. Now, as the industry grows, it anticipates that RF Interference will happen, and importance is placed on how it is resolved. Regardless of whether interference is deliberate or accidental, locating the source of RF Interference is a complex task; dynamic networks that boast a vast number of terminals make it extremely difficult to pinpoint which antenna is causing an issue.

One of the principal tools currently used by operators is geolocation. By using satellites to monitor and compare RF signals, it is possible to triangulate the general area from which interference is being transmitted. This narrows down the region in which to look for the source; however, it is unable to identify its exact location. This can be enough in a remote region, where there are few options, which can cause the issue. However, as more and more terminals are introduced to the ground segment, geolocation’s lack of accuracy makes it challenging to pinpoint the culprit. Operators are often required to send engineers to the area to identify the issue. This is a costly solution which takes time; manually searching the area could take days, especially when considering that interference is often intermittent and therefore difficult to detect.

Getting to Grips with Source Identification 

The challenge of the satcom industry is swiftly becoming its scale. Deploying teams of engineers to identify RFI is quickly going to be unsustainable when considering how often these incidents occur. Business cases within satcom require efficiency, and ultimately, this method is in need of updating. This update comes in the form of UAVs. Due to their proximity to the ground, UAVs offer a far more in-depth overview of the RF landscape below. They can clearly measure signal strength and direction, whilst continuously refining the target coordinates during the flight, meaning that it is a fast and cost-effective alternative to relying solely upon ground engineers.

UAVs are equipped with a directional horn and gimbal and launched from optimal launch positions based on signal characteristics, expected detection range, and surrounding terrain. The UAV then performs angular scanning of the area, enabling detection from multiple spatial perspectives, therefore increasing the likelihood of capturing the interference signal. This sweep of the target area gathers data on signal presence, strength, and angle of arrival. This data can then be analyzed to narrow triangulation through repeat scans, ultimately identifying the source.

The Wider Benefits of Source Identification

In military operations, being able to effectively identify spectrum and signals of interest can help forces gain a valuable battlefield advantage. Having spectrum intelligence delivers a decisive edge, as well as the option of neutralizing a few key enablers, which can have cascading effects across the entire enemy force.

However, this kind of spectrum intelligence has been challenging for the defense sector in the modern battlefield, where they are operating across vast distances and often subject to electronic warfare techniques such as jamming and spoofing of signals. At the same time, no two scenarios are the same. Being able to use the appropriate drone (or even other platform) for the right circumstances and quickly and easily detect these signals in the midst of conflict is a game-changer.

Understanding the Role of UAVs in Managing RF Interference

UAV geolocation will not completely replace traditional geolocation methods. The technology will improve the efficiency of identifying sources of interference in complex spectrum environments. As the ground segment grows and RF management becomes more challenging, there is a need for tools and methods to advance in their capabilities. Utilizing UAV technology will enable quicker identification of RF Interference at a lower cost, supporting operators to maintain cost-effective business cases. This is fundamental in an industry that is seeing rife competition; businesses must maximize revenue and provide reliable services. Without this, customers could be lost, or businesses could become unviable.

RF Interference is an old problem that is now commonplace and accepted. However, its damage must not be underestimated. It is costly, both financially and reputationally. Geolocation is a brilliant tool in identifying sources of RF Interference; however, a key part of its benefit is the quick identification of the source to allow service performance to resume. As the landscape grows, traditional methods are being outgrown. UAVs provide a quick and cost-efficient way of homing in on service disruptors, enabling the industry to drive efficiency on the ground in a complex environment. As this complexity grows, so does the need for quick RF Interference source identification.