The commercial drone market is rapidly growing, making them widely available as a threat to security for both commercial and military institutions and gatherings. The recently reported drone attack in Venezuela is the first possible attempt to assassinate a government leader but shows how dangerous this threat is to open air speeches and public gatherings.
According to Global Market Insights, the commercial drone market in 2016 was more than 100,000 units with a market value of more than $2 billion and is anticipated to grow at around 25 percent CAGR through 2023. According to MarketsandMarkets, the overall drone market is expected to grow from $17.8 billion in 2017 to $48.9 billion by 2023, at a CAGR of 18.32 percent during the forecast period. The market research firm sees the driving factors as the increase in venture funding, rise in demand for drone-generated data in commercial applications and rapid technological advancements.
While the development of commercial UAVs has primarily been for video and photography, their capabilities are now being used in agriculture, real estate, construction, delivery and media. But civil drones that are used for non-military purposes bring vulnerability to cyber-attack and misuse. Hackers can take control of them for criminal activity, and terrorists can use them to deliver weapons so demand for detection and counter systems is growing rapidly. Two leading RF test & measurement companies leading the way in this market are Rohde & Schwarz and Aaronia. Each company has supplied details about their systems which we have consolidated here.
ROHDE & SCHWARZ—Meeting the Challenge of Detecting and Countering Drones
In response to increasing demand from governmental authorities, ESG Elektroniksystem- und Logistik-GmbH, Diehl Defence and Rohde & Schwarz formed a partnership in 2015. The objective was to set a global benchmark for new drone detection and countering solutions. This cooperation resulted in the three companies creating GUARDION, an effective solution for detecting and countering drones. GUARDION has been successfully deployed at several events, such as the G7 summit in 2015, the G20 summit in 2017 and the ILA Berlin in 2018. Based on this early experience, the partners identified the following requirements as crucial for effective drone detection and countering:
- Modularity, scalability and flexible system configurations: Due to the broad range of potential scenarios, systems need to incorporate various sensors and countermeasures, be individually scalable to meet the requirements of both client and operations and provide deployment capabilities for man-portable, vehicle-based, container-based and stationary platform integration.
- Automatic and reliable multi-sensor detection and classification: To minimize both operator interaction and the false alarm rate, systems must offer automatic detection and also classification of both drone and drone pilot, reliably differentiating drones from other flying objects.
- Full-scale command and control system: To improve shared situation awareness, systems must be equipped with a command and control (C2) platform providing a comprehensive operational picture, fusing all data from sensors and disruptors, showing all assets on a digital map and offering means of communicating this information among all forces, securely and in real-time.
- Effective countermeasures: To effectively tackle identified threat assessments, systems must provide a broad portfolio of multiple countermeasures targeting all common control mechanisms with minimal to no effect on other uninvolved third parties within reach and optimized use cases for the national legal framework they are to be operated in.
Total System Solution
The three companies have combined their relevant solutions in the GUARDION system that consists of the following subsystems (see Figure 1):
- ESG’s TARANIS® C2 system
- R&S®ARDRONIS RF drone identification and countering system
- Diehl HPEMcounterUAS electromagnetic pulse sources
For technologies not covered by the alliance companies, they searched the market for the most suitable and reliable products from other suppliers. Their continuous and competitive market research included not only constant testing and portfolio development, but also active operation. The following summarizes the results in the areas of C2 (connectivity and interoperability, data fusion and situational awareness), multi-sensor (RF remote control analysis and DF, radar detection, acoustic recognition and camera verification) and multi-counter capabilities (smart RF control link disruption and high-power electromagnetic pulse).
Command and Control
Sophisticated C2 systems provide the advantage of connecting all subsystems, sensors and disruptors. ESG’s TARANIS® makes particularly complex large-scale scenarios with multi-sensor setups and potential multiple threats more manageable (see Figure 2).
Interoperability with national and international military command and control centers enhances communication and allocation of forces and facilitates their interaction and coordination, even in a dispersed or remote setup. Network-capable C2 systems allow crisis centers and mobile mission forces on the ground to assess, share and communicate relevant information securely and in real-time.
Data Fusion and Situational Awareness
The core intelligence must fuse and analyze all incoming sensor data, visualize the incoming drone and the threat location and track the movement of the drone pilot, own assets and security personnel in real-time. Ideally, all relevant additional geo-information from the scenario (grid reference, etc.) can be integrated and fed into the C2 system.
The C2 system displays all information on a comprehensive map-based situational picture, so a single operator can monitor and control the overall system. This improves situational awareness, enhances operators’ capacity to launch and coordinate appropriate countermeasures ranging from organizational action to technical jamming to lethal deactivation.
RF Analysis and Direction Finding
Drones are usually remote controlled via a radio link. RF sensors can intercept these specific emissions that reveal the presence of a drone. The R&S® ARDRONIS system not only detects the remote control transmission, it also classifies the type of the drone and the manufacturer of the remote control unit signal (see Figure 3). When using direction finders as RF sensors, it can also determine and visualize the direction or location of the remote controller.
This is usually the location of the drone’s pilot, which is often as important as the drone’s position.
If the drone streams video or other data, RF sensors can also intercept these emissions. The systems can take bearings on the drone and visualize them on a digital map. With two direction finders, RF sensors can take cross-bearings, allowing them to calculate both the pilot’s and the drone’s geographic location. When demodulating/decoding the video downlink, they can view the content on the workstation or operator’s laptop. Security personnel can then monitor what the drone pilot sees on their screen.
A main advantage of the RF sensor is that it receives the remote control link as soon as the remote controller is switched on. At this point, the drone is still on ground. Alerting security personnel even before the drone takes off is a benefit that only an RF sensor can provide. RF sensors detect the remote control link as soon as it is switched on and alerts operators early, before the drone becomes a threat.
RF sensors continuously scan all relevant frequency bands used by commercially available drones. Common frequency bands of drones’ remote control are 2.4 and 5.8 GHz, but other bands are also possible, such as 433 MHz. The system allows individual configuration.
The detection range of a typical remote control unit with 100 mW output power is around 1.5 km, depending on the type of drone, the frequency band used, the transmission power, antenna height and other factors. Some drones use Wi-Fi technology, which allows them to be controlled via smartphone or tablet, though the remote control range is reduced. In this case, the radio control cannot be detected by analyzing the physical layer. It is necessary to analyze the WLAN protocol itself. Special RF sensors can detect and recognize these Wi-Fi signals from drones and also indicate the drone manufacturer.
RF sensors automatically analyze the intercepted signals. They can distinguish between the different manufacturers and even the type of the commercially available drones by comparing the detected emission with a profile library where typical technical parameters of commercial drone RF remote controls are collected. Users can record unknown remote control transmissions to extend the system’s signal library. This allows them to later recognize previously identified signal profiles.
Radar can detect distant objects and determine their position, speed and material composition. The main advantage is their wide range, but they do need line-of-sight with the target. For drones that are not controlled via RF data-links, radars are the primary sensor for drone detection and location.
GUARDION uses drone detection radar units specifically designed to meet the challenges of drone detection. Its antenna rotates at a speed optimized for high update rates in order to track targets while scanning and has a high signal-to-noise ratio to prevent false alarms. The preferred radar is an enhancement of FMCW radar that is widely used for detecting birds at airports. It is optimized for recognizing non-metal objects with small radar cross sections. With the implementation of special micro-Doppler technology and software algorithms, the X-Band radar is now optimized to recognize the rotating propellers on drones. This results in excellent distinction between drones and birds and other small flying objects. It also provides distance information for drones already detected with the RF direction finder and is able to detect and track multiple targets.
The radar covers the full 360 degree field of view in azimuth with 10 degrees in elevation. It can detect larger fixed wing targets at a range of up to 5 km and professional multi-rotor drones at up to 3 km with a classification range up to 1100 m. Typical commercial drones, such as the Phantom III, can be classified within a range of 700 m. An integrated PTZ camera allows instantaneous verification of detected drones.
By cueing cameras and disruptors to the radar, operators can optically verify the presence and threat potential of detected objects before launching countermeasures and log video recordings to preserve evidence. With open system architecture, EO and IR sensors can be integrated as needed to meet the individual requirements of customers and scenarios. Examples include dome network cameras and surround cameras based on CMOS sensors as well as high performance sensors. However, advanced optical equipment and sophisticated algorithms are needed to support optical tracking and identification.
In urban scenarios, acoustic sensors are often used to cover the blind spots of the radar or RF sensors since they provide non-line-of-sight (NLOS) drone detection capability. If, for example, a building is blocking the view of primary radar sensors, an additional acoustic sensor behind the building can be used for coverage. Acoustic detection also lowers the overall system false alarm rate when used in combination with other detection sensors. As a passive sensor, the acoustic sensor has the advantage that it does not emit a signal. All flying systems produce specific sound patterns that are difficult to conceal. The sound patterns of drones are highly recognizable and completely different from the patterns of other flying objects.
The detection range of an acoustic sensor greatly depends on the size of the drone. A typical acoustic sensor used with the GUARDION system offers excellent detection and sensing capability based on advanced multi-microphone arrays. The system is able to scan the horizon by calculating time-of-flight differences in the acoustic patterns. These phased microphone arrays can extract the azimuth and elevation angle of incoming sound sources at distances of up to 500 m.
Disrupting the Drones Control Link
The R&S®ARDRONIS remote control jammer can stop drones by interrupting the command signals. If the drone loses its remote control signal, it usually goes into a fail-safe mode that causes it to land or return to its takeoff position. Jamming therefore prevents drones from entering a specific airspace.
The drones’ remote control units usually use frequency hopping methods instead of fixed frequencies. Smart jammers follow these frequency hops and disrupt only those bursts that control specific drones. These jammers minimize the effect on other drones or radio transmissions in the same frequency band.
Wi-Fi controlled drones require a different method for countering. Once detected by the RF sensor, their network parameters are known. This allows systems to transmit a command that disconnects them from the remote control unit. This will force them into fail-safe mode, preventing the drone from continuing on its course.
Jamming is successful when the jamming signal is powerful enough to disrupt the RC signal when it arrives at the drone. This depends on many factors such as the distance between the antennas (and their height), the orientation of the antennas (especially the RC antenna), line-of-sight conditions, the presence of other strong signals in the area and environmental effects such as reflection and refraction.
Smart jammers need much less power than other types of jammers. The low power approach means jamming is possible at a distance about twice as far as the distance between the drone and the pilot’s RC—under good line-of-site propagation conditions.
In waypoint mode, drones fly their course without a remote control signal. In this mode, they usually rely on a global navigation satellite system (GNSS). To stop the drones in such a case, a GNSS jammer can interrupt the reception of the weak satellite signals to prevent navigation. Directional antennas are used to direct interference signals toward the drone on the relevant GPS, GLONASS or Galileo frequencies.
High-Power Electromagnetic Pulses
High-power electromagnetic (HPEM) pulses are a new generation of disabling technology for countering drones. Developed and manufactured by Diehl, the HPEM disruptor disables the drone’s ability to fly—a last resort measure (see Figure 4). Unlike other systems based on jamming the drone’s remote control links or navigation aids, the HPEM source directly impacts the semiconductors of the control electronics on the printed circuit boards inside the drones by means of electromagnetic pulses high enough in power to disable their operation. HPEM is effective in all flight modes, whether flying autonomously or radio-controlled, the drones become inoperable upon impact of HPEM pulses. There is no time delay. HPEM systems offer scalable ranges and can simultaneously eliminate the threat of entire swarms of mini-drones. HPEM systems are capable of disabling the drone’s control electronics, regardless of the control method. The system immediately stops drone intrusion. The Diehl HPEM counter UAS does not cause harm to individuals and is approved for use in civil areas.