Drone alert!

The Market for Small Commercial Drones

The market for small commercial drones is booming. However, these inexpensive and easy-to-fly devices also pose security problems. The R&S®ARDRONIS drone monitoring system helps businesses, government authorities and critical infrastructures to protect personnel and goods.

Commercial Drones: The Next Big Thing

Incidents with commercially available drones appear almost daily in the media: drones in the vicinity of airports or even in the flight paths of aircraft (e.g. Heathrow, Munich, Warsaw, Taipei), drones above power plants and governmental buildings (the Japanese Prime Minister's office, the White House South Lawn), drones at political events (German Chancellor Dr. Angela Merkel's election rally in Dresden), drones above automotive test tracks or in the skies over Paris.

Currently, more than 300,000 drones are sold per month through online shops or brick-and-mortar stores around the world. In the USA alone, about one million devices were sold in the weeks leading up to Christmas 2015. It is estimated that by 2025 the commercial drone market will reach a volume of more than 8.5 billion euros. The explosion of relatively inexpensive and easily operated flying drones represents a new type of challenge for the protection of public and private spaces. The devices – which are both readily available and easy to fly – provide ample opportunity for misuse. Difficult to detect and capable of carrying payloads up to a few kilograms, drones increasingly represent a threat to critical infrastructures and public figures and at public events. Security agencies, government authorities as well as private organizations and facilities that require protection must have the technological approach to counter this threat.

The first challenge is to detect these small flying objects, and a number of methods are available to accomplish this. Once detected, the intruder must be classified in order to determine whether countermeasures are necessary. Instead of visual detection or radar monitoring, the Rohde & Schwarz solution identifies, finds the direction of and disrupts radio control links to and from the drone. The R&S®ARDRONIS automatic radio-controlled drone identification solution from Rohde & Schwarz has already proven itself in operations requiring the highest level of security, such as the June 2015 G7 summit held at Elmau Castle in Bavaria, Germany, and US President Barack Obama's trip to Germany for the Hanover Trade Fair in 2016 (Fig. 2).

A Few Facts About Commercial Drones

Unmanned aerial vehicles (UAV) – alternately known as small drones, minidrones or micro UAVs – are remotely controlled from the ground, although higher-end models often additionally provide navigation technology so that they can independently fly predefined routes. UAVs are typically grouped into the following categories: drones for private use (toy and hobby), drones for commercial applications (aerial views, logistics, etc.) and drones for military applications (artificial targets, reconnaissance, combat). R&S®ARDRONIS is intended exclusively for commercial use. The rapid increase in the intelligence of commercial drones, (e.g. automated target recognition by logistic drones), the cost savings achieved through the use of drones in general and the intense interest from the private sector have all combined to cause the number of commercial drones to skyrocket exponentially. There are two basic types of drones: multicopters and fixed-wing drones. Fixed-wing drones are used in only limited numbers. Their greater range and altitude make them primarily suited to special tasks such as cartography and ground mapping. Reports in the media about drones almost always refer to multicopters. Additional criteria for the classification of drones include size, payload, speed, endurance, range, altitude – and the type of control. The last criterion is of particular interest for R&S®ARDRONIS, which is designed to detect the control signals.

Textual description of Fig. 1: Typical drone remote control systems, detailing proprietary FHSS/DHSS control systems, WLAN, and Bluetooth® technologies with their respective ranges and features.

Radio Technologies and R&S ARDRONIS Capabilities

Fig. 1 provides an overview of the various types of controls available on the market. More than 90% of all drones communicate over the commercially available industrial, science and medical (ISM) bands, which are also used for telecommunications, e.g. for WLAN and Bluetooth® radio systems. The 2.4 GHz and 5.8 GHz bands see the most use, while use of the 433 MHz band is rare.

By far the most commonly used (> 80%) radio technologies for remote drone control are proprietary implementations of frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS). In order to increase immunity to interference, both methods use a broader spectrum than is actually required to transmit the wanted signal. FHSS alternates the carrier frequency in a pseudorandom hopping sequence. The transmitter and receiver must be synchronized and use the same hopping algorithm in order to maintain the connection. In contrast, DSSS occupies a fixed, very large bandwidth, although it decreases the spectral power density to such an extent that the wanted signal is barely above the noise floor and can only be retrieved by using a precisely matching demodulator. The two methods, which are sometimes also used in combination, are perfect for the heavily used ISM bands, where many users and radio technologies must coexist. FHSS/DSSS is therefore considered to be a quasi-standard for drone control and is used by most manufacturers. However, the game of hide and seek being played with FHSS/DSSS radio links within the spectrum make them difficult to detect and disrupt. R&S®ARDRONIS is up to the challenge with its powerful online hopper analysis. It analyzes the technical radio parameters such as hop lengths, symbol rate and modulation type and is able to unerringly classify the transmission system, e.g. HOTT (Graupner), FASST (Futaba), M-Link (Multiplex) or DSMX (Spektrum) (Fig. 4).

Textual description of Fig. 2: Typical applications for drone monitoring and countermeasure systems: high-ranking events (for example, R&S®ARDRONIS guarded the G7 governmental heads in 2015 at Elmau Castle), test tracks for secret prototypes, critical infrastructures, sporting events, public rallies.

R&S ARDRONIS Key Features and Capabilities

Textual description of Fig. 3: R&S®ARDRONIS is a reliable, comprehensive system, featuring Situational awareness, Early warning, Detection, identification, direction finding/position fixing, Countermeasures, Signal disruption, Data recording, Open interface with an extendable drone library, Archival, and Postprocessing. The system is also Customizable and Interoperable.

Advantages of a Radiomonitoring Solution

The interception of drone control signals offers advantages over radar, optical, or acoustical detection methods.

• Reliable detection without false alarms: The system is not confused by other flying objects like birds, balloons, or kites.
• Earliest possible detection: R&S®ARDRONIS issues an alert as soon as a remote control unit begins transmitting, even before the drone takes off, allowing for prompt countermeasures.
• Direction finding / position fixing of drone operators: By detecting both the drone via downlink signals and the remote control unit via uplink signals, the system can immediately determine the bearing of the operator. With multiple direction finders, the operator's precise position can be fixed.

Situational Awareness and Signal Disruption

Situational awareness: R&S®ARDRONIS detects all drones over a large monitored area and can indicate the drone type via its radio signature, enabling threat assessment. Downlink activities, such as video transmissions, are also registered.

Signal disruption: The R&S®ARDRONIS system can be upgraded with a jammer to disrupt the radio link, forcing the drone into failsafe mode (landing or returning to origin). This jamming is selective and does not affect other radio activities. R&S®ARDRONIS creates radio parameter sets for detected drones, enabling timely intervention, such as automatic response to breaches of protected areas. The R&S®WSE follower jammer's speed handles rapid FHSS frequency hoppers.

Reliable Protection, Easy Operation

R&S®ARDRONIS utilizes antennas, direction finders, and signal analysis solutions from Rohde & Schwarz. These components, combined with a powerful detection algorithm, reliably intercept short-duration signals (as low as 350 microseconds), even in densely occupied ISM frequency bands. Optimal range is one to three kilometers, depending on drone and remote control transmit power and environment. Alerts can be linked to intrusions into protected areas to prevent false alarms. Technical parameters are compared against defined profiles, sorting drones into black list (threats), white list (own drones), and unnamed categories. A user-friendly operator interface displays detected drones and critical parameters (refer to Fig. 4). For R&S®ARDRONIS-D/P, direction finding beams or location markers show detection results on a map. An expert view provides detailed signal analysis for radio analysts (refer to Fig. 6).

Protected Area and Detection Range

Textual description of Fig. 5: R&S®ARDRONIS allows the definition of protected areas. If a drone enters a defined area, the remote control radio link is automatically disrupted.

Textual description of Fig. 6: The expert view offers detailed analysis of uplink and downlink signals of detected drones for radio experts.

System Components and Transportability

Textual description of Fig. 7: R&S®ARDRONIS consists of few components, making it easily transportable to different sites. The photo at the bottom shows R&S®ARDRONIS-D; others show R&S®ARDRONIS-I.

R&S ARDRONIS Configurations and Integration

Textual description of Fig. 8: R&S®ARDRONIS offers four configurations for various applications: R&S®ARDRONIS-I for detection in defined areas (e.g., stadiums, facilities), R&S®ARDRONIS-R for permanent monitoring and automatic countermeasures, and R&S®ARDRONIS-D or R&S®ARDRONIS-P for tracking and apprehending drone operators.

The system permits data recording of all detected results and RF scenarios. It is suitable for both stationary and mobile applications, with a turnkey, plug-and-play solution for easy transport (refer to Fig. 7).

Integrated Drone Monitoring and Countermeasure Systems

While R&S®ARDRONIS excels in early alerts, false alarm prevention, and perpetrator identification via radio signal interception, it has limitations with "mute" drones or those with fixed flight paths. For comprehensive protection, R&S®ARDRONIS can be integrated into systems with other components like radar, utilizing an open interface. The product is continuously updated with new functions, including profile database refreshes and planned cross-bearing fix capabilities.

Summary

The proliferation of commercial drones presents security challenges, from privacy invasion to endangerment and terrorism. Rohde & Schwarz's R&S®ARDRONIS provides early threat detection by intercepting radio links between remote controls and drones, identifying both the drone and pilot. Detection occurs upon remote control activation, enabling prompt countermeasures. Its open interface allows integration into broader drone defense systems, incorporating radar and other countermeasures.