I. FOREWORD
On the base of our more than 50 years’ experience we are developing a broad range of products and Systems against many kinds of threats on air, land and water. Our last developments in the field of: underwater and surface control of our Systems with own innovative technologies for hydroacoustic, radio and satellite communications; increasing the detection distance of our sensors and the sustainable transfer of the necessary information to the operators and the response forces; identification, verification and to counteract against drones provide us with confidence that we are able to solve any problem in many areas connected to the security and protection of Critical Infrastructures (CI).
Our teams are made up of highly qualified specialists in the fields of Material Science, IT, Radio Communications and Engineering Ammunition Development.
Our Systems and products are highly efficient, reliable, “user friendly”, easy to operate and maintain, high cost effectiveness and efficiency; they can be very easily to be integrated in the existing Systems for Security and Protection of CI. They are open Systems that can be upgraded with new modules and capabilities.
We provide support for our Systems 7/24/365 with the help of our local partners.
Our Company Management System is certified in connection with ISO 9001:2015 requirements.
We are a member of the Bulgarian Defence Industry Association and on this basis and in this connection we are a member of the AeroSpace and Defence Industries Association of Europe.
On the base of above mentioned, there are many partnerships we have established with a number of international clients in the course of joint implementation of large and complex projects.

II. INTRODUCTION
We have developed very complex System against drones – “ADD-400-1”. The System takes into account all aspects, all phases of securing and protecting Critical Infrastructures against enemy drone attacks (identification, verification, violation of the drone flight plan and / or destruction thereof).
Our System is a member of the third family of Anti-drone Systems – Optics/electro-optics (EO) and thermal.
Optics/EO and thermal are common parts of drone detection Systems. Through the cameras we use and our software developed, with the fullest extent overcome the negative effect of combining the angle / range of the cameras and the distance to identify and verify the drones entering the security area (it’s common knowledge that camera and thermal performance is a trade-off between FOV (field of view) and distance – the greater the angle that is being monitored, the less distance).
The main focus of our System is directed to the NATO UAS Classification – micro and mini drones.

III. ADVANTAGES OF “ADD-400-1”
1. Multifunctionality – depending on the specific environment and the customer needs, the System can operate in the following modes:

• manual – all operations are managed by an operator from the Command Center;
• semi-automatic – operator intervention is carried out for a limited number of functionalities – for example, control of the end devices (jammer, active bodies for protection), etc.
• automatic – after the System is deployed and it is ready for operation, the System fulfills its full functionality without human intervention.

2. Continuity – the System has the ability to operate in 24/7/365 mode, automatically switching from day to night mode.
3. Versatility – the System is designed to combat all types of micro and mini drones, regardless of flight mode – operator control or flight in silent mode.
4. Complex solution – complete hardware and software support for detection and counteraction (until destruction) of the threat.
5. High degree of protection against the effects of adverse environmental factors – rain, sand, etc.
6. Quick deployment and easy operation of the System – the trained team deploys the System and prepares it for work within 10 minutes.
7. Development opportunities. The modular type of the System allows its continuous improvement and expansion both in the hardware direction (with new types of sensors and terminal devices), as well as with the improvement of the application software and acquisition of new capabilities.
8. The basic version of the System is highly cost effective and efficient because it provides a very good level of identification and counteraction without burdening the System with additional modules such as radars or acoustic sensors.
9. The System can be very easily to be integrated in the existing Systems for Security and Protection of CI. As it was mentioned above, the System is “open” mode and it can be integrated in every existing systems for security and protection.

IV. ANTI-DRONE SYSTEM “АDD-400-1” – DESCRIPTION, MAIN FUNCTIONS
4.1. Purpose
The Anti-drone System “ADD-400-1” (System for counteraction to unmanned aerial vehicles) is designed to:

• disrupt the functions of the GPS navigation and control systems of low flying unmanned aerial vehicles (UAVs);
• destroy low flying UAVs

The System can be used individually or in groups, providing a safe area, primary used for:

• protection of military and civil infrastructure from intelligence, targeting and deployment of enemy forces and assets through UAVs;
• protection of military and civil infrastructure against terrorist attacks through UAVs.

4.2. Function
The System is activated by a combined sensors. It cannot be activated by random noises – moving clouds, birds, far fighting airplanes, etc.
The system operator can counteract the drones by selecting a Jammer or Remote Controlled Warheads.
The Control System of the fuse processes and analyses the signals from the sensors and activates the Remote Controlled Warheads in case a drone enters in its hitting range, or deactivates it on expiration of the preset operation time.
The modes for neutralization or self-destruction of the warheads on expiration of the operation time can be selected and are field programmable. The device is also provided with an anti-removal feature.
The warheads can be activated/desactivated or neutralized or detonated through radio remote control from the Command Unit.

4.3. Configuration
The Anti-drone System “ADD-400-1” consists of the following functional units:
4.2.1. Optical-electronic sensor unit (OESU) consisting of:

• specialized calculator with control unit and radio-communication block;
• day and night sensors;
• rain and light sensors.

OESU (Fig.1) is mounted on a telescopic stand and serves for detecting, recognizing and tracking UAVs, and for sending signals for activating the devices for counteraction to the UAVs.

4.2.2. Jammer
The Jammer (Fig.2) is mounted on a telescopic stand and serves for creating interruptions within the frequency ranges L1, L2, L5 and the signals for control and data exchange of UAVs at frequency of 2.4 GHz and 5.8 GHz.
The jammer consists of:

• electronic block;
• antennas – 5 pcs.;
• electro-supply block.

4.2.3. Remote Controlled Warheads-Remotely Controlled Charges RCCh -100
The main purposes of these devices is destroying low flying UAVs.
The RCCh-100 consist of (see Fig.3 – Fig.4):

• A warhead with handles and a coupling for connecting cable line, detonating cord or NONEL shock tube detonator;
• A retractable stand;
• An aiming device (red dot);
• The stand is attached to the ground using special pegs and a hammer.

4.2.4. Transceiver/ Group ignition radio module
The Transceiver is placed in an airtight plastic briefcase and is used for remote control of up to 4 pcs. active bodies for destruction.
The Transceiver consists of:

• microcontroller;
• radio-modem;
• supply block.

4.2.5. Command and Control Center
The Command and Control Center (CCC) is housed in a plastic case and serves to control and monitor the “ADD-400-1”’s elements.
CCC (Fig.5) consists of:

• processor with display and keyboard;
• radio-modem;
• supply block.

The Command and Control Center includes three program modules:
1. IMS_Dron_ProgramingV1P.exe – used to define the work / controlled / area geocard. Works in an environment with an active internet connection.
2. IMS_DronCenterAdminV1P.exe – binds / disposes / to the geocard in OFF Line mode used devices.

3. IMS_DronCenterOperatorV2P.exe – The program is used for operational management of the devices in the system in group or individually. The program has a limited set of commands as it is intended for Operator operation.

4.3. Main Tactical and Technical Characteristics of “ADD-400-1”

Table: Main Characteristics and Parameters of “ADD-400-1”

4.4. Functionality
The device can function autonomously or be controlled by an operator through the command center.
When the sensor block detects a UAV flying over the area of destruction of the active means, a decision is made to fire or to activate the manner. The jammer and active mean can be activated automatically or at the command from the control center.
The “ADD-400” is protected from interferences caused by clouds, birds, rain, sand, far flying aircraft and more. It has the ability to be activated/deactivated or neutralized by a pre-set program or through a command from the CC.
The “ADD-400” has a module architecture of open type, allowing different device configuration options to be selected depending on specific requirements, such as:
Variant 1: Optical-electronic sensor and jammer;
Variant 2: Variant 1 plus radar;
Variant 3: Variant 1 or 2 with different number of active means for destruction;
Variant 4: Variants 1 to 3, with the command center being moved to a fixed point with additional screens, etc.