International Conference on Information and Communication Technology and Its Applications (ICTA 2016) Federal University of Technology, Minna, Nigeria November 28 – 30, 2016 Development of a Helical and Pigtail-Based Range Extension System for Campus Surveilance Quadcopter M. Saidu, Elizabeth N. Onwuka, A. M. Aibinu, H. Bello Salau, F.O. Saliu, X. Shemang, and M. N. Mohammed Federal University of Technology, Minna, Nigeria samuslim@futminna.edu.ng, onwukaliz@futminna.edu.ng, maibinu@gmail.com, habeeb.salau@futminna.edu.ng Abstract—A Quadcopter commonly known as a drone is a type transmits videos and photographs captured to the LCD of Unmanned Aerial Vehicle (UAV) that is lifted and propelled screen receiver at the ground control station. by four (4) rotors. They usually come with a control pad and One of the serious challenges of any UAV, especially in LCD screen receiver that receives videos and photographs surveillance applications, is the short communication range from the quadcopter while aloft. The major problem faced by between the Quadcopter (transmitter) and the LCD screen UAVs is the communication range limitation between the (receiver). The longer the communication range between drone and its ground control station. Generally, the longer the devices and their controls, the more efficient the output and range, the larger the UAV coverage, and in turn, the more also more conveniently they can be remotely operated [3]. productive. In this work, a range extender system was This challenge can be overcome by a variety of techniques, constructed and used to extend the communication and control range of a campus surveillance drone. To achieve this, the which include the use of a Wi-Fi repeater, and increment of quadcopter was coupled and many field trials were conducted the strength of the transmitter antenna among others. Wi-Fi for the purpose of understanding its flight mechanism and to repeater, which could also be called a wireless range empirically measure its range. However the average extender/booster, is a wireless repeater that extracts signal communications range between the quadcopter and its control that already exist from a wireless router and rebroadcasts it pad was 108 meters. In order to increase this range, range to create a second network. On the other hand an antenna is extender system was constructed. It consists of a pigtail an electrical device that converts electric power to radio antenna for extending the control and video transmission waves and coverts radio waves back to electrical power. range, and a helical motorized antenna for extension of the Helical antenna is a passive radio frequency signal booster flight range. Flight trails and empirical measurements at the that uses the principle of convergence of RF signals at the Federal University of Technology Minna campus showed that focal point of reflective parabolic object, which increases the the communication range of the UAV was extended by 200 transmission and reception signal range. Pigtail antenna meters. usually has a high frequency coupling device called PIGTAIL that enables the antenna to be mounted to the Keywords-surveillance quadcopter; communication range; circuit [4]. control station; pigtail antenna, helical antenna, range extender. In this work, we used both helical and pigtail antennas to extend the communication range between the quadcopter and I. INTRODUCTION its control pad at the ground station. Firstly, various parts of the quadcopter were coupled together and tested several An Unmanned Aerial Vehicle (UAV), known commonly times in the field to understand its principle of operation and as a drone is an airplane without a human pilot on board. Its also to determine its maximum average communication flight is controlled either autonomously by computers in the range. The antenna inside the control pad and the LCD vehicle, or under the remote control of a pilot on ground or screen of the quadcopter were then extended using a pigtail in another vehicle [1]. The vehicles are developed purposely antenna. Helical antenna was also constructed and the cable to operate in regions where the presence of an on-board from the antenna was then connected to the pigtail antennas human pilots is either unnecessary or too dangerous. UAVs on the control pad and the LCD with the aid of connectors. have prospective applications in military for recognition, The rest of the paper is organized as follows: Literature environmental observation, and maritime surveillance. Other review is presented in section 2. Methodology of the work is non-military applications of UAVs are environmental and described in section 3. Test and Result is presented in infrastructure surveillance among others [2]. A quadcopter is section 4, while, section 5 concludes the paper. a type of UAV with four (4) rotors which pushes air downwards, thus, creating a thrust force keeping the vehicle on air. It usually has a control pad with LCD screen which is II. LITERATURE REVIEW used to control its speed, direction, and flip motion. The In recent years, development of UAVs has become a LCD screen receiver receives aerial videos and photographs significant growing segment of global aviation industry. which were taken by the camera mounted on the Quadcopter. These vehicles are purposely developed to operate in various This camera has a pigtail antenna mounted on it which applications where human intervention is dangerous or 227 International Conference on Information and Communication Technology and Its Applications (ICTA 2016) considered difficult [3]. The first flying quadcopter was terminal of the antenna. The energy from the current invented by Etienne Oehmichen in 1922 in order to run supplied by the radio transmitter is radiated as “Wireless Control Quadcopter with Stereo Camera and Self electromagnetic waves/radio waves by the antenna and Balancing System” research. Several theory and techniques during reception, an antenna intercepts some of the power of were reviewed from previous related research report. The an electromagnetic wave thereby produce a tiny voltage at its reviews includes the technological development and control terminals. This voltage produced at the terminal of the methods used in the development of the quadcopter. The intercepting antenna is applied to a receiver to amplify it. inputs are usually the desired values of the height, roll, pitch Antennas can be used for a large variety of equipment that and yaw. While the outputs are the power of each of the four uses radio such as radio broadcasting, television rotors that is necessary to reach the specifications. The first broadcasting, telephones, radar, communications receivers, recorded construction of a quadcopter was in the same year satellite communications, wireless microphones, and when Georges De Bothezat and Ivan Jerome fabricated and Bluetooth enabled devices among others. [7][8] flew the Quadcopter. The quadcopter was to a certain extent The focus of this work is extension of communication large and used variable-pitch propellers for control. This and flight range of a campus surveillance UAV. A range project sponsored by the United State army was cancelled extension system consisting of pigtail antennas, and when the quadcopter proved difficult to fly and the military motorized helical antennas was developed to achieve this became more interested in autogiros. Later in 1956, another purpose. The methodology used in doing this is discussed in more successful quadcopter was built and flown by designer the next section. D. H. Kaplan [4][5]. Quadcopter exists in different sizes ranging from as small as size of a compact disc (CD) up to something big as one III. METHODOLOGY (1) meter in width. Larger quadcopters need larger motors which, in turn, have larger inertias and cannot be controlled The methodology employed in this work is in three fold, as quickly as smaller motors. As the size increases to a which is described in three (3) subsections, which are; certain level, the quadcopter can no longer be stabilized coupling of the quadcopter parts, extension of the UAV through RPM control alone because the torque required to control and video transmission range with pigtail antennas quickly change the rotational velocity of the motor exceeds and the construction of the motorized helical antenna for the capacity of the motor. Therefore, variable-pitch blades extension of the UAV flight range. become essential for larger quadcopters merely for stabilization purposes The longer the communication range between devices A. Coupling of the Quadcopter Parts. and their controls, the more efficient the output and also the The drone used in this work came as experimental more conveniently it can be remotely operated. The chassis parts, which were then assembled together to give a communication range between quadcopter and its control complete quadcopter system. The snap-shot of the assembled pad could be extended through the use of Wi-Fi repeater and system is shown in plate 1. These parts include camera, increment of the length of the transmitter antenna [6]. A Wi- propeller guide, propeller and Quadcopter stand among Fi repeater which could also be called a wireless range others. The control pad and LCD screen constituted the extender or wireless range booster is a wireless repeater that control system at the ground station. The assembled system extracts signal that already exists from a wireless router and was taken to the field and tested several times with the aim rebroadcasts it to create a second network. When two or of understudying the principle of its flight operation and also more hosts have to be connected with one another and the to understand the control mechanism. The maximum distance is too long for a direct connection to be established, average communication range between the quadcopter and a wireless repeater is used to bridge the gap. Wi-Fi repeater its control system at the ground station was also determined has been used to extend the range of communication between empirically during these fields. the quadcopter and its control station by taking a signal that already exists and rebroadcasting that same signal thereby creating a second network. [6]. Radio repeater is a type of wireless repeater used to B. Extension of the UAV Control and Video Transmission extend the range of coverage of a radio signal. It usually Range with Pigtail Antenna. consists of a radio receiver connected to a radio transmitter. In other to extend the communication range between the The received signal is amplified and retransmitted, often on quadcopter and its control pad, the length of the antenna in another frequency to provide coverage beyond the initial both the control pad and LCD screen pad of the system were range, without any alteration to the signal. increased. We opened both the control board and the LCD An antenna or an aerial is an electrical device that screen and soldered 2cm of a 2.4 GHz Pigtail antenna to the converts electric power to radio waves and from radio waves length of the antennas found inside the two components. back to electrical power. Radio waves are electromagnetic waves which carry signals at the speed of light through the This antenna is described as pigtail because it has a high air or space with almost no transmission loss before getting frequency coupling device called PIGTAIL, which enabled to its destination (the receiver). They are commonly used us to mount the antenna to the circuit. The end of the pigtail with radio transmitters and radio receiver. In order to antenna in both the LCD screen and the control pad were transmit signal using an antenna, a radio transmitter supplies connected to a female connector, the snapshot of this an electric current oscillating at radio frequency (RF) to the connection is shown in plate 2 and 3 respectively. 228 International Conference on Information and Communication Technology and Its Applications (ICTA 2016) C. Construction of the Helical Antenna for extension of the UAV Flight Range. A helical antenna is a spring with N turns made up of a conducting wire wound in the form of a helix with a reflector. Helix dimensions is determined by the wavelength (λ) which also depend on the frequency (F) of the radio wave used as shown in the following equations. λ = 0.3/Ϝ ………………………………. (1) D = λ/π ………………………………… (2) C = Dπ …………………………………. (3) d = C/4 ……………………………….... (4) Where „F‟ is the operating frequency (2.4 GHz), D is the Plate 1. The assembled Quadcopter diameter of a turn, „C‟ is the circumference of a turn and„d‟ is the approximated space distance between the turns. To obtain a circular polarization around the axis, the circumference (C) of a turn must be approximately one wavelength (λ) and size of the reflector (R) is equal to C or λ.[11][12] The materials we used in the construction of the helical antenna based on the values obtained from the equations are shown in plate 4. Two 40 cm PVC pipes were used and the wires of a coaxial cable were wounded around the pipes making use of 12 numbers of turns at a distance of 3.3cm to produce the helical antenna. The wire has a colorized PVC isolation and the slight difference in D of 42 mm as against the calculated 39.3 mmisdue to the thickness of the isolation. The calculated 132 mm of C obtained is 1.07 of λ. The two helical antennas constructed were placed on an RC reflector which was curved in order to focus the energy in one direction.The Helical antenna was then placed on a Dual axis motorized stand, which is connected to a gear box used in controlling the direction of the Dual axis motorized stand. The stand is powered by a 12 V D.C battery by connecting Plate 2. Pigtail antenna on the control board the cable from both motors on the stand to it. The snapshot of the constructed helical antenna on dual axis motorized stand is shown in plate 5, while, the snapshot of the entire UAV extender system is shown in plate 6. This antenna extends the flight range of the quadcopter in a given direction. Plate 3. Pigtail antenna on LCD screen receiver. Plate 4. Materials for Helical Antenna 229 International Conference on Information and Communication Technology and Its Applications (ICTA 2016) Plate 5. The helical antenna mounted on the Dual axis motorized stand Plate 7a. FUT Minna, Senate Building Road Plate 6. UAV extender system Plate 7b. FUT Minna, Research Farm IV. RESULT AND DISCUSSION The complete project work shown in plate 6 was taken to a field in campus for test and evaluation. The quadcopter crash landed several times at the early stage of the test. However, after several trails, all the commands sent to the quadcopter from control pad, such as flipping, trimming, hopping, taking aerial video and photographs were well executed. Since the flight extender is a directional antenna, while the Quadcopter is on flight, the helical antenna points in the direction in which it flies by using the buttons on the gear box connected to the antenna to control the Dual axis motorized stand in the up or down, left or right directions. Plates 7 (a), (b), (c) and (d) show some of the aerial photographs taken by the quadcopter while aloft in campus. Plate 7c. FUT Minna, Academic Publishing Center 230 International Conference on Information and Communication Technology and Its Applications (ICTA 2016) flight range of the UAVquadcopter. Field tests with the developed system at the Federal University of Technology (FUT) Minna air space showed that the communication range was successfully extended by 200 meters. This means that the new communication range was measured to be averagely 308 meters line of sight. The vehicle was therefore able to gain wider coverage aloft and videoed and transmitted very clear aerial images of the areas covered. This shows that campus surveillance can be better achieved with the UAV. However, considering the size of this campus, multiple UAVs may be employed for complete surveillance. REFERENCES [1] Barnes, O. “ The Wider Context; Royal Air Force Directorate of Defense Studies” 2009. U.S.A. [2] Hung, J. Y. and Gonzalez, L. F “Design, Simulation and Analysis of Figure 1. Plate 7d. 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