Radio Frequency Modem Research Articles

Development of an unmanned airship for magnetic exploration

An unmanned airship was used to overcome the limitations of conventional aeromagnetic exploration systems. The airship was fabricated from non-magnetic fibre-reinforced plastic and urethane cloth, and filled with helium. The maximum payload is 10 kg and the flight time (with all equipment installed) is approximately 1 h. The airship is simple to move and store prior to gas injection, and easy to handle in the field because of its small size. An automatic flight algorithm enables stable and efficient exploration. A radiofrequency modem and long-term evolution router connect the airship to ground control even when it is not in the line of sight. Magnetic data and airship location are monitored in real time and verified using a helicopter. The airship showed high efficiency.

Wireless HROV Control with Compressed Visual Feedback Using Acoustic and RF Links

Underwater cooperative robotics offers the possibility to perform challenging intervention applications, such as recovering archeological objects as within the context of the MERBOTS research project, or grasping, transporting and assembly of big objects, using more than one mobile manipulator, as faced by the TWINBOT project. In order to enhance safety during the intervention, it is reasonable to avoid the umbilical, also giving more mobility to the robots, and enabling a broader set of cooperative movements. Several solutions, based on acoustic, radiofrequency (RF) or Visual Light Communication (VLC) have been proposed for underwater communications in the literature. This paper presents the architecture of an underwater wireless communication framework for the control of multiple semi-autonomous robots in cooperative interventions. The proposed framework is composed of several modules as the virtual reality interface using UWSim, the Underwater Multi-robot Cooperative Intervention Remote Control Protocol (UMCI-RCP) and a Generic Link Layer (GLL). UMCI-RCP allows the control of an underwater robot over limited communication links. UMCI-RCP integrates a progressive compression algorithm that provides visual feedback at a constant rate and ensures image reception even in channels with loses. The Time Division Multiple Access (TDMA) medium access strategy minimizes the jitter of transmitted packets. The GLL has been designed in order to provide support for multimodal transmission (i.e. acoustic, RF and VLC) and also to interface with the UWSim-NET simulator so that facilitates the experimentation either with a real or with a simulated modem. The possibility of exchange real and simulated devices in the proposed framework are demonstrated by means of a teleoperation experiment with a BlueROV equipped with the S100 RF modems. Hardware-In-the-Loop (HIL) capabilities are demonstrated repeating the experiment with the real modems and modeling the BlueROV, and also modeling both the modems and the BlueROV.

Implementation of a low cost, solar charged RF modem for underwater wireless sensor networks

Abstract Underwater communication (UWC) has become an attractive research field over the past few decades. This is mainly due to the increase in underwater applications such as exploration, monitoring, and warning systems. Traditional communications techniques face many obstacles when used underwater. Optical communications require line of sight which is not always maintained underwater due to turbulence. Acoustic communication does not suffer from that, however, it can only operate with very low rates. While radio frequency (RF) communication can only operate over short distances due to the attenuation from the water, it can deliver relatively high data rates and does not require line of sight nor affected by turbulence. Additionally, it does not suffer much when crossing the air–water boundaries. Moreover, underwater nodes require a new method of powering as it is not feasible to change their batteries when they are depleted. And so, we have investigated underwater solar power harvesters as a means to power the underwater nodes. In this paper, we design, implement, integrate, and test a low cost solar powered RF underwater modem to be used as a building block of an underwater wireless sensor network. The system was tested with multiple nodes to allow multi-hop communications in order to increase the communication distance. Results show that the network operates with a moderate to high throughput from end to end.

Remote control‐based energy management for energy savings in a central heating system

In this study, to enhance the performance of a central heating system, the following tasks were performed on the system via Radio Frequency modems: collection of data, evaluation of the system, real time monitoring, remote control, and management processes. A central heating system testing apparatus and related software and hardware were developed. Both short‐time and long‐time experiments were conducted. In the experiments, Case 1, in which the system operated under ambient conditions for an hour without remote control, was compared with Case 2, in which the space temperature was kept constant at 21°C. The experimental results indicated that Case 2, in which remote control‐based energy management was conducted, resulted in 20 L of fuel savings compared to Case 1, and a 57–60% thermal efficiency was measured. As a result, a central heating system using remote control‐based energy management is more efficient, economical, and less harmful to the environment. © 2016 American Institute of Chemical Engineers Environ Prog, 36: 600–609, 2017

Development of Open source-based automatic shooting and processing UAV imagery for Orthoimage Using Smart Camera UAV

Abstract. Recently, aerial photography with unmanned aerial vehicle (UAV) system uses UAV and remote controls through connections of ground control system using bandwidth of about 430 MHz radio Frequency (RF) modem. However, as mentioned earlier, existing method of using RF modem has limitations in long distance communication. The Smart Camera equipments’s LTE (long-term evolution), Bluetooth, and Wi-Fi to implement UAV that uses developed UAV communication module system carried out the close aerial photogrammetry with the automatic shooting. Automatic shooting system is an image capturing device for the drones in the area’s that needs image capturing and software for loading a smart camera and managing it. This system is composed of automatic shooting using the sensor of smart camera and shooting catalog management which manages filmed images and information. Processing UAV imagery module used Open Drone Map. This study examined the feasibility of using the Smart Camera as the payload for a photogrammetric UAV system. The open soure tools used for generating Android, OpenCV (Open Computer Vision), RTKLIB, Open Drone Map.

Development of Open source-based automatic shooting and processing UAV imagery for Orthoimage Using Smart Camera UAV

Recently, aerial photography with unmanned aerial vehicle (UAV) system uses UAV and remote controls through connections of ground control system using bandwidth of about 430 MHz radio Frequency (RF) modem. However, as mentioned earlier, existing method of using RF modem has limitations in long distance communication. The Smart Camera equipments’s LTE (long-term evolution), Bluetooth, and Wi-Fi to implement UAV that uses developed UAV communication module system carried out the close aerial photogrammetry with the automatic shooting. Automatic shooting system is an image capturing device for the drones in the area’s that needs image capturing and software for loading a smart camera and managing it. This system is composed of automatic shooting using the sensor of smart camera and shooting catalog management which manages filmed images and information. Processing UAV imagery module used Open Drone Map. This study examined the feasibility of using the Smart Camera as the payload for a photogrammetric UAV system. The open soure tools used for generating Android, OpenCV (Open Computer Vision), RTKLIB, Open Drone Map.

수중-육상 네트워크 연계용 게이트웨이 부이시스템 개발 및 실 해역 성능 검증

게이트웨이 부이시스템은 수중 어플리케이션 구현 시 수중-육상 간 네트워크 연계를 위한 시스템으로 수중노드와 육상국간 통신 연계, 수중 네트워크 모니터링 등을 수행한다. 본 논문에서는 다수의 수중노드로 수중 네트워크를 구현 시 취득된 데이터들을 육상국과 연계하여 실시간으로 모니터링이 가능한 게이트웨이 부이시스템 개발에 대해 소개한다. 개발된 게이트웨이 부이시스템은 수중음향통신모뎀, RF 통신시스템, 게이트웨이 운용시스템으로 구성되며, 게이트웨이 운용과 수중 네트워크 상태모니터링을 위한 육상국용 관제 프로그램을 구현하였다. 또한 실 해역 시험을 통해 실시간 수중 네트워크 모니터링, 게이트웨이 상태모니터링 등의 성능 검증을 수행하였다. A gateway buoy system connects a underwater network to a terrestrial network, which enables to efficiently monitor the underwater network on a land station. In this paper, we introduce an implemented gateway buoy system which relays gathered data from multiple underwater nodes to a land station in a real time. The gateway buoy hardware system is composed of a underwater acoustic modem system, a radio frequency modem system, and a gateway operating system. in additional, we have implemented a land operating program and a land monitoring program for gateway system and states of underwater network, respectively. We also perform real-sea experiments to verify the performance of the gateway buoy system which real-time monitors underwater network states and gateway system states.

동축반전 헬리콥터형 소형 무인항공기 설계 및 제작

The rotorcraft-based unmanned aerial vehicle(UAV) capable of performing close-range surveillance and reconnaissance has been developed. Trade studies on mission feasibility led to the adoption of a coaxial rotorcraft with twin rotors counter-rotating in one axis and driven by electric motors. A commercial off-the-shelf flight control computer(FCC) and a radio frequency modem were adopted for autonomous navigation. In order to achieve an aerial view, commercial charge-coupled device camera was also integrated into the vehicle. The performance of the completed vehicle was proved with manual flight test, and mission capability was verified through waypoint navigation flight after being equipped with FCC. This paper treats the whole process of design and system integration for development of the coaxial rotorcraft UAV.

City hazardous gas monitoring network

In our today's societies, many dangerous chemicals are produced and transported. Due to the vast use of chemicals, more chemical accidents are taking place with huge losses. In this study a city hazardous gas monitoring network was designed to detect the dispersion of toxic and combustible gases in the primary stages. The network could cover hazardous chemical facilities, important hazardous chemical routes, warehouses and special locations which may be the targets of terrorist attacks. The network is consisted of several local networks and a central control panel complex. Each local network has a local control panel in the center and many detectors and sounders around it at distances less than 3000 m that communicate with the local control panels wirelessly. In each location there are two types of gas detectors, toxic and combustible, and a sounder which are equipped with a wireless, radio frequency modem allowing the units to communicate readings and other information on a real-time basis with a remotely located local control panel. High sensitive Photo Ionization Detectors, PIDs, are used to provide fast and low-level on-site screening for chemicals contamination. Combustible gas detectors are the second choice to sense the combustible gas and verify the readings of PIDs in this regard. The central panel consists of several connected control panels work uniquely helping a computer set and the appropriate software and communicate with local control panels via telephone lines. All of the network components are shown on the monitor of central panel with special symbols by geographical information system program. The system is fully addressable so that the high level detection of a detector produces a blinking color double-circle around its symbol in GIS plan. In case of high level gas detection, a team of experts who are fully equipped with different portable detectors depart to the site to test the field to identify the chemicals. All readings of detectors are saved in a data bank and then analyzed to find any chemicals spills and leakages. The network was simulated by a special program so that the components of local networks and the central panel are shown in separate windows. By clicking on one detector on environmental window the formerly designed responses will be activated in central panel window.

A Wireless Network for Collection and Synthesis of Mobile Mesoscale Weather Observations

Abstract This paper reports the development of a wireless network of instrumented vehicles and aircraft for the real-time collection and synthesis of their mobile weather observations in mesoscale field experiments. The mobile digital network (MDN) utilizes 900-MHz radio frequency modem technology, enabling real-time data transmissions at up to 115 kbit s−1 across a domain of about 40 km on a side. The effective throughput of the network of multiple mobile units is about 40 kbit s−1 due to overhead from data quality checking and acknowledgment that data have been received. After gathering data from mobile observing platforms at a centrally located mobile command post, both image products and data are then uplinked via geostationary satellite at about 80 kbit s−1 and served to the Internet. The first application of the MDN was to mobile field observations obtained during the International H2O Project (IHOP).

MODIFIED CENTER PIVOT SYSTEM FOR PRECISION MANAGEMENT OF WATER AND NUTRIENTS

Spatial yields since 1985 in a corn-wheat-soybean rotation at Florence, S.C., show little correlation of yielddata with expected yields for soil map units. Research suggests that spatial yield variability for the southeastern CoastalPlain may be caused primarily by water relations. This causes difficulties in scheduling irrigation for conventional centerpivot irrigation systems, which are not capable of applying variable depths of water to small areas of variation within thetotal system. Thus, the objectives of this work were to design and construct a site-specific center pivot irrigation systemthat could independently apply variable rates of water and chemicals to 100-m2 areas within the irrigation system. Acommercial center pivot system was modified by adding three 9.1-m manifolds in each of 13 segments along the truss.Nozzles were spaced 1.5 m apart along each manifold, and both manifolds and nozzles were sized to provide 1x, 2x, and4x nominal application rate at a given tower speed. All combinations of the three manifolds provided up to 7x nominaldepth, which was 12.7 mm, in 1.8-mm increments when the outer tower traveled at 50% of full speed. A programmable,computer-controlled management system was installed near the pivot on the moving portion of the center pivot system.This controller obtained the position from the center pivot controller via a radio frequency modem and switched on theappropriate valves to obtain the application rate for a specific area. During 1995 and 1996, the system applied water andN fertilizer in a fixed-boundary field experiment. Measurements and observations of water and N application uniformitieswere acceptable; however, more extensive evaluation will be required before definitive conclusions can be reachedregarding N application. Surface temperatures measured with an integral infrared thermometer system producedencouraging results that may be useful in management of water and nutrients. Using experience gained with this system,a second commercial center pivot system is being modified for site-specific water, nutrient, and pesticide management ona field with soil variation (irregular boundaries) typical of the Coastal Plain.

Transmission for digital video signals coded by CCITT H.261 on a private broadband LAN using co-axial cable

The development of a new multi-media network system for transmitting multi-channel video, audio, digital control signals and other signals on a co-axial cable gives new possibilities for the transmission of digital video signals coded by CCITT H.261. All these signals can be transmitted at the same time using frequency division multiplexing. The paper describes the development of a QPSK (quadrature phase shift keying) transmitter and receiver, and RF (radio frequency) modems which use this system. It is especially concerned with the new QPSK transmitter's and receiver's capability to transmit digital video signals coded by CCITT H.261 either individually or combined with the other signals above. Digital video signals are modulated by QPSK. The QPSK transmitter has a maximum digital data transmission rate of 1O Mbps and transmits digital video signals at the standard rate of 1.5 Mbps. Furthermore it describes new bi-directional multi-channel RF modems for general purposes. Digital control signals are modulated by frequency shift keying. The modem has a maximum digital data transmission rate of 128 kbps.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>