Radio Buoy Research Articles

ЕКОЛОГІЧНО БЕЗПЕЧНА ЗАГОРИЗОНТНА РЛС МЕТРОВОГО ДІАПАЗОНУ ДЛЯ ОХОРОНИ ТЕРИТОРІАЛЬНИХ ВОД

Subject and Purpose.Without regard to successes attained in the field of monitoring of territorial formations frontier areas and environment the problem of territorial waters guard and control of economic zone is as well as before actual for many states, that have the prolonged marine boundary. The aim of researches is an improvement of method of ecologically safe exposure of surface objects beyond the radiohorizon and development of ecologically safe meter wavelength radar for the guard of territorial waters with the use of active floating radio buoy. Methods and Methodology.Taking into account ecological requirements to the radiotechnical equipment and feature of beyond the horizon radio wave propagation the bistatic radar for surface objects exposure beyond the radiohorizon was proposed. One of the system features is the use of active radio buoy located on considerable distance from a shoreline. To estimate the system operationthe methods of analysis and numerical modelling are used. Results. Having conducted the analysis of basic mechanisms of radio wave propagation beyond the radiohorizon and existed experimental data, the necessary power features of proposed meter wavelength bistatic radar is calculated. For practical realization of this system the algorithms for finding the distance to the surface object and its speed are brought in details. The functional diagrams for both coastal and radio buoy receivers are worked out. Detailed description of their operation is given. Conclusion. The ecologically safe impulsively-coherent radar system is proposed, its transmission device is set on radio buoy beyond the radiohorizon, The radar true coherence is obtained due to the use of continuous signal of driving generator transmitter, that is irradiated in a period between sounding impulses and after a reception and treatment in the receiver serves as a reference signal, the coherenceinterval exceeds the period of pulse-repetition considerably. The use of speed difference of surface objects to be located and wind waves that create radar clutter will allow to carry out the radar exposure of surface objects on a background of marine surface clutter.

ВИКОРИСТАННЯ РЕФЕРЕНТНИХ СТАНЦІЙ В НАВІГАЦІЇ

One of the most important instruments on a ship is the Global Navigation Satellite System (GNSS) receiver, which is designed to determine the ship's position. But these receivers, working with open source, determine the location of the vessel with an accuracy of (10 ... 15) m. In some situations, much greater accuracy is required. For this purpose, there were created stations that operate in differential mode, with their help you can determine the location of the vessel with an accuracy of 2-4 meters. Transmission of differential corrections from the base station to the consumer can be carried out using radio communication, satellite communication systems (for example, INMARSAT), as well as using digital data transmission technology RDS (Radio Data System) on the frequencies of FM radio stations. Currently, many countries already have a developed network of base (differential) stations, constantly broadcasting corrections to a certain territory. For example, in the USA, differential corrections are transmitted by the Coast Guard through marine radio buoys operating at frequencies (283.5...325.0) kHz. This research article analyzesthe influence of reference stations on the accuracy of determining the location during navigation. By comparing the known coordinates (obtained as a result of precision geodetic surveying) with the coordinates measured by the receiver and the calculated ranges, the basic navigation receiver forms corrections that are transmitted to consumers via communication channels. Combining several differential stations into a single computer system allows you to perform operations on the transportation of oversized cargo in restricted conditions (rivers, canals, ports, etc.), conducting hydrographic work with great accuracy. For water transport, the precise positioning system has many applications: dredging, prevention and analysis of accidents during the navigation in restricted areas, control of mooring of ships. Accurate navigation systems are technologies of the future. Their application is one of the main trends in the development of modern science and industry. Keywords: Global Navigation Satellite System, reference stations, differential mode, GNSS receiver, accuracy.

Mathematical modelling of construction of ship turning trajectory using autonomous bow thruster work and research of bow thruster control specifics

The article proposes a method of constructing the trajectory of a ship’s turn using a control device. Mathematical modelling of the turn trajectory is performed using MS Excel in conjunction with the MATLAB environment. To construct a trajectory, a conditional centre of turn will be used, it will be guided by a control device, such as a radio buoy, or a lighthouse with pre-known coordinates. The construction of this trajectory has two features: a step course change when rotated equal to a sector step, and the accuracy of the trajectory is achieved by using the Kalman filter, simplified to the amplification factor. The bow thruster moment is calculating using the bow thruster shoulder. The angular velocity of turning depends on the linear speed, therefore, the angular velocity can be adjusted not only by changing the bow thruster mode of operation, but also by changing the linear speed of the vessel. The article provides the program code for constructing a trajectory in the MATLAB environment, which takes its initial data from MS Excel. Therefore, the work forms the basic view of autonomous bow thruster control.

Development of Towed Radio Buoy for AUV

One way to extend the functionality of autonomous underwater vehicle is to use a surface buoy-repeater that provides a high-speed data exchange channel between the operator station and AUV in real time. Also, the data of the receiver of the satellite navigation system of the buoy make it possible to correct errors accumulated by the on-board navigation system of the device without using hydroacoustic navigation devices. The report presents the design stages of the towed radio buoy, its composition and functional diagram, structural appearance and some results of field tests.

Monitoring the gray whale sound exposure mitigation zone and estimating acoustic transmission during a 4-D seismic survey, Sakhalin Island, Russia

A seismic survey conducted in the proximity of the nearshore feeding grounds of gray whales Eschrichtius robustus off northeastern Sakhalin Island, Russia, required the develop- ment of a comprehensive monitoring and mitigation plan. Prior to the execution of the seismic survey, the sound levels from the airgun array source were modelled for all seismic acquisition lines. This yielded estimated shoreward boundaries for an assumed disturbance threshold of 156 dB re 1 µPa 2 -s sound exposure level (SEL) that allowed an assessment of which lines would require more stringent mitigation. To enable prediction of the sound front under variable propa- gation conditions, a set of acoustic footprints with a realistic range of parameters was pre-com- puted. In the field, an acoustic monitoring network of 9 bottom-deployed stations with tethered radio buoys transmitted full waveform data to a shore-based monitoring post. The signals were processed to yield pulse levels for comparison to the model predictions. The appropriate footprint was selected on the basis of the pulse levels received during the initial minute of a seismic line and communicated to observation teams. To further ensure the sustained accuracy of the selected foot- print during a line acquisition, the modelled levels were compared in real time to the measured readings as the source moved past the line of monitoring stations; they were consistently found to match the incoming received sound levels within an accepted tolerance of 3 dB. This selection approach resulted in the best available estimation of acoustic exposure even through significant temporal changes in the hydrological conditions.

Analysis of Flying Vehicle Cooperative Positioning by Sea-Surface Wireless Sensor Networks

Sea-surface wireless sensor networks (S2WSN) is a combination of many nodes forming a certain geometric shape, such as ships and sea-surface radio buoys. To satisfy the requirement of precise tracking for flying vehicle (FV) in times of exterior location datum outages, a cooperative positioning algorithm (CPA) for the FV is proposed. Time synchronization among the nodes is crucial to guarantee CPA. Taking a single-hop S2WSN as an example, the problem of low synchronization precision is resolved by two-way timing with unequal reply time (TWT-UTD). Monte Carlo simulation results show that, through optimizing the position dilution of precision among the sea-surface nodes and the FV, the absolute bias of the FV tracking by the proposed CPA is superior to that of the conventional single ship-based relative positioning method. Meanwhile, the synchronization precision is increased by more than 20% via TWT-UTD method.

원격탐지기능을 갖는 무선부표시스템

본 연구에서는 기존의 우선 부표가 지니고 있는 문제점들을 해결할 수 있는 원근해 어로용 고성능 무선 부표 시스템을 개발하였다. 2진 FSK 변조방식과 우선부표용 송수신 프로토콜을 도입하여 사용시간을 대폭 개선하였으며, GPS 위치정보와 여러 계측정보를 수집한 후 모선의 탐지기 호출이 있을 경우 전송함으로써 쉽게 탐색이 이루어질 수 있도록 하였다. 개발된 우선부표는 평균 73일의 동작시간과 120km 이상의 동작시간과 120km 이상의 동작범위를 갖으며, 분실과 도난을 방지할 수 있다. In this paper, high performance radio buoy system for inshore and deep sea fishery is proposed and implemented. Binary FSK modulation technique is used for real-time communication & control between buoys and buoy finder, and optimum access protocol is adopted for minimizing the power consumption of radio buoy system. Using the GPS and sensor techniques, location and environments of radio buoy can be accurately monitored and traced by the mother ship. Developed buoy system with 10 W transmitting power can cover over 120km coastal range and operate more than 73 days of battery life. Proposed digital coding methods can also assure high security from burglary and loss.

Sell Call Radio Buoy용 코드검출기 설계

Sell call radio buoy is mostly used for searching for the location of fishing nets. Sell call radio buoy for the detection of the code uses the band pass filter(BPF). All BPF is used by imported from Japanese companies. But, Japanese companies stopped selling buoys for searching for the location of fishing nets, and domestic manufacturing companies could not sell buoys any more. Therefore, In this paper, a new method to replace the conventional buoy code detector is proposed. The proposed methods are constructed with an analog filter division composed of BPFs and notch filters as well as a microprocessor with analog digital converters. The advantage of proposed methods is able to combine various codes, can enhance receiver sensitivity. The experimental results confirm the usefulness of the proposed method.

Spatial correlation of explosion-generated signals received by longitudinally separated hydrophones in the Mediterranean Sea

Results of an experiment carried out in the Mediterranean Sea on a propagation track ∼400 km in length are presented. The sources of sound were 2.5-kg trinitrotoluene charges. The signals were received by three hydrophones spatially separated along the track by distances of 100 and 300 m. The hydrophones were carried by radio buoys, which were connected with each other and with the receiving vessel. The frequency band under study was 240–340 Hz. Under the conditions of the experiment, the spatial correlation interval obtained with averaging over the spreading time of multipath signals proved to be smaller than 100 m. It was shown that the resolution of signals arriving over individual ray paths or in narrow ray bundles considerably increased this interval. In this case, its experimental value was found to exceed 300 m.

Spectral features of the water temperature and sound intensity variations measured on the shelf of the Sea of Japan

Results of a spectral analysis of the water temperature and sound intensity variations measured on stationary acoustic-hydrophysical tracks in the shelf zone of the Sea of Japan are presented. The measurements were carried out in different seasons with the use of equipment that included a vertical acoustic-hydrophysical measuring system, self-contained acoustic-hydrophysical radio buoys, and a self-contained electromagnetictype resonance (320 Hz) transmitter. Spectral features of temperature fluctuations caused by internal waves in a vertical water layer are studied, and their influence on the sound propagation is demonstrated on tracks of different lengths oriented along and across the shelf.

Channel characterization for high-frequency acoustic communications

Undersea internets or seawebs are currently being developed and tested for a variety of applications in which some kind of device (e.g., an ADCP, hydrophone, vertical line array, autonomous undersea vehicle) needs to pass information to another (e.g., radio buoy, surface ship). The underlying physical layer is often an acoustic modem. However, the ocean medium, though it can carry acoustic waves with remarkable fidelity to long distances, is also somewhat unreliable. Storms may cause network outages by both driving up the ambient noise and corrupting the clarity of the acoustic mirror formed by the air–sea interface. Meanwhile, as the SONAR community is well aware, the refractive effects of the ocean can lead to sweet spots and dead zones (shadows). The required sound output of a modem varies accordingly. We have been conducting a program (SignalEx) to: (1) better understand propagation in the high-frequency range (around 10 kHz), currently of greatest interest for modems; (2) understand how the environment degrades different modulation schemes; and (3) develop more robust schemes or select the appropriate scheme for the given conditions. This talk will summarize results from recent SignalEx sea tests.

Signal frequency instability of emergency radio buoys

Signal frequency instability of emergency radio buoys

Inertially released jettisonable airborne buoy

A radio buoy which can be jettisoned from an aircraft by a cable and which is intended to float on the surface of the ocean connected to a submerged hydrophone. During the drop a balloon is inflated by a forced intake of air through holes as a result of articulated openings in the form of scoops, the scoops unlocking by a bar the protective casing of the balloon and the safety device of the container, which is detached after impact with the water, the submerged container being linked with the electronics by a cable. The buoy can be used for underwater monitoring at depths up to 2,000 meters.

漁場における漂流船位の推定例について

An officer on duty on a fishing vessel watches the fishing gear drifting after setting a salmon gillnet or a tuna longline. At any time, if he can estimate his ship's position by any method concerning the gear without recourse to any object (flag, light, reflector, radio buoy), he can employ this method to watch the gear effectively. The authors experimented with the drifting of the Oshoro-Maru, a fishing training ship of Hokkaido University, and reported that the direction and distance of drifting could be estimated by the ship's head, condition and wind velocity. In our next study, accuracy of the estimated ship's positions was experienced according to this method, in the Bering Sea. The experiment 1. The drifting velocity and the direction having been calculated by previously reported equations [1], some drifting positions were estimated. 2. The ship's positions can be determined by the bearings and distances of the corner reflector connected to the gill-net. 3. The determined and estimated ship's positions checked every 30 minutes are shown in Fig.1. The accuracies of estimated positions 1. The daily distance errors (error of distance made good) related to the drifting time are shown in Fig.5. Furthermore standard deviations of distance errors are shown in Fig.6. 2. The differences of estimated drifting directions from the drifting direction in relation with the drifting time are shown in Fig.7. Standard deviations of direction errors are shown in Fig.8. 3. Under an ordinary condition a drifting time is 6 to 8 hours, the distance error is within 0.5n.m. (s.d.), and the direction error is about 5°(s.d.). According to this method, we could obtain satisfactory results from various angles for the sake of keeping watch over the fishing gear.

漂流特性による漁具監視法(日本航海学会第44回講演会)

An officer on duty on a fishing vessel was watching a drift net or long-line going a-drift after it had beeh set. Whenever, if he can estimate the relative position of the ship in relation to her fishing gear during drifting without recurring to an object (flag, light, reflector, radio buoy), he can employ the method to watch the gear effectively. For example, the authors made the experiment with the drifting of the Oshoro-Maru, a fishery training ship of Hokkaido University, in the Bering Sea, and tried to express the direction and distance of the drift by parameters with the ship's head and wind velocity.The experiment 1. The corner reflector connected to the drift net was selected as the datum point of the experiment. In this case, the reflector was allowed to drift together with the ship according to currents and waves, but it felt no effect from the wind in spite of the movement of the ship. 2. The observers on the ship measured the distance and the bearing of the reflector by radar every 30 minutes and calculated the drifting by solving the triangls. Observations were made several hours each day for 14 days. The results are as follows: 1. The relation between the wind velocity (W) and the drift is shown in Fig. 2. 2. The relation between drifting coefficient (K) and the ship's head (α) is shown in Fig. 3. Accordingly, the drifting velocity (U) is expressed by the following equation, U=(a-bα)√<S/Sw>W. 3 .The direction of drifting is closely related to the ship's head (shown in Fig. 8), accordingly, the drifting direction (β) is expressed by the following general equation, β=a+bα, and the coefficients a and b are based upon the ships' drifting characteristics. 4. Consequently, if one knows the drifting characteristics of his own ship, he can estimate the position to which the ship has drifted.

漁具監視における漂流船位の推定(日本航海学会第41回講演会)

An officer on duty on a fishing vessel watches the fishing gear drifting after setting the salmon gill-net or tuna longline. At any time, if he can estimate his ship's position by any method concerning the gear without recourse to an object (flag, light, reflector, radio buoy), he can employ the method to watch the gear effectively. The authors had experimented with the drifting of the Hokuseimaru (273 G/T), and reported that the direction and distance of drifting were estimated by the ship's head and wind velocity. And for the next study, we experimented on the accuracies of estimated ship's positions based on the method, in the North Pacific Ocean. The experiment 1. As the drifting velocity and directions had been calculated by previously reported equations, some drifting positions were estimated. 2. Ship's positions can be determined by the bearings and distances of the corner reflector connected to the gill-net (length 3n.m., depth 7m). 3. Determined and estimated ship's positions are shown in Fig.2 every 30 minutes. The accuracies of estimated positions. 1. We say that the distance error is the length between the determined position and the estimated position, as shown in Fig.3, related to the drifting time every day. Furthermore standard deviations of distance errors are shown in Fig.4. 2. Differences of estimated drifting directions from determined directions are shown in Fig.5 in relation with the drifting time. And standard deviations of direction errors are shown in Fig.6. 3. Under the general condition that the drifting time is 6 to 8 hours, the distance error is 1n.m. (s.d.) and the direction error is 7°(s.d.). According to this method, we could obtain satisfactory results from various points of view for the sake of keeping watch over the fishing gear. We recommend an officer on duty to study the drifting characteristics of his own ship and apply himself to keeping watch over a fishing gear.

The feeding and condition of plaice larvae in good and bad plankton patches

In January and March, during the 1955 plaice spawning season, plankton samples were collected with a Heligoland larva net at stations on a grid around a floating radio buoy in the southern North Sea. There was a decided scarcity of suitable food for plaice larvae in the January patch, and this famine was reflected in the deteriorating physical condition of those larvae caught at the transition stage of development, when yolk reserves were becoming exhausted and an adequate external food supply essential. By March, the spring plankton outburst was in full swing. The condition of transitional larvae improved in this good food patch. Feeding started about the mid-yolk phase, mainly on plants. By the time most of the yolk had been resorbed, the appendicularians Oikopleura and Fritillaria had become the principal food items, and remained so throughout pelagic larval life.

Sono Radio Buoys

When hydrographic surveying is carried beyond visual control it is necessary to have other methods to determine the ship's position. Radio acoustic ranging supplies the method and sono radio buoys, placed at known locations, emit radio signals when actuated by subaqueous sounds. Knowing the velocity of sound in water, a system of triangulation can be extended whereby the ship's position may be determined upwards of a hundred miles from shore. Sono radio buoys consist of one or two 50-gallon steel drums supporting a radio antenna above and a stabilizing counterweight below. A sound pick-up is suspended 30 to 80 feet below the buoy, inside of which there is an audioamplifier favoring low frequencies, connected to the pick-up. When the survey ship explodes a small bomb of TNT in the water a mark is made on a chronograph tape on the ship and the sound travels to the pick-up where it is amplified and actuates transmitters in the different buoys. Radio signals returning to the ship are recorded on the same chronograph tape. Measured to 0.01 second, these time intervals enable the plotting of the ship's position.