Tracking Equipment Research Articles

A self-steering planar array antenna for satellite broadcast reception

The active planar array antenna offers a number of advantages, including use as a portable antenna for easy reception of direct Ku-band satellite television broadcasts. This paper presents a newly developed active planar array antenna which provides electronic beam-tracking without mechanical tracking equipment. The features of the antenna are: (1) use of a series-parallel fed microstrip array, (2) electromagnetically excited array by a coplanar patch connected to the coplanar waveguide, and (3) low noise down-converters and self-phasing units incorporated into the feed circuits for electronic beam-tracking. The paper discusses the design of the coplanar waveguide fed coplanar patch and the configuration of a self-phasing active planar array antenna. The measured gain of the experimental 9-element unit array antenna without active devices is 13.4 dBi at 11.85 GHz. Experimental results for a 216-element self-steering planar array of size 147/spl times/220.5 mm are also presented.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Locus of interpretive and inference processes during text comprehension: A comparison of gaze durations and word reading times.

This study investigated the locus of interpretive and inference processes during text comprehension. Two positions were contrasted: the buffer-integrate-purge position, which assumes that text-level interpretive and inference processes operate at sentence or clause boundaries, and the immediacy position, which assumes that interpretive and inference processes operate as soon as possible. We contrasted 2 methods of collecting word reading times: gaze durations and self-paced word reading times. In simple narrative passages, there was an increase in word reading times for end-of-clause words when self-paced reading times were collected, but there was a decrease when gaze durations were measured with eye tracking equipment

Proving Safety of a Railway Signalling System Incorporating Geographic Data

Solid State Interlocking (SSI), a computer-based railway signalling system, is used extensively by British Rail and also by other railway administrations. An interlocking is implemented as a generic program, the same for all areas, together with a geographic database which serves as a detailed map of the track and signalling equipment in a specific area of control. We formally model SSI behaviour as that of a finite state automaton with next-state and output functions defined by geographic data. Safety of interlocking is modelled as a family of predicates of state, and a proof strategy based on mathematical induction is designed for showing that safety predicates remain invariant over an indefinite number of cycles. The strategy allows for a mixed approach to proof: high-level hand proof of lemmas relating to the transitivity of safety, and lower-level mechanized proof of detailed steps. The formal model also lends itself to investigation of the safety of behaviour patterns in the environment controlled by an interlocking. A pattern of is a subset of input sequences, and the automaton connects this to a set of states which remain invariant under such input. This connection is shown to induce topologies into state-space and into the environment.

Tracking Coastal Sharks with small boats: Hammerhead Shark Pups as a case study

Acoustic telemetry techniques have been adapted for use with small boats to facilitate tracking of nearshore reef species. In addition to permitting tracking in areas where manoeuvrability and quick responses are required, the system has modest operating costs that make tracking experiments a viable option for a wide range of researchers. Tracking and communication equipment can be powered for several days by a single 12-V 8D truck battery. Current topics in shark biology that are amenable to these tracking techniques are discussed. For instance, hammerhead pups have been tracked on their natal grounds for periods of up to 13 days. Their daytime movements appeared to be restricted to a well defined 'core area' where a school of sharks hovered between 1 and 3 m off the lagoon floor. At night, the sharks became more active, expanding their range of movements before returning to the core area the next morning.

Supplemental‐information‐seeking behavior of cardiovascular nurses

The Krikelas model was used as a framework for investigating supplemental-information-seeking behavior of cardiovascular nurses. (Supplemental information is that which is not available from memory and could be made available by computer). One hundred seventy-five instances of supplemental-information-seeking behavior were collected from 46 cardiovascular nurses in three metropolitan hospitals. Self-report and observation-interview methods were used. Findings indicated that the nurses sought patient-specific data most frequently, followed by institution-specific data and domain knowledge. They needed a surprisingly large portion of the information to track people, equipment, medications, and reports. The findings have implications for nursing information system design.

Underwater Telemetry as a Tool in Aquaculture Research and Development

Small acoustical transmitters may be used to obtain data from tree swimming fish. The main principles behind this technique are described together with some of the equipment developed for such purposes. Some examples are briefly discussed where heart beats, depth and temperature are measured to describe fish behavior. Automatic fish tracking equipment that have been used to track fish within an enclosed area is also described.

Underwater Telemetry as a Tool in Aquaculture Research and Development

Abstract Small acoustical transmitters may be used to obtain data from tree swimming fish. The main principles behind this technique are described together with some of the equipment developed for such purposes. Some examples are briefly discussed where heart beats, depth and temperature are measured to describe fish behavior. Automatic fish tracking equipment that have been used to track fish within an enclosed area is also described.

Economics of satellite communications systems

This paper is partly a tutorial, telling systematically how one goes about calculating the total annual costs of a satellite communications system, and partly the expression of some original ideas on the choice of parameters so as to minimize these costs. The calculation of costs can be divided into two broad categories. The first is technical and is concerned with estimating what particular equipment will cost and what will be the annual expense to maintain and operate it. One starts in the estimation of any new system by listing the principal items of equipment, such as satellites, earth stations of various sizes and functions, telemetry and tracking equipment and terrestrial interfaces, and then estimating how much each item will cost. Methods are presented for generating such estimates, based on a knowledge of the gross parameters, such as antenna size, coverage area, transmitter power and information rate. These parameters determine the system performance and it is usually possible, knowing them, to estimate the costs of the equipment rather well. Some formulae based on regression analyses are presented. Methods are then given for estimating closely related expenses, such as maintenance and operation, and then an approximate method is developed for estimating terrestrial interconnection costs. It is pointed out that in specific cases when tariff and geographical information are available, it is usually better to work with specific data, but nonetheless it is often desirable, especially in global system estimating, to approximate these interconnect costs without recourse to individual tariffs. The procedure results in a set of costs for the purchase of equipment and its maintenance, and a schedule of payments. Some payments will be incurred during the manufacture of the satellite and before any systems operation, but many will not be incurred until the system is no longer in use, e.g. incentives. In any case, with the methods presented in the first section, one arrives at a schedule of costs and payments for all the items and the years in which they will be incurred. The second category of costing problems is one of financing or engineering economics. All the costs are first “present valued” to some reference period using rates of return appropriate to the particular situation. One finally arrives at sets of annual costs which can be used as the basis for setting lease costs or revenue requirements and tariffs. The correspondence between methods using discounted rates of return and capital recovery formulae on one hand and those using various depreciation schedules, such as is typical of regulated industries on the other hand, is discussed. The remainder of the paper is devoted to discussing the relationship between critical parameters, such as replacement schedules, design lifetime, satellite power and Earth station antenna size, and the overall costs. It is shown that optima for these parameters may exist and can be calculated. In particular, the optimization of satellite replacement schedules to minimize the present value of total investment over a very long period is presented, along with simplified versions of the theory suitable for system planning. The choice of EIRP is also discussed and a procedure for choosing the value that minimizes the costs is shown.

Stability of rotary mining excavators used in the extraction of refractory raw materials from deep strata

It has been established that a large group of clay deposits is characterized by variations in the foundation strata and therefore it frequently happens that the rotary mining excavators must be operated on slopes up to 8°. The movement and operation of the rotary excavators on a sloping surface makes it necessary to draw up more stringent requirements for the stability of the machines. In addition to the fulfilment of the conditions to prevent the machine overturning, the conditions relating to the prevention of the machine slipping on an inclined surface must also be observed. The fulfilment of the latter depends significantly on the coefficient of attachment of the supporting surfaces of the tracking equipment to the ground. The installation of cleats ensures that rotary excavators can be operated on slopes up to 8°.

静止衛星の軌道決定精度に関する考察

The Orbit determination accuracy required to maintain a geostationary satellite within ±0.1° longitude and latitude band is discussed.And through an experiment of the orbit determination of INTELSAT-IV and ATS-I, it is confirmed that this accuracy can be accomplished by the present tracking equipment and orbit determination software.Moreover, some useful suggestions are givento develope a more simplified station keeping software system for a geostationary satellite.

Concepts For Future Vessel Traffic Systems

a unique aspect of the San Francisco Experimental Vessel Traffic System has been its extensive use of real time automatic processing technology. Automatic detection and tracking of vessels in radar coverage areas has successfully been accomplished even in the presence of clutter. Vessel movement information has been extracted, presented to operators on computer-animated displays, and traffic analyzed both automatically and at the request of operators. But these demonstrated capabilities should be employed only as a guide to the design of future systems and not interpreted as a literal prototype configuration. Future system designs should assume traffic will be controlled, rather than advised. Risk analysis based upon port geometry, traffic levels, and minimum turning radius can contribute to assessing deployment priorities. Vessel routing should be constrained to follow narrow tracks rather than broad lanes. A minimum configuration would be based upon a computerized Vessel Movement Reporting (VMR) system. Data entry and retrieval terminals could be available within the maritime community. Information, including guidance, could be selectively distributed to active ships via a novel multiplexed television transmission. All radar configurations would include automatic detection and tracking equipment. Finally, area navigation systems could be integrated with VTS. The opinions expressed in this document are those of the author, presented in the interest of stimulating discussion, and they do not necessarily reflect the views of either the Applied Physics Laboratory or the United States Coast Guard.

日本陸上競技における施設・用器具発達に関する史的考察

日本陸上競技における施設・用器具発達に関する史的考察

Satellite Radio Navigation

In this review paper the basic requirements and configuration of a typical Satellite Navigation System are outlined. Various techniques such as measurement of angle, range and range rate for position fixing applications are discussed in detail. The orbits employed and the frequency ranges appropriate to each technique are considered. The relative advantage and disadvantages of these techniques are also dealt with. The performance of these systems for Military application are highlighted. It is concluded that the disadvantages such as requirement of orbital tracking and complex air-borne equipment will be outweighed by the potential advantages, the system possess such as all weather position fixing and wide coverage.

A COMPARISON OF THE WIND SPECTRA CALCULATED FROM DATA OBTAINED BY INDEPENDENT SAMPLING METHODS1

Abstract The power spectrum of the wind is estimated from independent wind measurements taken at an altitude of 1,500 ft above the ground in the frequency band from 0.0625 to 1.5 cycles hr–1. Wind data were obtained simultaneously from radar tracking equipment and from wind sensors on a nearby tower. These data were collected at 20-min intervals over a 5-day period. Analyses of the wind spectra and coherence indicated a good correspondence in the two time series, considering that the data were obtained at slightly different locations and by completely independent measurements. It is concluded that radar wind-finding measurements can provide valid estimates of the wind spectrum in the frequency band analyzed.

Simulation analysis of transmission-based signalling systems for metro applications

Transmission-Based Signalling (TBS) Systems offer Metro administrations major operational benefits in terms of improved line capacities, improved traffic regulation and possible reductions in journey time. Other benefits include large reductions in track equipment and associated cabling, improved maintenance facilities and the capability to overlay onto existing Fixed Block installations. Whilst the steady-state headway-performance of Moving Block based TBS systems is well understood, the dynamics of train performance when signalling interaction occurs has received little attention. Here analytical studies are difficult because of the nonlineanties associated with both the safety algorithms and the control system The paper describes simulation models that identify the basic control problems and their potential effect on train performance.

A discussion on orbital analysis - Radio tracking at Winkfield

Winkfield is one of the stations in the Space Tracking and Data Acquisition Network (Stadan) of the U.S. National Aeronautics and Space Administration (N.A.S.A.) and is operated by the Radio and Space Research Station as a joint venture with N.A.S.A. The stations in the network, using standardized equipment supplied by N.A.S.A., receive by radio telemetry measurements from the various experiments in the satellites, they command the functioning of satellites and they track them. Tracking, with which this paper is concerned, means the measurement of quantities which contribute to the determination of the positions of satellites as a function of time. About ten stations in the network use tracking equipment and methods identical with those used at Winkfield. The network operates 24 h a day, its functioning being coordinated by the Goddard Space Flight Center of N.A.S.A. by means of teleprinter circuits which also serve to convey the raw tracking information from the stations to the N.A.S.A. computer facilities.

Photographic Techniques for Project Mercury Ground Range Evaluation

The NASA Project Mercury spacecraft is tracked through its launch, orbit, and recovery phases by a world-wide network of tracking stations. The short duration of the manned flights and the paramount considerations of the astronaut's safety require a much more sophisticated ground range than is needed for unmanned flights of longer duration. Thorough testing of the ground acquisition and radar tracking equipment, prior to the spacecraft flights, was accomplished economically with boresight camera techniques, using DC-3 and C-54 aircraft specially equipped to simulate an orbiting spacecraft. Development of this test program is described, along with a discussion of the photographic equipment employed, the problems and limitations encountered and the aircraft equipment.

Inertial systems in space vehicles

This paper discusses the use of inertial elements in space vehicles for attitude control and navigation. Some limitations of inertial systems in this environment are described and it is shown that inertia alone is not adequate for most space applications. However, the use of inertia to bridge the gaps between information from other sources can simplify the requirements for other sensors in the satellite, and also on the ground tracking equipment. This is illustrated by some examples and by discussion of space vehicle.

Exploration in Llanos of Colombia: ABSTRACT

The Llanos of Colombia, comprising the eastern portion of the country, is an alluvium-covered, featureless, grassy plain that covers an area of about 75,000 square miles. Except for a short dry season from December to March heavy rains occur almost every day. Access to the area is difficult and for the major portion of the year special track equipment or helicopters must be used for exploration operations. Structurally the Llanos form an asymmetrical basin similar to that of eastern Venezuela or western Canada. There is a shelf area to the east with sediments dipping uniformly off the Guiana shield and increasing in thickness to the west to form a major trough in front of the thrust faulted Eastern Cordillera. The entire geological sedimentary column outcrops along the we tern border of the Llanos with excellent reservoirs, source rocks, and attendant oil seeps. Approximately 26,500,000 acres are held in the basin by six major oil companies at this time. To date the geology of the bordering Eastern Cordillera has been mapped in considerable detail, reconnaissance seismograph, gravity, and local magnetometer surveys have been run over the more attractive portions of the basin, and 22 wells have been drilled. Although some encouraging oil shows have been encountered in wells in the southern margin of the basin, no commercial oil has been discovered to date. End_of_Article - Last_Page 1254------------

British High Altitude Rocket Research Program

A high altitude rocket is being developed in the U. K. by the Ministry of Supply for a joint research program between the Royal Aircraft Establishment and a number of universities. The vehicle is 25 ft long, I7V2 in* in diam and employs a solid propellant motor. When launched near the vertical, it is expected that an altitude of 490,000 ft will be achieved with a payload of 65 lb. Later nights with a boost addition are hoped to reach 700,000-ft altitude. The missile is stabilized by three fins but it is not guided during flight and will carry telemetry, doppler, and beacon tracking equipment in addition to the payload. The first trainable launcher has already been installed at the Australian rocket range at Woomera and firings will begin there early in 1957.