ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00728.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTNeae real‐timeATS‐5 satellite positions and short term position predictions were derived from an experimental L‐band trilateration network developed by the General Electric Company under contract to NASA. Satellite position accuracies of approximately 0.0002 degrees in latitude and longitude and 20 meters in earth center distance were demonstrated. Individual slant range measurements from the master ground station to the satellite were precise to within 12 meters; from the satellite to each of two automatic remote transponders, 23 meters.The trilateration network comprised a master ground station near Schenectady, New York and remote unmanned transponders in Buenos Aires, Argentina and near Wahiawa, Hawaii. Tone‐code ranging signals consisting of a short 9.8 kHz tone burst followed by the unique digital identification code of the addressed transponder frequency modulated a 1651 MHz carrier within a total RF bandwidth of 60 kHz. After a precisely defined internal time delay, only the transponder that recognized its own unique address code retransmitted a tone‐code‐data response. Self calibration circuits in the transponders returned a measurement of the transponder internal time delay after every interrogation, eliminating time delay variations as a major source of slant range measur

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00729.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTThe unified signal processor(USP) performs the functions of dedicated analog and digital hardware using a timeshared microprocessor which is controlled by a program stored in a read only memory (ROM). The basic advantages are high reliability, low cost and parts count, high flexibility, freedom from drift and adjustments, unlimited precision in signal processing and the USP lends itself ideally to micro‐electronic implementation.It has been incorporated in the AN/ARN‐119 TACAN navigation set, resulting in improved performance and a two‐fold improvement in parts count and reliability as compared to conventional TACAN signal processors. The integrated system has successfully completed flight, qualification and reliability tests. All functions have been verified and the performance equals or exceeds that of conventional microelectronic TACAN sets.The USP extracts and displays range and bearing, performs automatic gain control and self test, and switches antennas. It operates off the TACAN video signal and simultaneously, generates serial digital output signals and analog output signals compatible with synchro indicators.Algorithms for range and bearing acquisition, discrete phase‐locked loops, digital filters, automatic gain control, synchro to digital conversion, and data formatting were developed and verified through computer simulations. The microprocessor was designed around the INTEL 8008–1 central processing unit chip. The control program consists of 6000 8‐bit instructions, which are stored in 3 read only memories. A common 8‐bit tri‐state data bus is used to communicate between the central processing unit, the memory and the interfaces.Interfaces necessary to convert between analog signals and digital signals compatible with the data bus form an integral part of the signal processing functions. Portions of these circuits are based on similar circuits used in conventional TACAN sets. Other circuits such as the digital‐to‐synchro converter, the synchro‐to‐digital converter, the range and bearing counters, the ID‐tone detector, the pulse pair detector, the north burst detector, the encoder and the data rat

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00730.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTThe state‐of‐the‐artin collision avoidance technology for ships consists of systems employing digital signal processors to compute ship tracks, target closest point of approach (CPA), and time‐to‐CPA. This information is presented to the ship's officers through CRT displays. Some systems provide a means for selecting and displaying trial‐and‐error maneuvers. Like the available shipboard radar systems, existing collision avoidance equipment relies heavily upon the ability of the ship's officer to process information and make decisions under conditions of severe stress.This paper will discuss the potential use of a shipboard digital computer to compute additional information from the radar video data and generate maneuver cues as an aid in collision avoidance. Techniques for generating collision avoidance maneuvers will be related to ship maneuvering capability, as determined by its speed and turning characteristics. One example will be given to illustrate the relationship between CPA and miss distance for cooperative and uncooperative maneuvers, and another will show how dynamic maneuver charts can be used by a privileged vessel to decide when to take action to avoid a bu

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00731.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTBecause of the availabilityof high level solid state switches, it is now practical to implement efficient pulse transmitters in the 100 kHz frequency region by discharging, in sequence, a multitude of high level half cycle generators into a properly designed RF output circuit; this circuit must include the actual radiating antenna.This paper presents design equations which are directly applicable to the RF circuit design of such a transmitter, and shows that the simplest practical overall output circuit turns out to be a straightforward double tuned bandpass filter.Because, in the 100 kHz carrier region being considered, the natural antenna bandwidth is often very much narrower than that required to “pass” the desired pulse rise time, the paper considers in detail both the phenomenon involved and the circuit design involved which will enable an antenna current having any specified pulse rise time to be produced no matter how narrow the natural antenna bandwidth may be. It is important to realize that this capability is accomplished without the addition of power consuming loading resistors.After the half cycle generators—overall network combination has been designed to produce the desired pulse leading edge, one is faced with the problem of correctly discharging the network so that it produces a specified pulse decay shape. This problem is also considered in this paper and design equations are presented for the switched‐in network which must be used to produce a specified pulse deca

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00732.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTIn celestial navigation, the advent of the hand held or mini‐computer brought forth a plethora of methods for the solution of spherical triangles. The azimuths and altitudes thus derived have not only eliminated the need for bulky tables but also have speeded up the determination of the data needed for the graphic construction of intersecting lines of position from which the “fix” is derived. In this conventional type of solution, the corrected sextant altitude is compared with the computed altitude then, from the assumed position, the line of position is constructed perpendicular to the azimuth of the body observed and either towards the body or away from it depending upon whether the observed altitude is greater or less, respectively, than that which has been computed.Extremely sophisticated systems are being developed which combine special computer systems directly with the sextant. However, the present paper relates only to the minicomputers currently on the market and their apparent ultimate utility in the celestial navigation field—the direct display of both latitude and longitude without recourse to graphic

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00733.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTThis paper is divided into two parts. Part I attempts to provide, in a general way, the operating atmosphere that exists on many a ship's bridge when maneuvering in traffic with some of the inherent problems and stresses that continue to prevail, even with the best equipment and training.Part II presents a proposed solution to these problems. Hopefully it will provide masters and watch officers with increased assurance that coordinated maneuvering with other vessels is possible. Using the Collision Avoidance Grid (CAG) System, in conjunction with radar and VHF radiotelephony, collision avoidance and positive control over the situation could be a rapidly achieved goal withlittle or no further training and no additional hardware.

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00734.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTthis paper describesa sequential algorithm which employs sequential passive time difference measurements anda‐prioriestimates of position and bias parameters to determine the navigator's position, clock and frequency bias parameters. A covariance analysis is presented using simulated measurements from the NTS‐1 satell

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00735.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

ABSTRACTResearchers, scientists, and engineersare improving the state‐of‐the‐art in magnetic suspension technology.The soft coupling characteristic of magnetic suspension systems have made possible rotational systems with very low self‐induced noise or vibration. The rotational systems have been found to be accurate to within fifteen seconds of arc when the axis of rotation is compared to the vertical. Recent NASA funded projects have resulted in modification of the wheel itself. In that application, only the rim remains while the hub and spokes have been eliminated.These improvements have implication for navigation because they can have an influence on the heart of navigational instrumentation in space age appli

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00736.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb00737.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY