摘要:

ABSTRACTIn the past, U.S. Polaris (A‐3) and Poseidon (C‐3) SSBNs (ballistic missile equipped, nuclear powered submarines) took relatively frequent navigation fixes at specified but clsssified periodic rates to compensate for the degradations of gyro drift‐rate. However, a randomization of the fix taking was called for to preclude enemy deciphering of the frequency of fix‐taking as the enemy attempts to enhance its surveillance of U.S. SSBNs. Since warm‐standby navigation configurations (such as two complete Ships Inertial Navigation Systems, SINS) are usually utilized onboard U.S. SSBNs anyway to reap the benefit of high reliability/availability through online modular repair, the so‐called Difference Monitoring procedure consisting of a comparison of the outputs of both these available INSs was instituted in 1976 to randomize the fix taking for C‐3 SSBNs.One contribution of this paper is to use existing results of Helstrom from level‐crossing theory for the output of nonlinear operations (e.g., the RSSing of latitude and longitude error to obtain radial position error) to provide an analytically tractable theoretical model for the previous empirical procedure of Difference Monitoring. Using the parameters of RMS level and correlation‐time of the underlying INS, this analytic model can be exploited to set the constant decision threshold to achieve aspecified averageinterval between position fixes. A second contribution of this paper is to present an expression for the related variance. A comparison between actual SSBN patrol statistics and analytically predicted results for alternative threshold settings is included; however, time and navigation accuracy scales are concealed to prevent divulgence of national security information.Measures of SSBN detectability to enemy surveillance should apparently also be updated in a manner herein suggested to no longer assume SSBN fix taking at a periodic rate. Adoption of this suggestion enables use of an absolute evaluation technique (based on Pareto‐optimality) already developed and utilized as described herein as a third contribution for gauging the “goodness” of either randomized or deterministic SSBN fix strategies over and specified time epoch. Two Electrostaticially Supported Gyro Navigators (ESGNs) have been postulated as a candidate configuration for D‐5 Trident II SSBNs, where Difference Monitoring will again be as appropriate

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00776.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThis paper presents the design philosophy, construction, programming, testing and test results of a simplified NAVSTAR GPS Receiver for marine application. The efforts described resulted in a single frequency, C/A code only, sequential receiver which is expected to be competitive in cost to a transit satellite receiver of similar construction.

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00777.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThe LORAN‐C system is one of the candidate radionavigation systems currently under evaluation by the FAA with regard to its suitability as the primary or supplemental domestic navigation system for civil aviation during the post 1995 time period. Reliability of a candidate system to provide continuous navigation signals for airborne applications has been adopted as one of the evaluation criteria. The key consideration in the system reliability assessment is the impact of station outages and the resultant loss of navigation signals to the aviation users.This paper presents an analytical technique for evaluating the reliability of the LORAN‐C system over the conterminous United States (CONUS). Emphasis is placed on the technique itself and not the specific reliability statistics. The technique is applicable to the analysis of the existing USCG ground station configuration, as well as any proposed full‐CONUS coverage station configuration.The technique is based on the use of a Markov Chain model to provide a probabilistic measure of system unreliability and incorporates signal strength, relative geometry, and receiver configuration which define system coverage. A simplified analytic procedure is employed to bound the system unreliability and a numerical example is presented based on preliminary LORAN‐C station reliability statistics for solid‐state ground stations and a simple recei

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00778.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThis paper describes an accuracy performance analysis of a ring laser (RL) strapdown marine gyrocompass. Theoretically derived relationships and covariance analysis results are presented to indicate the effect of ring laser errors on heading accuracy and on settling time. Test results obtained with a pre‐production model of the RL strapdown gyrocompass are also shown, and they illustrate the capability of this system to meet U.S. Navy Type I at‐sea performance requireme

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00779.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTThis paper reports on a flight evaluation of LORAN‐C which was part of a long range study of area navigation systems for general aviation. Tests involved two different LORAN‐C receivers, 6 different aircraft and a variety of antennas. Uncorrected position fixes were typically accurate to one quarter mile. With measured corrections repeatability was good to within 200 ft. (2σ). Signal reliability was 99.7%. The receiver was not sensitive to atmospheric noise. The time difference grid demonstrated a long term stability of 0.3 microsecond. Vertical whip and ADF E‐field antennas were found suitable for airborne use. LORAN‐C was found satisfactory for instrument approaches to runways at general aviation airports where published latitude‐longitude coordinates were available. Accuracy was further improved by using locally measured LORAN‐C time difference

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00780.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

ABSTRACTTexas Instruments has developed a multiplexing GPS receiver that has many of the advantages of a continuous receiver at the low cost of a sequencing receiver. The multiplexing concept is explained. The receiver architecture is described. Advantages of multiplexing over the conventional receiver are highlighted. Applications of the multiplexing receiver to meet requirements now being met with single‐channel, two‐channel, and five‐channel sets are discussed. Data comparing the performance of this multiplexing to conventional approaches are presented. A multiplexing GPS receiver solves difficult problems. Several of these applications are presented, including angle determination, single‐channel differential GPS, area navigation and precision approach, and geodetic surveying. All applications examined have yielded a unique advantage with the multiplexed GPS receiver over a conventional GPS r

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00781.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

Book reviewed in this article:Navigational AstronomyASTRONOMIA NAUTICA, Admiral Mario BiniCOMPACT DATA for NAVIGATION and ASTRONOMY for 1981 to 1985 Royal Greenwich Observatory Bulletin No. 185 by B. D. YallopEXERCISES IN ASTRO‐NAVIGATION by Gordon WatkinsCollateral InterestPILOTING, SEAMANSHIP AND SMALL BOAT HANDLING, 55th ed. Charles F. Chapman, edited by Elbert S. Molon

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00782.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00783.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1981.tb00784.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY