摘要:

Abstracta set of coverage prediction diagramsis presented for the 10.2 kHz signal from each OMEGA transmitter. The diagrams show the −20 dB signal‐to‐noise ratio contours (in a 100 Hz noise bandwidth) for both local noon and local midnight. Composite diagrams are also presented on which all individual −20 dB contours are plotted for the current transmitter network for local noon and for local midnight. Similar diagrams are presented for the planned full OMEGA operational network. A full‐wave signal propagation computer program was employed to generate signal strength profiles along radial paths from each transmitter. Noise values from the CCIR noise map were applied to the profiles. Sensitivity tables showing the shifts that result from email changes in transmitted power or from seasonal variations in the noise power are also

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb01846.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractUsing data obtainedin flight, three position determining algorithms for use by general aviation aircraft were evaluated representing increasing software requirements. These were a DME only, DME/air data and blended DME/air data. Although each step represented additional software with resultant increase in position accuracy, all could be performed on a programmable electronic desk calculator. Results from the computation of aircraft position using the three algorithms are presented. The algorithms employed can be extended to accept VOR, TACAN bearing, ADF, or other NAVAID Data. To obtain the flight data an experimental system was configured and flown on a general aviation aircraft. Principal hardware elements (all with low‐cost potential) were a programmable calculator, a single DME receiver (multiplexed for multiple DME use) and a low‐cost air speed sensor (shed‐vortex principle). The flight test demonstrated satisfactory performance of these principal ele

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb01847.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.tb01848.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractRecent mission requirements in the strapdownInertial Measurement Unit (IMU) field have emphasized the need for inertial sensors which combine the capability of providing precision attitude reference with long mission life. The single‐axis hydrodynamic‐spin‐bearing gyroscope operated with pulse‐rebalance servo electronics is a prime candidate sensor for these missions. This paper provides a summary of recent test results and analytical evaluation for a high‐performance instrument of this type.The sensor parameters and performance test results summarized in this paper are based on an extensive evaluation program of the 64 PM RIG gas‐bearing gyro. The 64 PM RIG design base is the 64 AC RIG (25 IRIG), which was initially developed by MIT, with the primary difference between the two instruments being the use of a permanent magnet DC torquer (rather than an AC torquer) in the 64 PM RIG. The 64 AC RIG was originally developed and produced in large quantities for an inertially‐stabilized platform used in a missile application and has since been used as an inertial sensor on several spacecraft programs (OSO‐7 and ATS‐6). A single‐degree‐of‐freedom gyro, the 64 PM RIG utilizes a hydrodynamic gas bearing, a microsyn pickoff, a magnetic suspension, and a permanent‐magnet torquer, and is fully floated to minimize error torques about its sensitive axes. Sensor drift data is summarized which demonstrates the bias variability over a 15 hour period to be less than 0.001 deg/hr.The specific strapdown IMU performance areas which are addressed include sensor scale factor linearity and stability, the noise output of the sensor as characterized by its power spectral density, the attitude reference error buildup as a function of the interval between bias updates, and performance of the sensor in the dynamic environment typically encountered during vehicle maneuvers.The pulse‐rebalance technique implemented is binary (forced‐limit‐cycle), and uses quantized pulse‐width modulation of the gyro torquing signal. A dual‐scale design of the pulse‐rebalanced sensor has been implemented and evaluated. The pulse‐rebalanced sensor has a demonstrated capability of maintaining an attitude reference within 1.0 arc‐second for time periods exceeding 30 minutes. Test data demonstrating scale factor non‐linearity of less than 40 PPM and scale factor stability below a PPM/day is presented.The 64 PM RIG sensor is being incorporated into two strapdown IMUs which will provide the primary attitude reference for the International Ultraviolet Explorer (IUE) and the High Energy Astronomy Observatory (HEAO) spacecrafts. The six‐sensor IUE/IMU and the modular two‐sensor HEAO/IMU are discussed from the packaging (size, weight, power) and functional viewpoints. Included is a brief description of the hybridized pulse‐reba

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb01849.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractTheTimeReferenceScanningBeam(TRSB) landing system is an air‐derived data system which operates at microwave frequencies to provide guidance information proportional to an aircraft's lateral and vertical displacement from a selected flight profile. Angular position of an aircraft is measured in the aircraft by receiving ground generated fan beams which scan “to” and “fro” across the coverage sector in both azimuth and elevation. The airborne subsystem measures the elapsed time between a given “to”‐“fro” scan. The time difference is controlled to be an indication of the aircraft's angular position. This indicated angle could be corrupted by multipath. Basic to the TRSB concept is the azimuth and elevation controlled antenna radiation patterns (both in the scan and non‐scan dimensions) which, in conjunction with their high scan rates, control the multipath to an operationally acceptable level. Since the multipath is controlled primarily on the ground, there is no special impact on the cost of the airborne equipment because simple, conventional RF and signal processing techniques need only be implemented into the airbo

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb01850.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractTheU.S. Navy, through a contract with MYSTECH ASSOCIATES, INC., has developed an advanced proto‐type navigational system called MATCH‐NAV, which utilizes a mini‐computer to provide automated own‐ship geographic position in inshore, coastal navigation situations. Conceptual development of MATCH‐NAV has demonstrated the capability to provide ownship position display on digitized nautical charts, with overlay of the chart data on a radar Plan Position Indicator (PPI). Future plans include utilization of the MATCH‐NAV concept in design of a completely automated Ownship Position Display having stored nautical chart capability, which can accept navigational data inputs from such ship's sensors as Loran‐C, Omega, radar and other precision electronic navigation systems, including satelite systems. The goal—to provide continuous, accurate, real‐time visual display of ship's position in restricted coastal waters.This paper discusses the MATCH‐NAV concept and its potential applications in future

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb01851.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.tb01852.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

AbstractTheNAVSTAR GlobalPositioningSystem(GPS) is the satellite navigation system of the future. It is now in the development stage of its validation phase. Precise estimation and prediction of navigation satellite ephemerides and frequency standard characteristics are essential to projected user navigation accuracy. This paper presents the approach being implemented to achieve that accuracy.The approach blends the successful batch estimation technique (CELEST) developed by the Naval Surface Weapons Center with an on‐line Kalman estimation technique to be implemented at the GPS Master Control Station (MCS). Both techniques use the same precisely measured and smoothed pseudoranging data collected by geometrically spaced Monitor Stations (MS) located at Hawaii; Elmendorf AFB, Alaska; Guam; and Vandenberg AFB, California.CELEST employs detailed force models in a batch‐weighted least‐squares estimation of the ephemerides. It then predicts the ephemerides and partial derivatives for yet another long period. These ephemerides and partial derivatives provide excellent predicted references and simple ephemeris models for the linear recursive Kalman estimator to be resident at the Master Control Station.The Kalman estimator operates about the predicted reference to “fine tune” the ephemerides and estimate frequency standard characteristics in a timely on‐line manner. Timeliness is necessary to update the frequency standard drift characteristics. The ephemeris and frequency standard models are also used to predict ephemerides and characteristics on a daily basis using last‐minute estimates. Precise representation of the predictions are then transmitted to the satellites which, in turn, transmit current dat

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb01853.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

Marine Navigation Textbook;MARINE NAVIGATION 1, PILOTING, by Richard R. HobbsMARINE NAVIGATION 2, CELESTIAL and ELECTRONIC, by Richard R. HobbsCelestial Navigation RefresherPARTICULARIZED NAVIGATION, by Frances W. WrightRadar Plotting Techniques;REAL TIME METHOD OF RADAR PLOTTING, by Max H. Carpenter and Wayne M. Waldo

ISSN:0028-1522    

DOI:10.1002/j.2161-4296.1976.tb01854.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.tb01855.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY