Showing papers on "Geodetic datum published in 1973"
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TL;DR: One-at-a-time experiments are always done when the experimental system is set up to produce single results or pairs of results as discussed by the authors, but may give biased estimates when random error is small compared to main effects expected.
Abstract: One-at-a-time experiments are always done when the experimental system is set up to produce single results or pairs of results. When random error is small compared to main effects expected, such experiments are economical, but may give biased estimates. These biases can usually be described by two-factor interactions (2fi). Minimal augmentations of standard one-at-a-time sequences are given, first to separate main effects from 2fi, then to estimate each 2fi separately. Each new datum produces one or more new estimates.
202 citations
01 May 1973
TL;DR: The results of a determination of the coordinates of about 70 tracking stations are presented in this paper, where the data were deived with the aid of dynamical techniques from precise reduced optical and laser observations of geodetic satellites.
Abstract: The results of a determination of the coordinates of about 70 tracking stations are presented The data were deived with the aid of dynamical techniques from precise reduced optical and laser observations of geodetic satellites It is attempted to establish a reasonable accuracy estimate through a comparison of the data with other independent solutions A brief description is given of the independent solutions used as a source of comparison
21 citations
TL;DR: In this article, it is shown that the so-called "free adjustment" has meaning only when applied to estimable parametric functions and that unbiased estimates are desirable in geodesy.
Abstract: Recently, a number of articles in the geodetic literature have appeared which exploit the concept of generalized inverses in geodetic adjustments. It is shown here, under the assumption that unbiased estimates are desirable in geodesy, that the so-called “free adjustment” has meaning only when applied to estimable parametric functions.
20 citations
TL;DR: In this paper, the theory required to obtain the error ellipses of network stations without using the actual values of the observations forming the network is given, and the importance of this concept in the optimisation of geodetic networks is pointed out by means of an example.
Abstract: The theory required to obtain the error ellipses of network stations without using the actual values of the observations forming the network is given. The importance of this concept in the optimisation of geodetic networks is pointed out by means of an example.
17 citations
01 Jan 1973
TL;DR: In this article, a solution for the geodetic boundary value problem which defines height anomalies to + or - 5 cm, if the earth were rigid, has been obtained, taking into account the existence of the earth's topography, together with its ellipsoidal shape and atmosphere.
Abstract: A solution is obtained for the geodetic boundary value problem which defines height anomalies to + or - 5 cm, if the earth were rigid. The solution takes into account the existence of the earth's topography, together with its ellipsoidal shape and atmosphere. A relation is also established between the commonly used solution of Stokes and a development correct to order e cubed. The data requirements call for a complete definition of gravity anomalies at the surface of the earth and a knowledge of elevation characteristics at all points exterior to the geoid. In addition, spherical harmonic representations must be based on geocentric rather than geodetic latitudes.
14 citations
01 Oct 1973
TL;DR: In this paper, a 6m datum was constructed from an inner datum rod made from 10 mm bore galvanized tube and a guard tube of 25 mm bore, together with specially manufactured end pieces.
Abstract: Equipment and techniques are described in sufficient detail for those who may wish to make settlement observations on buildings. It is important that settlement observations be made both during construction and for a period of years thereafter. Information that must be recorded in addition to levelling records is listed. Levelling stations should be purpose-made units built into the structure. The requirements of such stations are outlined. A levelling station is described (and illustrated) which consists of a stainless steel socket (65 mm long and 22 mm diameter), which is set in a hole in the structure, and a removable levelling plug of about the same dimensions on which the base of a staff is held when levels are taken. The installation in prepared holes, casting in concrete and extension of levelling stations are detailed. The requirements for datums are discussed. A 6m datum described which is constructed from an inner datum rod made from 10 mm bore galvanized tube sorrounded by a guard tube of 25 mm bore, together with specially manufactured end pieces. Details are given of the installation. A precision level was used together with an invar staff at 10 mm intervals. The procedure is described. The method of presentation of results is illustrated by observations taken over 13 years. The datum judged to be most reliable should be called the main datum (DI) and its level designated as 0.00 mm, as necessary to avoid negative levels, 1 000.00 mm etc. The frequency of levelling will be dictated by the specific case.
9 citations
01 May 1973
TL;DR: In this article, a multi-year study and analysis of data from satellites launched specifically for geodetic purposes and from other satellites useful in Geodetic studies was conducted. The program of work included theoretical studies and analysis for the geometric determination of station positions derived from photographic observations of both passive and active satellites.
Abstract: A multi-year study and analysis of data from satellites launched specifically for geodetic purposes and from other satellites useful in geodetic studies was conducted. The program of work included theoretical studies and analysis for the geometric determination of station positions derived from photographic observations of both passive and active satellites and from range observations. The current status of data analysis, processing and results are examined.
8 citations
01 May 1973
TL;DR: The program of work included theoretical studies and analysis for the geometric determination of station positions derived from photographic observations of both passive and active satellites and from range observations.
Abstract: A multi-year study and analysis of data from satellites launched specifically for geodetic purposes and from other satellites useful in geodetic studies was conducted. The program of work included theoretical studies and analysis for the geometric determination of station positions derived from photographic observations of both passive and active satellites and from range observations. The current status of data analysis, processing and results are examined.
6 citations
TL;DR: A detailed summary of the results of the survey can be found in this article, along with a list of the locations where tilt and strain measurements are being carried out in the Earth's crust.
Abstract: A list of strainmeter locations is presented. The geographical coordinates and instrumental parameters of more than 250 instruments are summarized together with information concerning altitude, depth below ground level and rock type. The following pages are a partial summary of the response to a questionnaile circulated in 1969 by the Royal Society concerning the study of small-scale movements of the Earth's crust. The questionnaires were sent to the national committees of all countries corresponding to the International Association for Geodesy and several hundred replies were received. The purpose of the questionnaire was to ascertain the extent and sophistication of precise measurements of crustal movements. The replies ranged from geodetic triangulation and trilateration work to the development and application of instruments for the measurement of tilt, strain and gravity. Much of the work described has advanced since then and new techniques have evolved, especially in the field of long-distance geodetic work. It would not be possible to do justice to the present wide range of precise geodetic work and so it has been omitted from this summary. However, it is possibly of interest to many to learn of the large number of locations in which tilt and in particular strain are being measured. The reader interested in the distribution of observatories where tilt and gravity measurements are taking place is referred to Melchior (i969). A summary of the location of Earth strainmeters is presented. However, it should be remembered that the commendable move towards locating these instruments in non-observatory environments to study 'real geophysical problems' must inevitably mean that the list is largely incomplete.
5 citations
Patent•
09 Feb 1973
TL;DR: In this article, a ship's inertial navigation system (SINS) is used to measure the angular difference between the local or astronomic vertical at a point and the normal to the reference ellipsoid of the earth at that point.
Abstract: A method for obtaining at a point the value of earth''s vertical deflection, which is the angular difference between the local or astronomic vertical at a point and the normal to the reference ellipsoid of the earth at that point. The position coordinates of the point is measured by using a ship''s inertial navigation system (SINS) which is compared with corresponding the position coordinates of the same point measured by using a geodetic reference apparatus, such as a long-range electronic navigation system (LORAN) or high precision short-range navigation (HIRAN). The difference between the two values of the position coordinates of the point; also called dPT total position error; is due to vertical deflection; i.e., the difference between local vertical and geodetic vertical or normal to the reference ellipsoid of the earth at that point; error due to gyro drift of the SINS; and reference velocity error. Contributions due to error because of gyro drift and to error in reference velocity are subtracted from dPT, the value of the difference between the two values of position coordinates of the point, using SINS RESET technique and a standard reference velocity technique respectively so as to obtain dPV, position error due to earth''s vertical deflection. The value of dPV is then mainly due to earth''s vertical deflection at that point, from which the value of vertical deflection at that point is obtained using SINS INVERSE FILTER technique.
5 citations
01 Jan 1973
TL;DR: The application of observations from the ANNA satellite to solve geodetic problems is discussed in this paper, where a method for using correlated satellite observations for the accurate recovery of ground station positions and applying the result to the adjustment of the National Geodetic Survey worldwide network is developed.
Abstract: The application of observations from the ANNA satellite to solve geodetic problems is discussed. The establishment of a worldwide network of optical observing stations by the National Geodetic Survey is reported. The geodetic network is composed of 49 observing stations, more or less evenly distributed throughout the world. A method for using correlated satellite observations for the accurate recovery of ground station positions and applying the result to the adjustment of the National Geodetic Survey worldwide network was developed.
Patent•
12 Dec 1973
TL;DR: In this article, the authors proposed a navigational instrument which can be used as an elementary navigation teaching aid, which can also be used for finding Local Time by apparent sun or by mean sun, finding Greenwich Mean Time (or any other standard zone time) if the longitude is known, finding longitude if Greenwich Mean time is known; finding latitude, finding the sun's altitude, zenith distance, amplitude and declination; finding the date, finding observer's geographical position by fix; and finding observer position by land marks.
Abstract: The invention relates to a navigational instrument which can be used as an elementary navigation teaching aid. It can also be used for finding Local Time by apparent sun or by mean sun; finding Greenwich Mean Time (or any other standard zone time) if the longitude is known; finding longitude if Greenwich Mean Time is known; finding latitude; finding the sun's altitude, zenith distance, amplitude and declination; finding the date, finding observer's geographical position by fix; and finding observer's position by land marks. The instrument comprises a base member having a datum such as a meridian line and being capable of being set in a predetermined position, means of measuring the angle between a line of sight from an object and the datum, means of finding local time by the apparent sun which means is rotatably mounted on a pivot on the base member, and a source of reference from which the ephemeris of the sun proper to any day of any year can be obtained. The instrument has the advantage of being robust and simple.
01 Sep 1973
TL;DR: In this article, the definition of oil and gas exploration permit areas and offshore boundaries in the North American Datum has been investigated, and the effect of distortions in the system of coordinates known as the 1927 North American Data System (NADS).
Abstract: Because of 1) the appreciable distortions in the system of coordinates known as the 1927 North American Datum, 2) the definition of oil and gas exploration permit areas and offshore boundaries in t...
TL;DR: In this paper, the G1 distributions over some models of topographic relief are evaluated and it is concluded that, although G1 sometimes amounts to a great quantity in mountainous regions, the Molodenskii correction is practically not necessary in computations of gravimetric geoidal height, but on the other hand, it should be taken into account in computation of the deflection of the vertical.
Abstract: Molodenskii's solution of the geodetic boundary-value problem is approximately derived by computing G1, a kind of terrain correction to the gravity anomaly. In the present paper, the G1 distributions over some models of topographic relief are evaluated. It is concluded that, although G1 sometimes amounts to a great quantity in mountainous regions, the Molodenskii correction is practically not necessary in computations of gravimetric geoidal height, but on the other hand, it should be taken into account in computations of the deflection of the vertical.
TL;DR: In this article, a system of equations is derived and computational routines are outlined that can be used to determine the geodetic coordinates and elevation of a point by 3D intersection using horizontal and vertical angles only.
Abstract: Systems of equations are derived and computational routines are outlined that can be used to determine the geodetic coordinates and elevation of a point by three-dimensional intersection using horizontal and vertical angles only. Equations are similarly derived and a computational routine is outlined that can be used to compute the geodetic coordinates and elevation of a point using horizontal angles, vertical angles, and slope distances. In both cases angles are used that have been measured from two or more points having known geodetic coordinates and elevations to a point of unknown position. All data consist of direct field measurements in the form of horizontal angles, vertical angles, and slope distance corrected only for refraction. The equations are exact with respect to a reference ellipsoid, but corrections may be required wherever the actual topographic surface differs significantly from the surface of the reference ellipsoid.
Journal Article•
TL;DR: In this article, the authors present a world-wide coordinate system for the transverse mercator projection by 2 deg width zones, which would be ESPECIALLY useful for CAD, CADASTRAL, and ASSOCIATED PURPOSES.
Abstract: THE FUNDAMENTALS OF COORDINATE SYSTEMS AND THEIR USEFULNESS ARE PRESENTED. BRIEF MENTION IS MADE OF TWO TYPES OF COORDINATE SYSTEMS IN USE -- THE STATE PLANE COORDINATE SYSTEMS AND THE UNIVERSAL TRANSVERSE MERCATOR (UTM) SYSTEM. THE NEED FOR KEEPING DATUM DISTYANCES AND DISTANCES ON THE GROUND IN AGREEMENT -- WITHIN SMALL INHERENT DIFFERENCES -- IS STRESSED. THE PRINCIPLES OF APPLICATION ARE GIVEN FOR THE PROPOSED WORLDWIDE COORDINATE SYSTEM, WHICH COMPRISES A TRANSVERSE MERCATOR PROJECTION BY 2 DEG WIDTH ZONES. THE SYSTEM PRESENTED WOULD BE ESPECIALLY EFFECTIVE FOR ENGINEERING, CADASTRAL, AND ASSOCIATED PURPOSES, AS WELL AS FOR MAPPING LARGE AREAS AT SMALL SCALE. /AUTHOR/
01 Jan 1973
TL;DR: In this article, several significant extensions to the AFCRL program SAGA (Short Arc Geodetic Adjustment) have been implemented and tested, such as improved corrections for tropospheric refraction, capability of exercising on option the precise NWL ephemeris as defined by minute vectors, automatic detection and removal of cycle count errors, an option for processing Geoceiver observations as if they were Intermittently Integrated Doppler (IID) observations, and an option to exercise base line constraints expressed in terms of geodesic azimuths and distances.
Abstract: : Several significant extensions to the AFCRL program SAGA (Short Arc Geodetic Adjustment) have been implemented and tested. These include: improved corrections for tropospheric refraction; capability of exercising on option the precise NWL ephemeris as defined by minute vectors; automatic detection and removal of cycle count errors; an option for processing Geoceiver observations as if they were Intermittently Integrated Doppler (IID) observations; an option to exercise base line constraints expressed in terms of geodesic azimuths and distances; an option to define the coordinate system of the tracking net by means of G. Blaha's 'Inner Adjustment Constraints'; an option to recover relative timing synchronization between stations independently of satellite timing signals; extension of the orbital integrator to accommodate an earth potential defined by spherical harmonics of arbitrarily high degree and order (n,m). By virtue of these extensions SAGA has become a more accurate and more versatile tool for satellite geodesy. (Author)
TL;DR: In this paper, the authors proposed a method of converting geodetic coordinates from a local reference system into the standard Earth on having known the coordinates of at least one station in common with the considered systems.
Abstract: The method of converting geodetic coordinates from a national geodetic reference system into the standard Earth on having known the geodetic coordinates of at least one station in common with the considered systems, is described in detail; the orientation of the Standard Earth at the initial station of the national geodetic reference system, is also determined side by side. For illustration, use has been made of the known coordinates of the Baker-Nunn station at Naini Tal, in India, being in common with the Indian Everest Spheroid and the Smithsonian Institution Standard Earth C7 system (Veis, 1967). The method advocated is likely to be more precise than the existing ones as it does not assume the parallelism of axes of reference between the Standard Earth and the national geodetic reference systems which may not necessarily hold good in actual practice.
01 Jan 1973
TL;DR: In this article, a world-wide applicable technique for recovering vertical deflections at sea using the astrogeodetic technique has been developed, which involves using the difference between the astronomic source, the Integrated Inertial System and Star Tracker, and the geodetic source, NAVSAT as basic measurements.
Abstract: In this paper a world-wide applicable technique for recovering vertical deflections at sea using the astrogeodetic technique has been developed. It involves using the difference between the astronomic source, the Integrated Inertial System and Star Tracker, and the geodetic source, the NAVSAT as basic measurements. Then a spatial interpolation technique is applied to the spatially dispersed basic measurements to estimate vertical deflections everywhere in the area. Optimal Kalman smoothing involving star tracker damping and EM Log damping is applied to improve estimation capability for post test time applications. The technique was evaluated theoretically and empirically in an at-sea test performed on the U. S. Vanguard which contained all the required navigation devices.
01 Feb 1973
TL;DR: In this article, the relationship between one particular S-193 measurement and the parameter of interest for determining the sea surface scattering cross-section is considered, and results are presented for system analyses pertaining to signal-to-noise ratio, pulse compression threshold behavior, altimeter measurement variance characteristics, desirability of onboard averaging, tracker bandwidth considerations, and statistical character of the altimeter data in relation to harmonic analysis properties of the geodetic signal.
Abstract: For the Skylab S-193 radar altimeter, data processing flow charts and identification of calibration requirements and problem areas for defined S-193 altimeter experiments are presented. An analysis and simulation of the relationship between one particular S-193 measurement and the parameter of interest for determining the sea surface scattering cross-section are considered. For the GEOS-C radar altimeter, results are presented for system analyses pertaining to signal-to-noise ratio, pulse compression threshold behavior, altimeter measurement variance characteristics, desirability of onboard averaging, tracker bandwidth considerations, and statistical character of the altimeter data in relation to harmonic analysis properties of the geodetic signal.
01 Jun 1973
TL;DR: In this paper, the use of surface layer techniques, the discrete value approach, and the development from Green's theorem are discussed, the latter being extended to order e cubed in the height anomaly.
Abstract: Procedures for obtaining position from surface gravity observations are reviewed and their relevance assessed in the context of the application of modern geodetic techniques to programs of Earth and ocean physics. Solutions based on the use of surface layer techniques, the discrete value approach, and the development from Green's theorem are stated in summary, the latter being extended to order e cubed in the height anomaly. The representation of the surface gravity field which is required in order that this accuracy may be achieved is discussed. Interim techniques which could be used in the absence of such a representation are also outlined.