- Branche: Earth science
- Number of terms: 93452
- Number of blossaries: 0
- Company Profile:
Founded in 1941, the American Congress on Surveying and Mapping (ACSM) is an international association representing the interests of professionals in surveying, mapping and communicating spatial data relating to the Earth's surface. Today, ACSM's members include more than 7,000 surveyors, ...
(1) An instrument determining radial velocity of an object by comparing the frequency of radiation returned from an object with the frequency of radiation transmitted toward the object. e.g., Doppler radar on an aircraft determines the velocity of the aircraft, referred to a coordinate system on the aircraft, by measuring the Doppler shift experienced by microwaves transmitted towards the Earth and scattered back to a receiver at the aircraft. The radio waves are transmitted as suitably oriented beams. At least three beams are required; a fourth beam has recently been added (in radars operating coherently) for a check. The term Doppler radio system is preferable, since the so called Doppler radar is not, properly speaking, radar. (2) An instrument which determines the radial velocity of an object by comparing the frequency of radiation received from the object with the known frequency of the radiation emitted by it. This type of Doppler radar has been used for determining the trajectories of spacecraft sent to other planets, etc. The term is also applied to equipment and apparatus incorporating an instrument of either of the types described in the definitions. The term Doppler radio system is preferable, since the so called Doppler radar is not, properly speaking, radar.
Industry:Earth science
The correction applied to a measured depth to take into account the difference between the draft of the ship when moving and the draft when motionless.
Industry:Earth science
An apparatus for applying tension to a surveyor's tape and consisting basically of a lever having two arms, one short and one long, at an oblique angle to one another. The lever is pivoted at the junction of the two arms. The pivot moves in a slide. A weight is hung from the end of the long arm and one end of the tape is attached to the end of the short arm.
Industry:Earth science
A self-contained apparatus transmitting two or more beams of electromagnetic or acoustic energy downward toward a reflecting surface and using the change in returned frequency (caused by the motion of the vehicle) to measure the speed of the vehicle with respect to the reflecting surface.
Industry:Earth science
(1) An ellipsoidal body which has the same mass and the same rotational velocity, about the shortest axis, as the Earth and the same value of the coefficient C2 ( J2) in the representation of the Earth's gravity potential by a Legendre series. (2) An ellipsoidal body whose surface is at constant potential and whose four defining constants are determined by an adjustment of more than four interrelated constants. e.g., the values for the mass of the Earth, gravity at the equator, flattening, potential on the geoid, equatorial radius, and the ratio of the gravitational force to the potential on the geoid have been determined simultaneously, even though only four of them are independent. (3) That ellipsoid which most closely approximates the geoid.
Industry:Earth science
The material that moves more or less parallel to the shore-line under the influence of oceanic forces.
Industry:Earth science
A right acquired by an adverse user to use the land of another.
Industry:Earth science
An easement lying outside the parcel of land being conveyed but of benefit to the parcel.
Industry:Earth science
The graphic record produced by an echo sounder and showing, as a function of time, the strength of the echo and the time taken for the echo to return. If the ship's velocity is constant, the echogram is a distorted profile of the bottom or, if the sound penetrates the bottom for a considerable distance, a distorted cross section of the underlying layers.
Industry:Earth science
