Chinese English

A depiction (photographic reproduction or drawing) of appearance of LANDMARKS on the PPI scope of a radar set at a particular geographic location, inten­ded to facilitate the identifica­tion of the COAST. This can aid the navigator to identify or match his own radar image of these same LANDMARKS.

A straight line extending outward from a cen­tre. In PHOTOGRAMMETRY, a line or direction from the RADIAL CENTRE to any point on a PHOTOGRAPH. The RADIAL CENTRE is assumed to be the PRINCIPAL POINT, unless otherwise designated (e.g., NADIR RADIAL). See also ISORADIAL.

In PHOTOGRAM­METRY, the selected point on a PHOTOGRAPH from which RADIALS (directions) to various IMAGE POINTS are drawn or measured (i.e., the origin of RADIALS). The radial centre is either the PRINCIPAL POINT, the nadir point, the ISOCENTRE, or a SUBSTITUTE CENTRE.

The aerotriangulation procedure, either graphical or analytical, in which directions from the RADIAL CENTRE, or approximate RADIAL CENTRE, of each overlapping PHOTOGRAPH are used for horizontal-control extension by the successive INTERSECTION and RESECTION of these direction lines. A radial triangulation also is correctly called a radial plot or a minor-control plot. If made by analytical methods, it is called an analytical radial triangulation. A radial triangulation is assumed to be graphical unless prefixed by the word analytical.

在空中三角测量中，无论是解析法或图解法，均利用自每一重叠像片辐射中心或近辐射中心绘出的方向线，通过这些方向线的前方交会和后方交会进行水平控制加密。准确地说，辐射三角测量应称作radial plot （辐射图解测量）或minor-control plot（次等控制展点）。假如通过解析法进行，则称为解析辐射三角测量。辐射三角测量一般均指图解法，除了预先注明为解析法的以外。

Communication by ELECTROMAGNETIC WAVES, without a connecting wire. A RADIO RECEIVER. Sometimes called wireless particularly in British terminology.

Determining distance by a combination of RADIO and SOUND, the RADIO being used to determine the instant of transmission or reception of the SOUND, and distance being determined by the TIME of transit of SOUND, usually in water. Also called radio acoustic sound ranging. See DISTANCE FINDING STATION, ECHO RANGING, SONOBUOY.

由无线电和声波相结合进行距离测定。无线电用于确定声信号发射和接收的时刻，距离则通过声信号（通常在水中）传播的时间来确定。亦称 radio acoustic sound ranging（无线电水声测距）。参见distance finding station（测距台），echo ranging（回声测距），sono-buoy（声呐浮标）。

A RADIO TRANSMITTER which emits a di­stinctive or characteristic SIGNAL used for the deter­mination of BEARINGS, COURSES or location. One inten­ded to mark a specific location is called MARKER BEACON.