Radar display

A radar screen is a popular term for all types of radar screens (radar indicators) and displays the data that appear to a radar device. It should show a possible, easily understandable, and scale as possible graphical representation of the position of the radar targets in real time. Additional information such as the identifier or ID of the target it will be displayed with, if possible.

There are different types of vision systems:

A -scope

The A -Scope has a one-dimensional representation and displays only the removal of echoes, usually only for one direction. It is the oldest form of visual display unit. With the first radar wanted to detect only the presence and the distance of objects. Thus, an A-scope completely handed. At the moment of sending the electron beam from the left side starts to run, and moves at a constant speed to the right. If the receiver receives an echo of the electron beam is deflected upward. Through the reflections on the bottom one has a lot of noise, which is best seen on the A-scope at close range. The simplest form of the A - Scopes would be an oscilloscope, which is connected to the video output of the radar receiver. (Block diagram A-Scope )

B -scope

When a B -scope (azimuth ) in the abscissa is the azimuthal angle plotted in the ordinate and the distance. This type of vision is preferred in Feuerleitradargeräten.

The azimuth values ​​are mostly by hand wheels slidable ( it is then the entire antenna is rotated into the new direction). The center of the screen is usually then the main reception direction of the antenna. The side angle range is swept by an electromechanical or electronic beam scanning.

C -scope

The C -scope indicates the directions of elevation angle in the y-axis and azimuthal angle in the x-axis. It is a particularly useful representation for goals and was therefore used in fighter planes. However, it could not be fetched distance, so was mostly used in addition to the C -scope a J -scope.

E -scope

The E -Scope was used as height vision device in old analog radar devices. It was the distance in the abscissa and the angle of elevation in the ordinate. The target height could usually be determined with the aid of a nomogram on the visual display unit.

J -scope

The J -scope is an outdated vision device to remove ad in historical radars, for example, in the FuG 212 ( " Lichtenstein" device), the radar in the German night fighter Bf 110 G - fourth, it is an A -scope with a circular Entfernungsauslenkung. Through the circular arrangement of Auslenkstrahls the diameter of the cathode ray tube was about three times better utilized than the A -scope. That brought an improvement in the range resolution and accuracy.

RHI -scope

The RHI -Scope (Range - Height Indicator) has a two-dimensional representation and displays the height and distance of the aircraft for a direction. It was formerly often used together with an A -Scope on landing controller. The RHI -Scope is basically an A -Scope, which moves synchronously with the joint of the antenna, making it feel like it can move up and down. The echoes are shown here as differences in brightness, not like the A-Scope as deflection.

PPI Scope

The PPI -Scope ( Plan Position Indicator) has a two-dimensional view showing the distance and direction for all echoes on. It is the classic form of the viewing device. Through a deliberately long persistence of the screen you can see the last positions of the target ( the so-called " persistence trail ", formed by the slowly decaying light spots of the same portable target, received during the preceding antenna turns). In practice, the " Sweep" (the line the current position of the antenna ) is set so dark that the user no longer sees this just because it only interferes with the long persistence. The sweep visualization practically corresponds to an A -Scope, which rotates about the center and how the RHI -Scope represents the echoes as bright dots.

When PPI -scope with a few exceptions is always up north. However, if the radar driving or airplane bound is (navigation radar), a distinction is also the Head-Up (vehicle longitudinal axis or forward is up), the North -up ( north is up, to compass data must be included in the presentation ) or course -up display, in a selectable azimuth value (typically, the nominal price of the vehicle) is on top and thus possibly a path deviation from the prescribed course is made visible. Furthermore, navigation radars often provide the so-called true motion representation, in which moves the origin of the sweep along the vehicle path on the screen.

An ( analog ) was originally PPIs scope always a cathode ray tube (CRT), to which a rotatable ring is placed, on which a sitting Auslenkspule. The position of the antenna and the position of the coil are in this case be synchronized so that the electron beam is deflected radially synchronously to the transmission pulse from the center of the screen and light controlled during the reception of radar echoes. The distance and direction marks are generated by the same electron beam, which is modulated to its brightness. In most cases the markings are not quite as bright as the echoes whose luminous intensity corresponding to the strength of the received signal. ( Block diagram)

At the time of the radar invention in the Second World War, the German term for such a vision device "star writer ". There was also an optical solution, the so-called " Seeburg table " in the place of the cathode ray tube, a bright sharp light dot was controlled from below on an occupied with a general staff map glass table.

In currently used pixel-oriented or digital displays specific display properties of a classical PPI scopes are simulated ( CRT - based ) by computer algorithms - for example, the representation of the sweep, variable brightness of the displayed range rings and direction vectors and the extra-long, one or more revolutions the radar antenna outlasting afterglow of the phosphor layer used in conventional radar picture tubes. The latter in particular is intended to facilitate for the radar operator, the visual distinction of fixed as opposed to relative to the own vehicle (or position ) moving targets.

Betascan Scope

The Betascan Scope displays the information detected by a precision approach radar in two separate "pictures" to which rectangular coordinates are based. The top image is a side view with the imaginary line of the landing approach to the touchdown point on the runway as a reference line. The picture above shows the data obtained from the antenna to scan in elevation. It is therefore also called Elevation picture. Accordingly, in the lower picture is a top view of the imaginary extension of the center line of the runway, the point of application and the removal brands. This image below shows the data collected from the antenna to the horizontal sector scan. It is therefore also with azimuth image.

Raster scan Scope

The Synthetic display ( or raster scan scope) is a representation of the radar information in the style of a television screen. This form of data display is entirely man-made and includes a single display not only the distance and direction, but also additional information such as the amount of the airborne target, geographic information and virtually any other desired information. Can be switched depending on the design or pure RHI or A -Scope. Through the synthetic representation only a small area can also be easily be switched out and data of other radars, which an arbitrarily large area can be displayed on a display here. When a weather radar is used to display the strength of the cloud color, and so distinguish a thunderstorm from a light rain area. Synthetic displays are produced usually by a computer, which can also provide over a LAN or WAN other computers then this data. For example, some data of the German Armed Forces are also provided by the ATC available.

The Synthetic display will displace the remaining PPI and RHI scopes because of its flexibility in the future. The A -Scope will still continue to exist for some time to assist the technician.