In this chapter, we are going to learn about the Radar Display and the different types of display systems used in the radar system to display the received video signal.
When Radar was first used by the military, the information it provided was displayed on a single unified console. The console included a radar indicator (“Scope”) and its associated controls, and a number of receiver and transmitter controls.
As time passed, the displaying of radar information began to get complicated. Sometimes information from the same radar needed to be displayed in more than one way at the same time so it’s become difficult for a single display to analyze all information.
The device used to display radar information is known as a Radar Indicator or Radar Display.
There are two basic methods of displaying information on a CRT(Cathode ray tube)
- Deflection-Modulated CRT: In this method, targets are identified by the deflection of the electron beam.
- Intensity-Modulated CRT: In this method, targets are identified by intensifying the beam and presenting a luminous spot on the face of CRT.
Now we are going to discuss the Radar Displays one by one in a detailed manner.
Learn Also: Radar Basics, Types of Radars and Its application
- A scope display presents only the range to the target and the relative strength of the echo.
- Such a display is normally used in weapon control radar systems.
- The A-scope display normally uses an electrostatic deflection CRT.
- Applying a sawtooth voltage to the horizontal deflection plates produces the sweep.
- The electrical length of the sawtooth voltage determines the total amount of range displayed on the CRT face.
- A-scope is a deflection modulated rectangular presentation in which the vertical deflection is proportional to the amplitude of the received echo power and the horizontal coordinates represent the range as per the time delay.
- An intensity-modulated rectangular display with azimuth angle indicated by the horizontal coordinates and range by the vertical coordinates.
- An intensity-modulated rectangular display with azimuth angle indicated by the horizontal coordinates and elevation angle by the vertical coordinates.
- A C-scope in which the blips are extended vertically to give a rough estimate of distance.
- An intensity-modulated rectangular display with distance indicated by the horizontal coordinates and elevation angle by the vertical coordinates.
- A rectangular display in which the target appears as a centralized blip when the radar antenna is aimed it.
- Horizontal and vertical errors are respectively indicated by the horizontal and vertical displacement of the blip.
- A rectangular display in which the target appears as a laterally centralized blip when the radar antenna s aimed as t in azimuth and wings appears to grow on the pip as the distance to the target is diminished.
- Horizontal and vertical aiming errors are respectively indicated by the horizontal vertical displacement of the blip.
- The PPI scopes are by far the most used radar display.
- It is a polar coordinate display of the area surrounding the radar platform.
- Own position is represented as the origin of the sweep, which is normally located in the center of the scope but may be offset from the center on some sets.
- PPI uses a radial sweep pivoting about the center of the presentation.
- This results in a map-like picture of the area covered by the radar beam.
- The basic PPI screen presentation results from the raw video.
- The raw video provides only a blip on the indicator screen, leaving the target interpretation entirely to the operator.
- PPI is an intensity modulated having circulator representation or display n which echoes are in two coordinates i.e. range and Azimuth in polar coordinates.
To know more about the PPI(Plan Position Indicator) Display you can read the below topic:
PPI Display with function block diagram
Range-Height Indicator (RHI)
- The range-height indicator (RHI) scope, is used with height finding search radars to obtain height information.
- The RHI is a two-dimensional presentation indicating the target range and height.
- The sweep originates in the lower left side of the scope.
- The bottom horizontal line indicates the line of sight to the horizon.
- All information’s shown on a digital monitor.
- If you mark a target with the cursor, then additional information is represented as a full data block.
- A permanent representation of the additional information also can be chosen, but this gets too confused for a longer time.
Beta Scan Scope
- A precision approach radar found information shown in Beta Scan Scope.
- In the figure that is two pictures: The upper is a side view of the landing approach up to the touchdown point on the runway with the imaginary line as reference.
- This upper picture shows the data determined by the antenna to the height scanning. It is also called an Elevation picture, therefore.
- The top view of the imaginary prolongation of the centerline of the runway, the touchdown, and the range marks is corresponding to the lower picture.
- This lower picture shows the data recorded by the antenna to the horizontal sector scanning. It is also named as Azimuth picture, therefore.
Flat Panel Display
There is some displays system which is being used for the radar also, such as Flat panel display, but all are not suitable for radar.
Various types of FPDs are given Below:
The liquid Crystal Display (LCD) :
- It has been used for non-radar applications low weight, volume, and power consumption are important in laptop computers, watches, instruments, calculators, etc.
- The LCD does not emit light of its own but operates by controlling the light that either passes through it or reflects on it.
- Normally the light is directed from the back and the display is said to be backlit.
- There are two types of LCDs:
- The Passive matrix LCD
- The active matrix LCD
- The active matrix LCD has higher resolution, and better image quality, it can be displayed in color and has a faster response. Thus the active MCD has more potential for radar application than does the passive matrix.
The Plasma Display:
- Other types of FPDs are the plasma display which can produce large flat full-color displays, electroluminescent displays, light emitting diodes, and field emitter displays.
- FPD such as AM LCDs and the plasma display have several important advantages over conventional CRTs. They are smaller, lighter, occupy less volume, and require less power than CRTs.
- In addition, they are expected to have better reliability and reduced life cycle cost.
- The FDD is especially well suited for cockpit display in military airborne applications and is replacing the CRT in many air-borne systems.
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