. Aerographer's Mate 3 & 2. United States. Navy; Meteorology; Oceanography. FACE OF TUBE SCALE OF MILES ENGRAVED ON TRANS- PARENT OVERLAY Figure 6-1. — General appearance of A-type scan presentation as it would appear on the range in- dicator CRT. R-Scan Presentation The R-type scan is almost identical to the A-type. The difference between the two is that the A-scan presentation displays the total range starting at 0 range and ending at any one of several ranges selected; the R-scan presenta- tion isolates a portion of the range scale and expands it. PPI-Scope Another type of displ
. Aerographer's Mate 3 & 2. United States. Navy; Meteorology; Oceanography. FACE OF TUBE SCALE OF MILES ENGRAVED ON TRANS- PARENT OVERLAY Figure 6-1. — General appearance of A-type scan presentation as it would appear on the range in- dicator CRT. R-Scan Presentation The R-type scan is almost identical to the A-type. The difference between the two is that the A-scan presentation displays the total range starting at 0 range and ending at any one of several ranges selected; the R-scan presenta- tion isolates a portion of the range scale and expands it. PPI-Scope Another type of display commonly used in radar is termed Plan Position Indicator (PPI). This display makes it possible to read range and bearing information simultaneously. A dia- gram of a basic PPI-scope is shown in figure RANGE MARKS Figure AZIMUTH INDICATOR SCALE •Diagram of PPI-scope. In essence, with the PPI-scope, the sweep starts at the center of the tube instead of at one edge as it does on the A-scope. As the antenna rotates around a 360° circle, the sweep rotates simultaneously. The intensity of the sweep display is modified by the presence of a return signal. Thus, the position of a target is indicated at the correct azimuth and range by a bright spot on the display tube. A map- like picture is thereby produced on the tube as the antenna rotates in the ai'muth plane. RHI-Scope The Range Height Indicator (RHI) is another scope found on radar equipment. Its function is not unlike that of the PPI except that when this scope is used, the azimuth of the antenna is kept fixed while the antenna moves from view- ing at 0° elevation to a predetermined elevation. Range Markers Each of the conventional scopes provides for some direct indication of range by display of 103. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble th
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Keywords: ., bookcentury1900, booksubjectmeteorology, booksubjectunitedstates
