AEROGRAPHER'S MATE 3 & 2 



range markers,, The range markers may be 

 turned on or off and may be varied. 



Factors Affecting Radar 

 Performance 



There are many factors, or elements, that 

 affect efficient radar performance, not all of 

 which are completely understood. M;iny of the 

 limitations of the equipment are a result of radar 

 design. 



RADAR SET AN/FPS-81 



Meteorological Radar Set AN/FPS-81 is a 

 ground-based radar system used to establish the 

 geographic locations of storm centers relative 

 to a fixed base reference site. The equipment 

 is capable of detecting storm centers within 

 a radius of 200 nautical miles. Radar echo sig- 

 nals from concentrations of high moisture con- 

 tent are presented on cathode-ray tube (CRT) 

 indicators in such a manner as to convey the 

 positions of storms in terms of azimuth, slant 

 range, and elevation (height). The radar echo 

 signals may be displayed with iso-echo con- 

 touring, if desired, to provide maximum clari- 

 fication of storm configurations. 



Limitations 



The antenna may be made to scan manually 

 in both planes (azimuth and elevation) simulta- 

 neously, or it will scan automatically in one 

 plane while manual search is conducted in the 

 other. The antenna will not scan automatically 

 in both planes simultaneously. Radar targets will 

 not normally be visible at less than a 1-mile 

 range. 



Component Parts 



Meteorological Radar Set AN/FPS-81 con- 

 sists of an antenna assembly, a Receiver-Trans- 

 mitter-Modulator (RTM) assembly, an indicator 

 console, and a remote indicator assembly. (See 

 fig. 6-3.) The major portion of the system cir- 

 cuitry is contained in modular units of the plug- 

 in type to simplify and expedite maintenance 

 procedures. 



ANTENNA ASSEMBLY. — (fig. 6-3 (D)) Radar 

 illumination of target areas is provided by the 

 antenna which directs and concentrates the 

 high-level RF (radiofrequency) energy into a 

 narrow beam. Radar echoes are returned from 



target areas to be detected by the antenna 

 and fed to circuits throughout the system. 



Control of the antenna may be accomplished 

 manually or automatically. 



RECEIVER-TRANSMITTER-MODULATOR 

 (RTM) ASSEMBLY. — The receiver-transmitter 

 assembly (fig. 6-3 (C)) contains the electronic 

 components required to transmit and receive 

 the RF signals. 



INDICATOR CONSOLE. — The indicator con- 

 sole, from which the entire system may be 

 controlled and monitored, houses the Range/ 

 Height Indicator (RHI), the Plan Position In- 

 dicator (PPI), and the Range Indicator as 

 illustrated in figures 6-3 (A) and 6-4. 



A power panel on the rear of the indicator 

 console, mounted between the PPI and .range 

 indicator assemblies, accepts power for distri- 

 bution to the entire system. 



PLAN POSITION INDICATOR (PPI). — The 

 PPI, located in the center portion of the indicator 

 console, presents range and azimuth informa- 

 tion in a plan view (as seen from zenith di- 

 rectly over the radar site). 



RANGE/HEIGHT INDICATOR (RHI). — The 

 RHI indicator occupies the left side of the in- 

 dicator console and presents range and height 

 information. 



RANGE INDICATOR. — The range indicator, 

 housed in the upper right-hand section of the 

 indicator console, features a standard A-scan 

 tube. Range information (A-scan) is displayed 

 along the horizontal axis of the CRT display. 



REMOTE INDICATOR. — The remote indicator 

 assembly, figure 6-3 (B), which may be lo- 

 cated away from the indicator console, pro- 

 vides a repeat display of the information 

 presented by the local indicator. 



RADAR SET AN/FPS-106 



Meteorological Radar Set AN/FPS-106(V) is 

 the newest of the Navy weather radars. It can 

 be installed both at fixed locations and in mobile 

 vans to detect and plot movements of storms 

 and other meteorological phenomena. The operat- 

 ing range is to 200 miles with an azimuth scan 



104 



