Aviation Electronics Technician 1 - Historic Naval Ships Association

Mode SwitchThe mode switch is practically self-explanatory.In the trainer, this switch sets up one of the basicoperating modes available, such as search, bombdirector, or fire control.Receiver Gain ControlThe receiver gain control is one of the mostimportant controls available to the operator, whetherthe pilot in the aircraft or an operator on a trainer.This control, if not properly adjusted, will prevent theentire system from operating at peak performance.Some radar systems include a built-in test function,which provides a reasonable check of the adjustmentof the receiver gain control. This control is normallyadjusted for best definition of the weakest targetavailable. There is only one acceptable method foradjusting this control to obtain peak detection, whichprovides maximum range. In each particular radar,this method is part of the minimum performance test.Antenna Control (Hand Control)The hand control of an actual radar installationallows the operator to select manual search operationand selection of targets. Through the use of thiscontrol, the operator may command the radar toacquire and/or release the target. The 11D13A hastwo controls, one for azimuth and one for range.During automatic search, these controls have twofunctions---(1) to position the antenna in elevationand azimuth, and (2) to select the area to be searchedin relation to the horizon. You can see that thesecontrols and the receiver gain control are veryimportant because they will affect target detectionperformance.INDICATOR DISPLAYSA description of the indicator displays (PPI orB-scope) in the three basic modes of operation and thesubmodes of fire control is given in the followingparagraphs. The indicators are used to monitorsystem performance during simulated operation in allweather conditions.Basic SearchIn the basic search mode, information is displayedon the PPI only. As shown in figure 3-10, the PPIscan presentation may be a maplike picture of theearth’s surface being seamed. The range sweep linerotates in synchronization with the antenna through afull 360-degree cycle. Targets appear on the face ofthe CRT as an intensified light spot. The range of thetarget is indicated by its position on the radius of therange sweep line, and target azimuth position isindicated by the angle of the sweep line at the time thetarget is painted. The top of the scope is 0 degree, andmay indicate dead ahead.If 1,000-yard marks are selected, the two rangemarks shown in the figure are 1,000 yards apart. Thefirst range mark, which starts from the center of thescope and moves outward toward the edge of thescope face, indicates targets from zero to 1,000 yards.There are two targets shown in figure 3-10 that arebetween the 1,000- and 2,000-yard marks. Othertargets are shown at greater ranges and at differentThe hand controls have complete control of theantenna during manual search, and, in addition, alsocontrol the acquisition symbol to acquire the target.Auxiliary ControlsThrough the use of a scan switch in an operationalradar, the operator may select either full azimuth orsector scan. The trainer, likewise, incorporates a scanswitch that may be used to select the type of scandesired. In the trainer, the selections are automaticsweep at a 6-RPM rate, variable sweep from zero to 6RPM manually controlled, or sector scan.Figure 3-10.-PPI scan presentation basic search.3-11