submodes—automatic search, manual search, lock on, automatic track, and breakaway. These submodes parallel the general submodes found in actual weapons control systems. The trainer has no standby mode as such. (The purpose of a standby mode is to apply filament voltages for initial warm-up before selecting an operating mode.) Most radar sets include an automatic time-out (time-delay) circuit, which prevents application of power to the high-voltage sections prior to the necessary warm-up period. Search Mode Search operation for airborne and ground targets is provided with ranges of 0 to 6,000 yards and 0 to 12,000 yards. In this mode the antenna automatically scans the horizon, rotating in a clockwise direction at 6 RPM. Manual control of the antenna in this mode provides manual tracking of detected targets. There are some minor differences in the methods of manual control; however, they are of little consequence. Range marks are selectable in 1,000-, 2,000-, or 3,000-yard increments. In the basic search mode, the B-scope, which is also included in the indicator unit, is deactivated. Fire Control Mode When the fire control mode is selected, the target simulator provides a three-dimensional target (target with range, azimuth, and elevation information). In t h e  f i r e  c o n t r o l  m o d e ,  t h e r e  a r e  f i ve submodes—automatic search, manual search, lock on, automatic track, and breakaway. The five submodes permit the simulated target to be detected initially, manually tracked and acquired, and tracked automatically until minimum range is reached. At this time, a breakaway signal in the form of a large X is displayed on the B-scope indicator, warning the operator to break away from the target. In an actual weapons radar, the breakaway X also means that the aircraft is too close to the target to allow time for an air-to-air missile to properly track the target. Minimum range in fire control operation is 3,500 yards. Three ranges are provided for target information while operating in the fire control mode-0 to 10,000, 0 to 40,000, and 0 to 80,000 yards. During this mode of operation, target information is displayed on both the PPI and B-scope of the indicator display unit. The B-scan display uses a dual-gun arrangement (to be discussed later), which provides steering information in addition to the normal plot display. Bomb Director Mode Operation in the bomb director mode covers the same ranges provided in the fire control mode. Aiming information is displayed on the PPI display. Switching circuits, which are energized at the time of mode selection, cause the presentation to be altered to conform to typical bomb director system presenta- tions. The PPI display has a depressed-center sector scan at twice the scale of the fire control mode. The indicator includes controllable range and azimuth marks (strobes), which act as cross hairs to facilitate aiming (aim point tracking). SYSTEM CONTROLS Through the manipulation  of the basic controls, the operator has available all of the previously mentioned modes of operation. The controls of the trainer are decentralized to simplify construction and operation, but these controls can be grouped into five major categories according to their function. The five major control functions are as follows: 1. 2. 3. 4. 5. Power switch Mode switch Receiver gain control Antenna control (hand control) Auxiliary controls Power Switch The power switch is the system’s off-standby- operate switch. The off position, of course, removes all power from the system. The standby position, as previously described, would apply filament power and keep alive voltage to the TR tubes. For purposes of training, the 11D13A has a power switch for each of the major units antenna transmitter, and so forth). This allows for operation of each of the units or any selected combination of units for training. During the discussion throughout this chapter, the appropriate control will be noted, along with its function and its relationship to one of the four major function controls, if necessary. 3-10