(7)  
Azimuth synchro signals are applied from the antenna to the indicator. The sin 0 cos 0 converter resolves the azimuth signal into sin and cos components which are integrated and used to produce vertical and horizontal sweep currents in the deflection coils of the display tube. A range gate generator accepts the radar master trigger and signals from the RANGE switch to provide timing signals to the sweep generators, an unblanking signal to the display tube, and a control signal to the range marks generator. The range marks are combined with the radar video in the video amplifier.

 B. Functional Description, Antenna Stabilization (Fig. 4)
 (1)  
The antenna is motor-driven in elevation, azimuth, and roll. The azimuth motor runs continuously while the system is operating and acts through a cam drive mechanism which causes the antenna to sector scan at a constant rate from 90 degrees left and right of the straight ahead position.

 (2)  
The elevation axis is normally driven by the pitch stabilizing synchro signals from the INS, keeping the antenna level during normal flight regimes. The tilt control signal from the control panel allows the elevation to be increased or decreased from level. The azimuth axis position is resolved and combined with the elevation motor drive to keep the antenna stabilized through its travel.

 (3)  
The roll axis motor is driven in response to the INS roll altitude synchro data, to keep the antenna perpendicular to the ground.

 (4)  
When the MAP mode is selected at the control panel, waveguide components in the antenna shift to feed the antenna with a horizontally polorized RF beam. This causes a spoiler mounted on the reflector to distort the transmitted energy into a cosecant-squared pattern to facilitate ground mapping. Selecting the NORM or CONT modes reverts the antenna to the normal pencil beam configuration.

 EFFECTIVITY

 AT ALL; AZ ALL; LH ALL;  CONFIG 1 AF 157, 161;  03 Page 10 IB406 THRU 499  Sep 25/94

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TO INDICATOR NO. 2

Weather Radar System Display Block Diagram
Figure 3 (Sheet 2)

EFFECTIVITY AT ALL; AZ ALL; LH ALL;
CONFIG 1 AF 157,161; IB 406-499799 Page 12
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MASTER TRIGGER
DISPLAY TUBE
PPI-1L RADAR INDICATOR (NO. 1)
Weather Radar System Display Block Diagram
Figure 3 (Sheet 3)

EFFECTIVITY
CONFIG 1 AF 157,161; AZ 201-224
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 E40009
..XA

AT ALL PPI-1N DIGITAL CIRCUIT RADAR INDICATOR
1
Weather Radar System Display Block Diagram
Figure 3 (Sheet 4)

EFFECTIVITY
AT ALL; LH ALL;

CONFIG 1
IB 406-499;

7XA Page 14AZ 231-280
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..XA

PPI-1T COLOR RADAR INDICATOR
Weather Radar System Display Block Diagram
Figure 3 (Sheet 5)

EFFECTIVITY
 CONFIG 1 AZ 225-229, 281-299
7XA Page 15
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....XA

RECEIVER/TRANSMITTER ANTENNA

FROM INS
Weather Radar Antenna Stabilization Block Diagram
Figure 4

EFFECTIVITYAT ALL; AZ ALL; LH ALL;
CONFIG 1AF 157,161; IB 406-499703 Page 16
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 (5)  The elevation axis is normally driven by the pitch stabilizing synchro signals from the INS, keeping the antenna level during normal flight attitudes. The tilt signal control is from the control panel, which allows the elevation to be increased or decreased from level. The azimuth axis position is resolved and added to the elevation motor drive to keep the antenna stabilized throughout its travel.
 C. Functional Description, Self-Test and Fault Monitoring (See figure 5.)
 (1)  
The self-test features incorporated in the system provide a means of evaluating system performance, on the ground or while airborne, with only momentary interruption to normal system operation. When the weather radar is in the TEST mode, a special test pattern is generated for evaluation of the system. In addition, the system incorporates fault isolation circuitry which provides visual indication, on the receiver-transmitter unit front panel, of an existant malfunction within the system. The outputs of the fault isolation circuits are also applied to the indicator when in the TEST mode. If a malfunction exists, the test pattern is altered to alert that one or more of the fault lamps are illuminated. By utilization of the internally generated test pattern together with the outputs of the fault isolation circuitry, the system is capable of detecting most system malfunctions without additional test equipment.

 (2)  
When the TEST mode is selected, all parts of the system are energized and the transmitter is connected through an external waveguide switch to a dummy load. In the TEST mode the following events will initially occur in addition to the special video test signals:
　
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