737 AMM 飞机维护手册 导航 NAVIGATION 2(40)

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B.  The receiver-transmitter (R/T) contains the receiver, modulator, TR limiter, duplexer, stabilization, DC power supply, and control circuits. Peak power output from the magnetron oscillator is approximately 125 watts at a frequency of 9330 MHz in the X-band. Pulse length is 2-20 microseconds nominal and the pulse repetition frequency is 180-1440 pps (synchronized to the R/T power supply chopper frequency).
C.  The double conversion superhetrodyne receiver contains a limiter, a mixer, two IF amplifiers, an analog to digital converter, two digital filters and an encoder. The digital filters optimize the bandpass of the receiver for improved signal-to-noise ratio. The encoder is the digital output of the receiver applied to the indicator.
D.  The front panel of the R/T has an overtemperature fault indicator, a fault reset button, and a time indicator. The overtemperature fault indicator monitors the electronic cooling system and must be manually reset. The time indicator displays elapsed operating time in hours.
3.  Waveguide
A.  The waveguide connects the R/T to the antenna. The waveguide is X-band, and is pressurized with cabin pressure and passes through a pressure seal where the waveguide leaves the airplane's pressurized area and enters the nose-cone area. A cover flange connects the waveguide to the R/T. The waveguide connects to the antenna with a choke flange and quick-disconnect clamp.
4.  Indicator
A.  The weather radar indicator is a color indicator that provides a constant, non-fading display of all detectable targets within the scan angle and range selected. The indicator can display weather, weather plus turbulence, or ground maps. The display is generated from the information provided in a 1600-bit serial word, provided by the receiver-transmitter.
B.  The function of the controls on the radar indicator are as follows:
(1)  
PWR - Applies or removes power to the system.

(2)  
WX (weather) - Places radar system in the normal weather detection mode of operation. The indicator shows areas of significant rainfall as colored areas on the display. Terrain such as mountains, etc., may also be displayed.

(3)  
WX/T (weather plus turbulence) - Normal weather detection is made and displayed in the same manner as the weather mode except targets (green, yellow or red), within 50 N.m, containing turbulence will be displayed in magenta.

(4)  
GCS (ground clutter suppression) - Provides ground clutter suppression in WX and WX/T modes.

(5)  
MAP - Provides a terrain map of the area ahead of the airplane. Displays, in green, yellow and red color, prominent features such as cities, mountains, coastlines, and rivers. The system gain is selectable in the MAP mode by the use of GAIN control.

NOTE:  All modes may be used as desired by the operator without adverse effect on the radar system. However, all safety precautions must be observed when the radar is placed in operation on the ground near other airplanes, during defueling/refueling operations.

(6)  
TEST - Activates the test mode for the system. Initially, the transmitter is enabled for less than 1 second to check for proper power generation and then the transmitter is muted for the remainder of the test. A test pattern is generated containing four concentric arcs with magenta, red, yellow, and green displayed from top to bottom. An antenna test sequence is automatically performed. A complete left-to-right scan and up-to-down tilt cycle will occur, with the tilt angle displayed on the indicator.

(7)  
LFT, FWD, RGT push-buttons - Pressing LFT, indicator displays a left view with origin at the bottom right of CRT. Pressing RGT causes a right view to be displayed with origin at bottom left of CRT. Pressing FWD, a forward view is displayed with the origin at the bottom center. The indicator automatically powers on to the forward view.

(8)  
HOLD push-button - when pressed, the image on the display is frozen. When pressed a second time, the hold operation is disabled.

(9)  
RNG push-buttons - Controls the range in nmi on the indicator display. There are five settings 10, 20, 50, 120, 240.

(10)
MKR control - varies the intensity of the range arcs and azimuth lines relative to overall video brightness.

(11)
INT control - Varies the intensity of video on the display.

(12)
STAB push-button - Enables or disables the stabilization to the antenna system from the R/T unit, which receives a signal from the attitude reference system.

(13)
GAIN control - Controls the receiver sensitivity in MAP mode only. In all other modes the sensitivity is automatically controlled.

(14)
TILT control - allows the antenna system to be tilted up or down through 30 degrees (15 degrees in each direction).

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Feb 20/85  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  34-41-02 Page 5 
　
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