(c)
The duplexer couples the transmitter output signal to the waveguide. The duplexer is monitored by power monitor circuits that develop a loop error signal to correct for output frequency variation and noise. The output signal is transmitted by a waveguide to the antenna and then radiated out the antenna flat plate radiator.
(d)
The reflected signal is received by the antenna during the interval between transmission pulses, and applied through the duplexer to the receiver circuits of the R/T. The limiter protects the receiver from power pulses, allowing low power received signals to the mixer in the receiver.
EFFECTIVITY
AF 160, 162-171, 183, 184 CONFIG 4 01 Page 25 Sep 25/9434-43-00
MESSAGE SLOT 6,7,8,9 -LRU FAULTS (BLUE)
(BLUE)
MESSAGE
SLOT 4 - COLOR BAR
MESSAGE SLOT 3
RANGE (BLUE)
GREEN MESSAGE SLOT 5 YELLOW
RANGE MARK INTERVAL
RED RANGE MARK
AZIMUTH MARK
MESSAGE SLOT 10 - SYSTEM GAIN (MAP MODE ONLY) (BLUE) MESSAGE SLOT 14 -TILT (BLUE)
MESSAGE SLOT 13 -STABILIZATION STATUS (BLUE) MESSAGE SLOT 11 -
MESSAGE SLOT 12
TARGET IDENTIFICATION OR CLUTTER SUPPRESSION (BLUE) SYSTEM
1
BLANK FOR SYSTEM 1
Weather Radar Indicator Alphanumeric Displays
Figure 4 (Sheet 1)
EFFECTIVITY
CONFIG 4
AF 160,162-171
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MESSAGE SLOT 2 -
MESSAGE SLOT 1 -
FAULT AND ALERTS (YELLOW)
STABILIZATIONMESSAGE SLOT 6 -STATUS (BLUE)
GROUND CLUTTER SUPPRESSION (BLUE)
BLANK FOR SYSTEM 1
Weather Radar Indicator Alphanumeric Displays Figure 4 (Sheet 2)
E39754
EFFECTIVITY
CONFIG 4
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(e)
The mixer uses a frequency source oscillator to develop the first IF frequency. The first IF amplifier provides a 25 dB gain. The second IF is mixed with frequency source oscillator signals. The second IF amplifier gain is controlled by the automatic gain control (AGC) and sensitivity time control (STC) circuits in the azimuth filter.
(f)
The reflected signal is routed through the duplexer, limiter and the receiver section, and sent to the range filter. The range filter produces digital range samples and applies them to the azimuth filter and the ground clutter processor.
(g)
The range filter is a low-pass filter that also digitizes the signal. The low-pass function improves the signal-to-noise ratio of the IF signal. The digitized signal is sent to the azimuth filter, which filters and encodes the signal. The encoded signal is sent to the input/output circuits, and formatted into a 1536-bit data word. A 64-bit control word is added to the data word and sent to the indicator, in serial form.
(h)
The azimuth scan filter filters the range samples over multiple PRF samples and averages the returns for each range. It also develops STC and AGC gain control signals for the receiver. Display data is extracted from the returns, filtered, and routed to the indicators.
(i)
The ground clutter processor determines whether ground clutter is present. If present, a discrete is sent to the signal encoder which removes the ground targets from the display when the GCS mode is operative.
(j)
In the signal encoder the processed signals are encoded into 3-bit bin display data, routed to the left and the right ARINC 453 line drivers, and sent serially to the left and the right indicators on ARINC 453 data buses 1 and 2. These data buses transmit data at 1 MHz rate. The ground clutter supression circuit operates for all ranges in conjunction with any weather mode.
(k)
The switches controlling mode, range, tilt, turbulence detection, ground clutter suppression and system selection are applied through the control buses to the control word generator in the central processing unit (CPU) of the R/T. The CPU uses the control words to configure the operating parameters of the system. The CPU incorporates a microprocessor to perform its various internal functions. The microprocessor executes its control program, which consists of seven major control routines, 180 times a second.
(l)
The seven major control routines are: 1) Attitude routine providing pitch and roll parameters for the stabilization routine. 2) Stabilization routine providing elevation position to the
elevation maintenance routine. 3) Scan maintenance routine providing antenna scan drive. 4) Elevation maintenance routine providing antenna elevation
drive.
EFFECTIVITY
AF 160, 162-171, 183, 184 CONFIG 4 01 Page 28 Sep 25/9434-43-00 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：747飞机维护手册AMM CHAPTER 34 - NAVIGATION 第34章导航3(109)
