曝光台 注意防骗
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MAP
Pushing the MAP pushbutton switches the R/T unit to the ground mapping
mode, and terrain features will be shown on the EHSI.
TEST
The test mode is selected by pushing the TEST pushbutton. In the TEST
mode a test pattern and the system status messages will be shown on the EHSI.
( NOTE:The TEST, WX , WX+T ,and MAP pushbuttons are electronically
interlocked.Only one of the four modes can be selected at any one time.)
IDNT
This pushbutton turns on ground clutter suppression to reduce ground clutter
in WX and WX+T modes. Selection of the MAP mode turns off clutter
suppression.
STAB
Stabilization is turned on by pushing the STAB pushbutton. With
stabilization on ,the antenna stabilization is provided by the IRS through the R/T
unit.
(To turn off IDNT or STAB, the respective switch must be pushed for a
second time).
[4] The weather radar antenna radiates a narrow pencil beam and receives the
reflected pulses. The drive mechanism moves the antenna back and forth across
the front of the airplane and maintains the sweep parallel to the horizon at the
angle selected on the control panel. The antenna pedestal and the 28-inch
diameter antenna flat plate make up the X -band antenna assembly.
Fig. 29-3 antenna/waveguide assembly
[5] The antenna flat plate is a phased array radiator with a gain of 35 db. The
radiated beam is 3.5 wide and 3.6 high . The antenna pedestal provides drive
for the antenna flat plate and also provides feedback to the R/T unit. The
antenna scans 90 parallel to the horizon at a scan rate of 50 per second.
Antenna tilt is selected by the tilt control on the WXR control panel .The
antenna scan and tilt are controlled by a dedicated microprocessor inside the RT
unit. The flat plate is driven by stepper motors via a gear drive. Scan and
elevation disable switch are located inside the left antenna pedestal cover.
[6] The WXR waveguide provides the means of sending transmit and receive
RF signals between the R/T and the antenna. There are two waveguide sections
between the R/T unit and the antenna. Section 1 is a rigid waveguide, one end
connects to the section 2 , the other end connects to the antenna by means of a
quick-disconnect clamp. Section 2 is a flexible waveguide between the R/T unit
and waveguide section 1.The elevation zero and incremental monitors provide
antenna elevation position feedback. This feedback signal will be amplified, and
then send to the input/output circuit. The I/O circuit will convert this analog
feedback signal to digital signal format for the microprocessor.
[7] The EHSIs show the weather radar data. WXR data is shown in expanded
NAV, expanded VOR/ILS, MAP and
center MAP modes. The WXR switch on
the EFIS control panel is used to turn on
the weather radar system and to turn on
weather radar display. The radar returns
are processed by the R/T unit .The display
covers an area 90 from the airplane
centerline, and from the airplane symbol to
just below the azimuth arc at the top of
EHSI display. The intensity of the various
types of weather is displayed in different
colors, areas of heaviest rainfall appear in
red, moderate levels of rainfall in yellow,
and light rainfall in green. Turbulence
information is shown using magenta.
[8] If the EHSI starts to overheat when
weather data is being shown, the EFIS
symbol generator removes the weather
radar display and shows an overheat
message.
EXERCISE
A. Find out the explanations of the following words in your "English-chinese
technical dictionary"
1. calibrate [ P1-25 ]
2. interlock [P1-83 ]
B. Translate lesson 29 1st, 2nd, 4th and 5th paragraphs into chinese.
C. with the help of figure 29-2, describe the functions of the WXR control panel
(in chinese).
Fig. 29-4. WXR display
READING MATERIAL
LESSON 30
PITOT / STATIC SYSTEM
VOCABULARY
1. pitot/static system ['pitou]/['stætik ] 全静压系统
2. dynamic [ dai'næmik ] a. ; n. 动态的;动态
3. interfacing [ 'intfeisi ] 连系;连接
4. probe [ proub ] n. 探头
5. static port [ 'stætik ][ p :t ] 静压口
6. hose [ houz ] n. 软管
7. line [ lain ] n. 管道;;导管
8. accumulation [ kju:mju'lein ] n. 堆积;聚集
9. alternate [ ' :lt:neit ] a. 备用的
10. standby [ 'stænd'bai ] a. 备用的
11. outside [ 'aut'said ] a. 外部的prep. 在…的外边
12. control cabin 驾驶舱
13. heat module [hi:t ]['m dju:l ] 加热组件
14. project [ 'pr d ekt ] v. 伸出;突出
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航空工程英语基础（中英文对照）(48)
