RMIT飞行训练课件－ADF Operations ADF操作

航空

游客，如果您要查看本帖隐藏内容请回复

航空

RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 1
ADF OPERATIONS
Aim: To learn the principles behind the operation of the ADF navigation system.
Application:
- orientation (where am I?).
- supplementary navigation information.
Definitions:
 NDB
- Non-Directional Beacon, is the ground radio transmitter that radiates
energy in all directions.
 ADF
- Automatic Direction Finder, is the airborne receiver which when tuned,
indicates the direction TO the NDB.
 Locator
- Low powered NDB used for approaches in conjunction with an ILS.
Principles:
 NDB
- Operates on frequencies between 200Hz and 500 KHz (LF to MF radio
range).
- Primarily short distance navigation aids of usually < 200Nm.
- Transmitter power is between 100 and 3000W with majority in the 100 to
500W range.
- Greater the transmitter power, the greater the range.
- Details found in ERSA and ERC charts; VTC, TAC and VNC.
- The emitted wave has a Morse code identifier superimposed upon it, of 2
to 3 letters.
- The carrier wave may Also contain voice/ ATIS information.
 ADF
- airborne equipment consists of three main components:
1. Antennae
- loop antenna aligns itself perpendicular to the direction of the received
signal. As it is a loop, two nulls are received - one removed 180 from the
other.
- to resolve the ambiguity the signal from the sense antenna is combined,
to drive the loop (and hence the pointer) in the correct direction.
RMIT Flight Training ADF Operations
Brief 18
RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 2
2. Receiver
- the receiver and associated control panel are used to tune the ADF to the
required NDB.
 OFF = switch ADF off
 ADF = normal position for bearing information
 ANT = only sense antenna is used. No bearing information but enhanced
audio reception
 BFO = beat frequency oscillator, rarely used in Australia
 TEST = deflects needle to right wing. Pressing ADF again points needle
to NDB
3. Cockpit Display
- the needle always points directly TO the station.
4. Fixed-Card ADF
- the needle indicates relative bearing of the station from the aircraft
 Rotatable-Card ADF
- the needle indicates a magnetic bearing TO the station. Any change in
HDG requires re-alignment of the ADF card.
 Radio Magnetic Indicator (RMI)
- is a gyro-stabilised ADF which automatically aligns the card, and indicates
magnetic bearings.
RMIT Flight Training ADF Operations
Brief 18
RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 3
Considerations:
 Limitations
- various limitations effect the readings of the ADF:
a) Coastal Refraction
- when passing from land to sea at an oblique angle, NDB radio waves may
be refracted (bent) due to different conducting and reflecting properties of
land and water. Always refracts towards the land (away from the normal).
b) Co-Channel Interference
- signals received from other NDBs operating on the same frequency, may
give false bearing information. (eg: SHT and BNS) Generally NDBs of
similar frequencies are spaced well apart geographically.
c) Thunderstorm Effect
- thunderstorms generate a lot of radio energy, and the ADF needle may
point towards it; a poor mans weather radar.
d) Terrain Effect
- radio signals have greater range over water than over sandy or
mountainous country where the range is considerably reduced.
Brief 18
RMIT Flight Training ADF Operations
RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 4
e) Mountain Effect
- fluctuating bearings may result from the mixing of radio waves reflected
from the surfaces of mountains.
- higher frequencies minimise this effect.
f) Night Effect
- radio waves take two paths; ground waves (along the Earth’s surface) and
sky waves.
- during the day the sky waves are absorbed by the lower ionosphere. At
night the ionosphere reflects the sky wave back, mixing with the ground
wave, causing errors.
g) Quadrantal Error
- results from the metal construction of the aircraft. Needle of ADF will align
itself to the cardinal points of aircraft. (ie: N, E, S, W) when station in
between these quadrants.
Brief 18
RMIT Flight Training ADF Operations
RMIT Instructor Rating Mass Briefs Issue 1 /2004 Page 5
Air Exercise:
T - Tune to NDB using receiver
I - Identify using Morse code
T - Test by depressing TEST switch
Airmanship:
- Always use NDB within it’s rated coverage
- TIT checks before use
- AM stations not to be used for navigation
- Instrument taxi checks to be completed
Brief 18
RMIT Flight Training ADF Operations

猪也能飞

感谢楼主万分感谢感谢万分

xy8701

谢谢楼主，我正准备去RMIT读书