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时间:2011-02-04 12:13来源:蓝天飞行翻译 作者:admin
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loc is the localizer noise, w5 is a white noise signal, generated internally within
the block LOCnoise1 or LOCnoise2, and Hloc is the transfer function of the localizer
noise filter.
• Transfer function of the localizer noise filter according to AGARD R-632, used for LOCnoise1:
Hloc(s) = sloc
r
2Lloc
V
1
1 + Lloc
V s
Note: the value of the airspeed V used by LOCnoise1 is assumed to remain constant
during the simulations. This is not entirely accurate, but if this value is set equal to the
(final) approach speed of the aircraft, the results are quite usable, keeping in mind that
this equation only provides an approximation of actual localizer noise anyhow. Lloc is
the scale-length of the localizer noise; sloc is the standard-deviation.
• Transfer function of the localizer noise filter according to NASA CR-2022, used for
LOCnoise2:
Hloc(s) = 5 (1.5 + s)
(0.35 + s)(10 + s)
Inputs
None.
Outputs
Di
loc localizer noise, D_iloc*
Parameters
For the AGARD R-632 version (LOCnoise1), the user must specify the scale length Lloc,
the standard deviation sloc, and the approach speed of the aircraft. The parameters can
be set in the mask dialog, which is opened after double-clicking LOCnoise1. The NASA
CR-2022 version (GSnoise2) doesn’t require any parameters to be entered.
Connections
in: no connections.
out: Di
loc is meant to be added to the original localizer current iloc. If steady-state errors
are also taken into account, this summation must take place after sending the localizer
current through the block LOCerr first. The resulting signal can e.g. be used as
an input signal for an automatic approach controller.
Type browse locnoise at the command-line for on-line help.
10.1. The radio-navigation blocklibrary 189
VOR Main FDC library / ILS/VOR radio-nav / VOR signals / VOR
Radio-navigation library / VOR signals / VOR
Type
Masked subsystem block.
Description
The block VOR computes the nominal VOR signals that will be received on board the
aircraft if it flies at a certain position relatively to the VOR ground station. In addition,
it computes the ground-distance to the VOR antenna, warning flags which alert the user
if the aircraft flies outside the VOR range, and a flag that tells us whether the airplane is
heading to or from the VOR station.
Equations
For a detailed discussion of the equations from the block VOR, refer to section 5.2.1.
• VOR radial that corresponds to the current position of the aircraft, [rad]:
QDR = arctan

ye − yVOR
xe − xVOR

• Deviation from the desired VOR bearing, [rad]:
GVOR = CD − QDR
• Ground-distance from the aircraft to the VOR station, [m]:
RVOR =
q
(xe − xVOR)2 + (ye − yVOR)2
• A Cone of Silence flag (‘C.O.S.-flag’) is set equal to 1 if the airplane flies inside the Cone
of Silence region, i.e. if:
arctan

H − HVOR
RVOR

> 90 − (40 to 60)
In practice, the smallest cone-size has been used; this corresponds to an opening angle
of 2  40. See figure 5.12 in chapter 5 for more details.
• A Range flag is set to 1 if the aircraft flies outside the area where the VOR signals can
reliably be received, i.e. if:
RVOR > Range
where:
Range = 1000

−2.3570 · 10−6(H − HVOR)2 + 5.7087 · 10−2(H − HVOR) + 80.8612

• A To/From flag is set to 1 if the aircraft is heading towards the VOR station, i.e. if:
|y − QDR| > 90
Inputs
uvor = [ xe ye H ]T aircraft coordinates and altitude, uvor
y heading of the aircraft, psi
Outputs
yvor1 = GVOR nominal VOR bearing, excluding system offset, yvor1
yvor2 = RVOR ground distance from aircraft to VOR station, yvor2
yvor3 = [ C.O.S.-flag Range-flag ]T flags specifying validity of VOR signals, yvor3
yvor4 = ToFrom To/From flag, yvor4
Parameters
The user must specify the coordinates of the VOR station measured in the horizontal
plane, relative to the initial position of the aircraft. Also, the elevation of the VOR station
190 Chapter 10. Radio-navigation block reference
and the Course Datum (the reference VOR bearing which the aircraft is supposed to track)
must be entered. This can be done after double-clicking the block VOR.
Connections
in: uvor is a subset of the state vector x from the nonlinear aircraft model. Also, the
heading y corresponds to one of the state variables from x.
out: in the example system VOR example, the outputsignal yvor1 is sent through the
 
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