Optics: measuring and testing – Velocity or velocity/height measuring – With light detector
Reexamination Certificate
2001-07-02
2002-07-23
Tarcza, Thomas H. (Department: 3662)
Optics: measuring and testing
Velocity or velocity/height measuring
With light detector
C342S036000, C356S342000, C382S107000
Reexamination Certificate
active
06424408
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a wake turbulence detecting system detecting by means of laser radar deployed in an airport wake turbulence which appears behind main wings of an aircraft during takeoff or landing and continues to exist along the trail of the aircraft.
2. Description of the Background Art
Wake turbulence is a turbulence winding up vortexes rotating in opposite directions to each other, generated backward of right and left main wings of a flying aircraft. As for the scale of wake turbulence, a diameter of a vortex may extend to a few hundred feet, deteriorating the controllability of the following aircraft entering the trail. When wind is weak, wake turbulence continues to exist in consonance with a trail of an aircraft for a few minutes. Lifetime of the wake turbulence gets longer especially early in the morning when wind is slight and strong radiational cooling occurs. On the other hand, when wind is strong, the wake turbulence may spread, resulting in short lifetime but possible drift downstream from where it started, affecting aircraft flying in other sky areas. In consideration of existence of such wake turbulence, in main airports where many aircraft take off or land aircraft traffic control is carried out. Requests to shorten the time interval between takeoffs or landings are getting stronger to meet the increasing demand for air cargo delivery.
For such requests, laser radar for watching the wake turbulence may be installed in airports and when it is received that there is no wake turbulence the following aircraft can be allowed to take off or land by aircraft traffic control even though a few minutes have not yet passed after the takeoff or landing of preceding aircraft.
FIG. 12
is a figure which shows an airport where a laser radar is deployed. In
FIG. 12
, reference number
30
denotes a runway. Reference number
31
denotes an aircraft. Reference number
32
denotes a wake turbulence generated backward of aircraft
31
. Reference number
33
denotes a laser radar installed in the vicinities of a runway. In addition,
FIG. 13
is a block diagram showing constitution of a conventional wake turbulence detecting system. In
FIG. 13
, reference number
34
denotes a scanning control part which generates scanning control signal for controlling the irradiating direction and the irradiating gun elevation of laser beam. Reference number
35
denotes a beam transmitter-receiver unit which emits a laser beam based on a scanning control signal and detects the reflected laser beam reflected by dust or particles in the atmosphere. Reference number
36
denotes a signal processing device which detects wake turbulence from a reflected laser beam via the beam transmitter-receiver unit. Reference number
37
denotes wake turbulence detecting part which detects wake turbulence from a reflected laser beam and generates wake turbulence information. Reference number
38
denotes a monitor display which displays the wake turbulence information generated by wake turbulence detecting part
37
.
FIG. 14
is a block diagram which shows detailed constitution of beam transmitter-receiver unit
35
. In
FIG. 14
, reference number
39
denotes a beam transmit-receive circuit which excites a laser and generates a reception signal including Doppler information indicating the behavior of dusts or solids in the atmosphere and the intensity of the received reflected laser beam. Reference number
40
denotes beam enlarge-reduce device, which enlarges the width of a laser beam from beam transmit-receive circuit
39
and reduces the width of a reflected laser beam.
Referring now to
FIGS. 12
,
13
and
14
, operation of the wake turbulence detecting system is described. In
FIG. 13
, beam transmitter-receiver unit
35
composing laser radar
33
emits a laser beam toward the direction of runway
30
, namely the flight course traced by aircraft
31
during takeoff. Scanning control part
34
outputs scanning control signal for changing the direction and the gun elevation angle of laser beam to beam transmitter-receiver unit
35
, controlling the beam to scan over the predetermined irradiation area. The transmitted laser beam from beam transmitter-receiver unit
35
is reflected by aerosols such as dusts or solids. The reflected laser beam reflected by dusts or solids returns toward the laser radar and is received by beam transmitter-receiver unit
35
. Beam transmitter-receiver unit
35
generates a reception signal including Doppler information indicating the behavior of dusts or solids in the atmosphere and the reception intensity information of the reflected signal indicating the intensity of the reflected laser beam and outputs them to wake turbulence detecting part
37
of signal processing device
36
.
Wake turbulence detecting part
37
, based on a reception signal transmitted by beam transmitter-receiver unit
35
of laser radar
33
, detects the velocity and the direction of the wind at predetermined constant intervals (e.g. about 30 meters). Furthermore, wake turbulence detecting part
37
, based on scanning control signal transmitted by scanning control part
34
, detects the velocity and the direction of the wind for each direction the beam is pointed. In addition, wake turbulence detecting part
37
, based on the velocity and the direction of the wind along beam transmitting direction and along that of each direction, finds the center position indicating the wake turbulence position, the diameter of a vortex indicating the scale of wake turbulence vortex, and the intensity of wake turbulence, then composing wake turbulence information. Furthermore, wake turbulence detecting part
37
generates display data for indicating the wake turbulence information on monitor display
38
and outputs them to monitor display
38
. Monitor display
38
indicates wake turbulence information such as an outbreak position, a scale and intensity of the wake turbulence based on shown data. In addition, among devices composing a wake turbulence detecting system, laser radar
33
is arranged in the vicinities of runway
30
and signal processing device
36
and monitor
38
are installed inside the control tower.
In the control tower, control person in charge, based on wake turbulence information indicated on monitor display
38
, confirms whether there is a wake turbulence or not. If it is confirmed that wake turbulence does not exist or has already disappeared, the control person in charge promptly directs the following aircraft to take off or land on without waiting for a few minutes defined as minimum time interval for takeoffs or landings of aircraft. Thus, the wake turbulence detecting system enables the control person in charge to watch the wake turbulence from its outbreak to its extinction so that aircraft control is made more efficient.
By the way, there remains a problem that should be solved to execute safer aircraft traffic control by means of a wake turbulence detecting system as mentioned above. For example, though the wake turbulence detecting system shows nonexistence of wake turbulence, if it is unclear whether wake turbulence really does not exist or exists but merely cannot be detected, highly trustworthy aircraft traffic control can not be afforded. Therefore, it desirable that there are no blind spots which disturb the detection of wake turbulence.
As described above, wake turbulence detecting system detects Doppler components from the behavior of dusts and solids floating in the atmosphere and so detects the direction and the velocity of wake turbulence vortex. In order to receive the Doppler components of the intensity (velocity) of the wake turbulence vortex efficiently, It is desirable to deploy the laser radar at a position where laser beam can be oriented in the direction parallel to the vortex direction. In other words, as shown in
FIG. 7
, laser radar
33
can observe wake turbulence
32
well when aircraft
31
is located on the point A. However, it becomes difficult to receive wake turbulence
32
when aircr
Andrea Brian
Mitsubishi Denki & Kabushiki Kaisha
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Tarcza Thomas H.
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