METHOD FOR REPRESENTING RADAR IMAGES OF AN AREA OF ACTION UNDER SURVEILLANCE

PROCEDE POUR REPRESENTER DES IMAGES RADAR D'UNE ZONE D'ACTION SOUS SURVEILLANCE

English Abstract

According to the invention a stationary radar system covering an area of
action to be placed under surveillance, such as an airport, seaport or river
port, generates radar images. Onto each radar image of the area of action
under surveillance which is generated by means of the radar system an optical
image (aerial image) of the same area of action is superimposed by means of a
data processing system. The combination image of the area of action obtained
by this superimposition is transmitted to an observation and surveillance
platform of a tower and from there to receiving monitors of moving targets in
the area of action and represented on same. From the plurality of moving
targets of a combination image the current position of, and possibly also a
part of the path already travelled by, a moving target can be shown (by
afterglow) on its receiving monitor by means of a differential GPS receiving
unit which is assigned to said moving target and with which it can connect.

French Abstract

Selon l'invention, un système radar fixe couvrant une zone d'action placée sous surveillance, telle qu'un aéroport, un port maritime ou un port fluvial, génère des images radar. Une image optique (image aérienne) de ladite zone d'action est superposée, au moyen d'un système de traitement de données, sur chaque image radar de cette zone d'action sous surveillance, qui est générée au moyen du système radar. L'image combinée de la zone d'action, obtenue par cette superposition, est transmise à une plate-forme d'observation et de surveillance d'une tour, puis à des moniteurs de réception de cibles mobiles dans la zone d'action, et représentée sur ceux-ci. A partir de cette pluralité de cibles mobiles d'une image combinée, la position instantanée de, et éventuellement également une partie de la trajectoire déjà parcourue par, une cible mobile peut être mise en surbrillance (par luminescence résiduelle), sur son moniteur de réception, au moyen d'un système de réception GPS en mode différentiel, qui est associé à ladite cible mobile et avec laquelle il peut se raccorder.

Claims

CLAIMS
1. A method for displaying radar images of an action region to be
monitored, such as an airport, a seaport or a river harbor, the images having
been generated by a stationary radar system with the use of a data-processing
system and displaying the action region to be monitored as a representation
from
the viewing position of the stationary radar system, characterized in that the
radar images generated by the radar system, which indicate an instantaneous
status of the action region to be monitored, are superposed with an optical
image
or an image that approximates a cartographic representation (map
representation or aerial image) of the same action region, with the aid of the
data-processing system, and a combination image of this action region, which
has been obtained through the superposing of a radar image and the optical
image of the map representation, is displayed,
2. A method for displaying radar images of an action region to be
monitored, such as an airport, a seaport or a river harbor, including mobile
targets located in the region, the images having been generated by a
stationary
radar system with the use of a data-processing system and displaying the
action
region to be monitored as a representation from the viewing position of the
stationary radar system, characterized in that, with the aid of the data-
processing
system, each radar image of an instantaneous status of the action region to be
8

monitored is superposed with an optical image or a representation (map
representation or aerial image) of the same action region that approximates a
cartographic representation; and that a combination image of this action
region,
which has been obtained through the superposing of a radar image and the
optical image, is displayed on an observation and monitoring platform, and is
transmitted from there to receiving monitors of mobile targets in the action
region,
and displayed on the monitors.
3. The method according to claim 2, characterized in that a differential
GPS (Global Positioning System) receiving device, which is respectively
associated with a specific mobile target and can be activated by the target,
can
determine the target's instantaneous position from the plurality of mobile
targets
displayed on a transmitted combination image, and possibly highlights at least
a
portion of the path that this mobile target has traversed (e.g., with an
afterglow)
on its receiving monitor.
4. The method according to claim 3, characterized in that the
instantaneous position of only one particular mobile target and, possibly, the
path
that has been traversed by this target, is or are highlighted by a prominent
color
marking.
9

5. The method according to one of the foregoing claims, characterized
in that an optical image (aerial image) of 0the action region to be monitored,
the
image being stored in the data-processing system, is layered as the background
beneath the radar image, which has been adapted in its dimensions to the
optical
image.
6. The method according to one of the foregoing claims, characterized
in that a color optical image (aerial image) of the action region to be
monitored,
the image being stored in the data-processing system, is layered as the
background beneath a radar image that has been adapted in its dimensions to
the color optical image.
7. The method according to one of the foregoing claims, characterized
in that all of the back-scattered points of stationary elements or targets of
a
scene (present in the optical image) are gated out of the radar image, and
only
back-scattered points of targets that are not present in the optical image are
displayed in the sublayered optical image.
8. The method according to one of the foregoing claims, characterized
in that all of the back-scattered points of all stationary elements/targets of
a
scene are gated out of the radar image, and only the back-scattered points of
mobile targets are displayed in the sublayered optical image.

9. The method according to one of the foregoing claims, characterized
in that mobile targets that have been detected by the radar system, but are
not
present in the optical image, are displayed in color.
10. The method according to one of the foregoing claims, characterized
in that mobile targets that have been detected by the radar system in
different
sectors (not present in the optical image) are displayed in different colors.
11

Description

CA 02320754 2000-08-17
DESCRIPTION
METHOD FOR DISPLAYING RADAR IMAGES OF AN ACTION REGION TO BE
MONITORED
TECHNICAL FIELD
The invention relates to a method for displaying radar images of an action
region to be monitored, such as an airport, a seaport or a river harbor, or a
similar action region.
to
PRIOR ART
Generally, for monitoring such action regions, a radar system having a
downstream data-processing system is used. If a stationary radar system having
a rotating antenna, for example the tower of an airport or a corresponding
building in a seaport, detects a building, for example, a strung backscatter
signal
is obtained and displayed on monitors of the radar system.
This display essentially corresponds to a sort of perspective, frontal view
of buildings, but includes no notable structures and comprises a plurality of
strong, point-shaped backscatter signals. Edges and other prominent, strongly-
zo reflective points of a detected building appear especially distinct in the
display.
Even a high-resolution radar image does not produce a continuous image
that is comparable to a graphic, visual representation of the building that
can be

CA 02320754 2000-08-17
obtained with, for example, a camera. Moreover, a radar image is always in
black and white.
OBJECT OF THE INVENTION
It is therefore the object of the invention to improve a display obtained with
a radar system in that mobile, that is, moving and/or standing ("parked"),
targets
that are present in a certain action region are far easier to interpret or
identity.
According to the invention, this object is accomplished by methods for
displaying radar images of an action region to be monitored, such as an
airport, a
0 seaport, a river harbor or similar action region, the methods having the
features
of claim 1 or 2. Advantageous modifications are the subject of the claims that
are directly or indirectly dependent on claim 1 or 2.
In a first embodiment of the methods of the invention, with the aid of a
data-processing system, an optical image, or a representation that
approximates
a cartographic representation (referred to hereinafter as map representation
or
aerial image), of the action region to be monitored is superposed over radar
images of an instantaneous status of the action region, the images having been
generated by a radar system, and a combination image obtained through the
superposing of a radar image and the optics! image (aerial image) is then
2o displayed on a monitor.
In connection with realizing the methods of the invention, a radar system
having an antenna that is fixed to a building, preferably the tower of an
airport, a
2

CA 02320754 2000-08-17
seaport or a river harbor, is advantageous; such arrangements are known from
DE 40 07 611 C2 or 40 07 612 C2.
An optical image refers to a continuous image of the action region to be
monitored, the image corresponding to a photographic representation. A
continuous image is an image that is generated to display only the stationary
structures that are necessary for the monitoring and management of air or
maritime traffic, such as buildings and ground facilities or docks, including
the
entire flying field/taxiway or the entire harbor. The image does not, however,
include any mobile targets that change their position, such as aircraft,
ships,
tugboats, boarding vehicles, tankers, passenger buses, luggage carts, etc., or
any temporarily "parked" (immobile, moored) objects. In other words, in the
continuous image or aerial image of an action region to be monitored, such as
an
airport, a seaport or a river harbor, the flying field/taxiway or the actual
harbor
region, appears completely empty.
~ According,to a second preferred embodiment of the methods of the
invention, the combination image of an action region that has been obtained
through the superposing process is displayed on an observation or monitoring
platform of a tower of airports, seaports or river harbors; tram there, it is
transmitted to receiving monitors of mobile targets in the action region, and
o displayed on them. Thus, a connection can be made from the tower to any
mobile target carrying personnel, which are typically already provided with
the
corresponding receiving devices necessary for communication, in order to
3

CA 02320754 2000-08-17
transmit appropriate information or instructions, possibly also with respect
to
mobile targets located in the immediate vicinity.
Furthermore, according to a preferred modification of a second
embodiment of the methods according to the invention, a device that receives
and processes signals of a differential GPS (Global Positioning System), and
is
respectively associated with a specific mobile target and can be activated by
the
target, can determine the target's instantaneous position from the plurality
of
mobile targets displayed on a transmitted. combination image, and possibly
highlights at least a portion of the path that this mobile target has
traversed (e.g.,
1 o with an afterglow) on its receiving monitor, preferably also with color
marking. 1f
mobile targets detected by the radar system are displayed in color, the mobile
target detected by the differential GPS is characterized by a particularly
prominent color marking.
If, as is typically the case for most larger airports, seaports or river
harbors, a device that processes GPS signals is provided, the method of the
invention creates a highly-precise observation and monitoring system for such
airports, seaports or river harbors. The linking of the device that processes
GPS
signals in a tower and the device that processes differential GPS signals in
the
mobile targets, and the linking of receiving and display devices that are also
2o generally provided in mobile targets, such as monitors, a display, etc.,
presents
the personnel of mobile targets, such as pilots, captains, navigators and
general
vehicle operators, not only with precise position information about their own
9

CA 02320754 2000-08-17
vehicle, but also with comprehensive information about vehicles Located in the
immediate and remote surroundings, and their anticipated directions of
movement.
In addition, according to the invention, enlarging specific action region
sectors of interest, such as through zooming, offers personnel on mobile
targets
a far better overview, particularly of the immediate vicinity.
According to a further advantageous modification of the invention, an
optical image/aerial image of the action region to be monitored, which is to
be
sup~rposed over the radar image, is stored in the data-processing system. This
1 o type of stored image can then be layered as the background beneath a radar
image, which is adapted in its dimensions to the stored image.
Upon the availability of a combination image formed from a radar image
and an optical image superposed over the radar image, or an optical image
layered as the background beneath the radar image, points, edges, etc., that
z s originate from stationary, immobile targets such as buildings or other
stationary
installations, and can be clearly distinguished on the radar image by persons
monitoring the action region detected by the radar, can be interpreted more
easily as such, identified precisely with respect to their position, and
therefore
uniquely associated immediately with any fixed, immobile target.
20 In an advantageous modification of the method of the invention, the optical
image is stored in color in the data-processing system, and is therefore ready
for
retrieval. If such a color optical image is layered as the background beneath
a
5

CA 02320754 2000-08-17
radar image, which has been correspondingly adapted in its dimensions, and can
only be displayed in black and white, as stipulated by the system, this
further
improves the interpretation of the obtained combination image and the
association and identification of prominent points, edges, etc., that are
particularly emphasized on the radar image.
According to a further advantageous embodiment of the method according
to the invention, all of the back-scattered points of stationary elements or
targets
of a scene that are likewise present in the optical images can be gated out of
the
radar image, which is preferably superposed over a continuous optical image,
or
a corresponding color map representation as the background, so only the back-
scattered points of targets that are not present in the optical imagelmap
representation are represented in the sublayered optical image/map
representation.
In this way, it is possible not only to detect incorrectly-parked objects, for
example, but also objects such as containers or the like that are parked
temporarily, and are known to be halted for preparations for immediate
transport,
but also to make the monitoring personnel particularly aware of these
objects..
In an especially advantageous manner, a combination image generated in
accordance with the invention can be used not only to correctly interpret
mobile
2 o targets, from smaller vehicles, transport vehicles, luggage carts or the
like, up to
large vehicles, such as aircraft or ships, but to identify the precise
position or the
path that has just been traversed by a mobile target.
6

CA 02320754 2000-08-17
Furthermore, according to another advantageous embodiment of the
invention, al( targets that have been deteoted by the radar system and are not
present in the optical image, including standing ("parked") and mobile
targets,
can be highlighted, for example by the assignment of a color to the targets
that
remain after al) stationary targets of a scene have been gated out, the
targets not
being present in the optics( image. In an advantageous modification of the
invention, a different color can be assigned to the detected mobile targets
from
the one assigned to temporarily-parked, standing targets.
Parked and mobile targets that are not present in different sections of the
optical image, but have been detected by the radar system, can be represented
in different colors.
The method of the invention therefore creates numerous options for
considerably facilitating and improving the interpretation of a radar image,
not
only with respect to mobile targets, but objects or targets that are only
present
temporarily ("parked"), and for identifying such objects or targets faster and
more
reliably.
7