Note: Descriptions are shown in the official language in which they were submitted.
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Ship monitoring system
Technical Field
The disclosure relates to a monitoring system for monitoring ships in shipping
traffic that have AIS ship transmission units and/or AIS ship reception units
for
sending and/or receiving AIS radio signals that contain shipping traffic data
for
the shipping traffic. The disclosure likewise relates to a method for
producing
such a monitoring system and to a method for monitoring the shipping traffic
in
this regard.
Background
Today, monitoring of shipping traffic, which is increasing worldwide, is based
predominantly on radar monitoring systems, radio telephony and the use of AIS
(Automatic Identification System). Since the year 2000, the AIS has been
stipulated as an obligatory standard by the International Maritime
Organization
(IMO) in order to increase the safety of international shipping traffic. This
locally bounded radio system is used in this case for the interchange of
navigation and other shipping data that are meant to allow the ships to obtain
a
comprehensive overview of the adjacent shipping traffic. The primary aim in
this case is to avoid collisions between ships.
The AIS alternately transmits on two channels in the VHF marine radio band,
namely firstly on 168.975 MHz and secondly on 162.025 MHz. In this case, the
individual AIS shipping data items are transmitted in fixed time frames, the
use
of which is automatically coordinated by the relevant subscribers (what is
known as SOTDMA: Self organized time division multiple access). Hence, there
are just 2250 time slots per minute available to the individual subscribers
for
transmitting data.
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On the basis of the VHF frequency band used, the radio range of AIS from ship
to ship corresponds to approximately 40 to 60 km, which corresponds to little
more than normal visibility on the high sea. Coastal stations are able to
cover a
radius of up to 100 km as a result of their relatively high position. On
account
of the limited range and also the SOTDMA transmission protocol used, ships
that are able to see and receive one another form an AIS radio cell within
which the subscribers are able to send and receive without collision.
Hence, the AIS is merely a local radio system that, although it provides
sufficient data for a ship on the high sea, is not suitable for worldwide
collection
of the increasing shipping traffic. For shipping companies, shipping
organizations or environmental ministries, however, real-time collection of
the
AIS shipping traffic data accruing worldwide would be of great interest in
order
to counteract particularly also illegal practices on the high sea.
In the very recent past, attempts have been made to arrange AIS reception
antennas on satellites so as to be able to receive the AIS radio signals
transmitted worldwide that are regularly transmitted by the ships. Although
this
would allow worldwide collection of the shipping traffic data transmitted
using
the AIS, it has considerable difficulties and disadvantages in practice, since
the
AIS has not been developed for satellite reception.
On account of the extremely high altitude of the satellite, a reception range
with
a diameter of approximately 5000 km is produced. Since the AIS, as a local
radio system, automatically organizes itself into individual radio cells that
all
send on the same frequency bands, such a large reception radius results in a
large number of radio cells with identical transmission frequencies being
received. The AIS radio signals from the various AIS radio cells are therefore
superimposed at the receiver, which means that normal data processing is no
longer possible. Instead, the received radio signal needs to be conditioned in
a
complex and computationally intensive manner in order to be able to ascertain
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the individual AIS radio signals from the superimposed AIS radio signals. With
such a large reception range, this is no longer possible on the satellite
alone,
however, which means that the signal processing has to be performed on the
earth's surface in large computer centres.
Furthermore, the AIS radio signals are subjected to severe interference by the
atmosphere when received on the satellite, which impairs the signal quality to
a
considerable extent and hence reduces the number of AIS radio signals that
can be received and evaluated.
Finally, these disadvantages that are conditional upon the satellite system
result in only a fraction of the AIS radio signals transmitted worldwide now
being able to be received and evaluated using AIS reception antennas
arranged on the satellite, which means that this also allows worldwide
coverage
only to a limited extent. Furthermore, the use of satellites and also the
associated complex signal processing are very cost intensive, which means
that for economic reasons alone the use of satellites for receiving AIS radio
signals appears questionable.
Summary
It is therefore an object of selected embodiments to specify a monitoring
system that can be used to receive, and to evaluate in real time, at least
most
AIS radio signals that are transmitted worldwide.
The disclosure generally relates to the monitoring system of the type
described
at the outset in that a plurality of AIS transmission units and/or AIS
reception
units are provided that are arranged on commercial aircraft such that
- at least a portion of the AIS radio signals transmitted by the AIS
ship
transmission units in the shipping traffic can be received by at least
one of the AIS reception units arranged on a commercial aircraft,
and/or
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- the AIS radio signals transmitted by at least one of the AIS
transmission units arranged on a commercial aircraft can be received
by at least a portion of the AIS ship reception units in the shipping
traffic,
when the commercial aircraft are flying in the direction of their destinations
in
the air traffic area.
Accordingly, it is proposed that conventional commercial aircraft are equipped
with appropriate AIS transmission units and/or AIS reception units that are
then
able to receive the AIS radio signals transmitted by the ships, and are also
able
to transmit appropriate AIS radio signals using the transmission units, on
their
flight to their respective destinations. Since conventional commercial
aircraft
usually have a much lower altitude than communication satellites, the possible
reception range is much shorter and is up to 350 km, for example. This
ultimately results in fewer AIS radio cells being able to be received
simultaneously, which reduces the superimposition of the individual AIS radio
signals and therefore reduces the complexity of the signal processing
following
reception of the radio signals. Furthermore, the reception quality is
increased
on account of the lower altitude of the commercial aircraft. Hence, the
reception rate can be increased on account of the shorter reception range. On
the other hand, however, a sufficient plurality of AIS radio cells are still
covered
by a single AIS flying reception unit or AIS flying transmission unit, since
the
commercial aircraft usually have a cruise altitude of several 1000 metres (in
most cases between 8 and 12 km). The number of AIS radio cells that can be
received in this case is sufficient in order to be able to derive an
appropriate
overview.
In this case, the inventors have recognized that a sufficient number of
equipped commercial aircraft allows almost uninterrupted monitoring of the
highly frequented international shipping routes, since firstly most shipping
routes are covered by the flight routes of the commercial aircraft and
secondly
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the high volume of flights means that there is always a certain number of
commercial aircraft in the air that safeguard reception of the AIS radio
signals.
Furthermore, equipping commercial aircraft is much less expensive in
comparison with the design of a satellite system, since it is possible to
resort to
known engineering and it is possible for retrofitting to take place
inexpensively
on the ground.
Advantageously, in addition to the AIS transmission and/or reception units,
AIS
signal processing units are arranged on the respective commercial aircraft,
said
AIS signal processing units being set up to ascertain AIS radio signals from
superimposed AIS radio signals from various AIS ship transmission cells. The
reason is that the lower altitude of the aircraft in comparison with the
satellite
means that fewer SOTDMA cells are also received, which results in less
superimposition of the AIS radio signals from the individual cells. On account
of
this, the signal conditioning or signal processing is much simpler, which
means
that it can actually be performed on board the commercial aircraft. Using an
AIS signal processing unit, it is therefore possible to calculate the
individual
AIS radio signals from the superimposed AIS radio signals from the various
cells, and hence to take them as a basis for further use, during the actual
flight
of the commercial aircraft.
Furthermore, it is quite particularly advantageous if the commercial aircraft
contain an AIS data processing unit that is set up to extract the shipping
traffic
data contained in the AIS radio signals. Hence, the received shipping traffic
data can be ascertained from the AIS radio signals during the actual flight of
the commercial aircraft, as a result of which they can be taken as a basis for
further use. By way of example, the shipping traffic data can now be forwarded
to a ground station, sent as AIS radio signals back to the ships or
transmitted
to the ships using other communication and radio systems.
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Advantageously, the commercial aircraft each contain an AIS data memory for
storing received shipping traffic data so as to be able to collect the
received
shipping traffic data in the event of there being no contact with a ground
station, for example. In this case, the AIS data memory can either store the
AIS
radio signals in raw format or can store the shipping traffic data already
extracted from the AIS radio signals as data records. It is also possible for
shipping traffic data forwarded by other aircraft to be stored in this data
memory for further use.
Advantageously, the AIS reception units are designed such that they generate
a timestamp when receiving shipping traffic data, said timestamp then being
stored together with the shipping traffic data in the AIS data memory. This
means that the time aspect, particularly the age of the relevant data, can
also
be taken into account during later use of the shipping traffic data.
It is quite particularly advantageous if the commercial aircraft have a
communication unit that is set up to transmit received and/or stored shipping
traffic data to a reception station directly or using intermediate stations.
In this
case, such a communication unit may be different from the AIS transmission
and/or reception units so as, by way of example, to forward received shipping
traffic data to other ships, aircraft, satellites or ground stations directly
or using
intermediate stations. This can advantageously be accomplished by resorting
to already existing communication means. Thus, shipping traffic data that have
been received by means of the AIS reception unit on the commercial aircraft
can also be transmitted to the ships by means of these already existing
communication means, so that there is not necessarily a requirement for an
AIS transmission unit on the commercial aircraft.
The communication units that are different from the AIS are naturally also set
up to receive shipping traffic data from a transmission station, for example
in
order to be able to receive shipping traffic data from other aircraft, from
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satellites or from ground stations. These shipping traffic data that a
commercial
aircraft receives via the communication unit can then be transmitted to the
ships in the shipping traffic in the transmission range of the AIS
transmission
unit of the commercial aircraft using the AIS transmission units, for example,
which increases the consciousness of situation and position for the individual
ships within the reception range above their own reception and transmission
horizon.
Alternatively, it is conceivable for the AIS transmission units or AS
reception
units that are already arranged on the commercial aircraft or for additional
AIS
transmitters and receivers to be used as communication means for
communicating with other stations, such as commercial aircrafts or satellites.
By way of example, it is thus possible to use the satellites already equipped
with AIS as intermediate stations in order to interchange information via AIS
between the commercial aircraft and the satellites.
The large number of civil air movements and the fact that most shipping and
aviation routes used are essentially congruent allow real-time AIS signal
monitoring to be performed, as a result of which it is possible to ascertain a
worldwide consciousness of position for the shipping traffic using a ground
station that receives the relevant data, for example. By contrast, the current
AIS satellite systems provide only repeated daily contact, the superimposed
signal problems meaning that the number of shipping traffic data items that
can
actually be received is greatly reduced.
The use of commercial aircraft as transmission and/or reception stations for
sending and/or receiving AIS radio signals means that the commercial aircraft
are used to form an AIS monitoring network or monitoring system having a
worldwide span and allowing real-time, worldwide collection of AIS shipping
traffic data. The intercommunication between the commercial aircraft and the
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interchange of the received shipping traffic data therefore allow a
comprehensive consciousness of position.
Selected embodiments otherwise achieve this with a method for producing a
monitoring system of the above by arrangement of AIS reception units and/or
AIS transmission units on a commercial aircraft.
Furthermore, selected embodiments also are directed to a method for
monitoring ships in shipping traffic that are able to send and/or receive AIS
radio signals containing shipping traffic data by means of AIS ship
transmission
units and/or AIS ship reception units arranged on the ships, wherein
reception of AIS radio signals, containing shipping traffic data, that have
been transmitted by at least a portion of the AIS ship transmission units
in the shipping traffic by means of at least one AIS reception unit
arranged on at least one commercial aircraft, and/or
transmission of AIS radio signals, containing shipping traffic data, that
can be received by at least a portion of the AIS ship reception units in the
shipping traffic by means of at least one AIS transmission unit arranged
on at least one commercial aircraft,
when the at least one commercial aircraft is flying in the direction of its
destination in air traffic.
Advantageous embodiments of the method are described herein.
Brief Description of the Drawings
The disclosure is explained in more detail by way of example with reference to
the appended figures, in which:
Figure 1 - shows a block diagram of
the AIS aircraft unit;
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Figure 2 - shows an illustration of the manner of operation of the monitoring
system;
Figure 3 - shows an illustration of the manner of operation of the monitoring
system for a plurality of radio cells that can be received
simultaneously.
Detailed Description of Selected Embodiments
Figure 1 shows an AIS aircraft unit 1, as it may be used for arrangement on a
commercial aircraft in order to form the monitoring system. The AIS aircraft
unit
1 has an AIS transmission unit 2 and an AIS reception unit 3. The AIS
transmission unit 2 and the AIS reception unit 3 are in this case set up such
that they are able to send and receive AIS radio signals.
Furthermore, the AIS aircraft unit 1 has a signal processing unit 4 that is
connected to the AIS reception unit 3. In this case, the AIS signal processing
unit 4 is set up to process the superimposed AIS radio signals received by the
AIS reception unit 3 so as to calculate the superimposed radio signals from
various AIS radio cells apart. Hence, even when a plurality of radio cells
that
send on one and the same frequency band are received, it is possible for the
superimposed radio signals to be ascertained individually, which substantially
increases the reception rate.
Furthermore, the AIS signal processing unit 4 has a contact connection to an
AIS data processing unit 5 that receives, as an input, the AIS radio signals
conditioned by the AIS signal processing unit 4. The AIS data processing unit
5
of the AIS aircraft unit 1 then extracts the shipping traffic data that have
been
transmitted by the ships in the received AIS radio signals. These received
shipping traffic data can then be transmitted again by means of the AIS
transmission unit 2 to the ships that are situated in the transmission and
reception range of the AIS aircraft unit 1, so as to increase the
consciousness
of position for the ships, since a substantially larger transmission and
reception
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range is set up for the ships. However, the extracted shipping traffic data
can
also be supplied to an AIS data memory 6, advantageously together with a
reception timestamp, in order to keep them for later use.
Finally, the AIS aircraft unit 1 also has a communication unit 7 that is
different
from the AIS radio system, so as to forward the received or stored shipping
traffic data to other aircraft or ground stations directly or using
intermediate
station such as satellites or other flying objects. Furthermore, this
communication unit 7 can also be used to receive shipping traffic data from
other aircraft from other transmission and reception ranges, as a result of
which a common transmission and/or reception range is formed that comprises
the individual transmission and reception ranges of the respective AIS
transmission units and/or AIS reception units.
When the commercial aircraft enters the reception range of a ground station,
for example, it is entirely advantageous, by way of example, if the shipping
traffic data stored in the data memory 6 are then transmitted to the ground
station by means of the communication unit 7, so that over time a complete
overview of the worldwide shipping traffic can be established.
Figure 2 shows the manner of operation of the monitoring system according to
the invention. Commercial aircraft 21 and 22 are each equipped with an AIS
aircraft unit 1, as shown in Figure 1. Each of these commercial aircraft 21
and
22 uses an AIS aircraft unit 1 to form a transmission and/or reception range
21a, 22a within which AIS radio signals can be received from ships 23a, 23b,
24a, 24b and corresponding signals can be transmitted thereto, respectively.
Hence, a plurality of AIS transmission units and/or AIS reception units are
provided that are arranged on a multiplicity of commercial aircraft in order
to
form a common transmission and/or reception range that comprises individual
transmission and/or reception ranges of the respective AIS transmission units
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and/or AIS reception units. The individual transmission and/or reception
ranges
21a and 22a of the respective commercial aircraft 21 and 22 therefore form a
common transmission and/or reception range for sending and receiving AIS
radio signals when the commercial aircraft are flying on their predetermined
trajectories in the air traffic space in the direction of their destinations.
The shipping traffic data ascertained by the commercial aircraft 21 and 22 can
be interchanged among one another via a first communication link 25, as a
result of which the commercial aircraft 22 receives shipping traffic data from
the ships 23a, 23b in the transmission and/or reception range 21a, for
example. The commercial aircraft 22 can then make these shipping traffic data
available to the ships 24a, 24b in the transmission and/or reception range 22a
formed by the commercial aircraft 22 via the AIS radio signals, so that the
ships
24a and 24b receive information about the ships 23a and 23b even though the
latter are in another radio cell and outside the radio range of the AIS.
In this case, the communication link 25 is a direct communication link between
the two commercial aircraft 21 and 22. Alternatively, a communication link 26
that is effected by means of a satellite link is conceivable.
In proximity to a ground station 27, it is furthermore conceivable for the
commercial aircraft 21 to transmit the shipping traffic data received from
everyone, whether directly via the AIS radio signals or indirectly via other
commercial aircraft 22, to this ground station 27 so that a worldwide overview
of the ships and the shipping traffic can be established in said ground
station.
By way of example, this is accomplished via the communication link 28.
Alternatively, it is conceivable in this case for satellite communication 26
to be
used for the communication with the ground station 27 so that appropriate data
can be transmitted to the ground station 27 even outside the range thereof.
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Finally, Figure 3 shows the manner of operation of the monitoring system
according to the invention in the case of a commercial aircraft 31 that can
receive at least two AIS radio cells 32 and 33. The subscribers in the first
radio
cell 32 are two ships 32a and 32b, while the subscribers in the second radio
cell are two ships 33a and 33b. The subscribers in the radio cells 32 and 33
are unable to see one another and can neither receive nor detect their
corresponding transmitted AIS radio signals.
On account of the high altitude of the commercial aircraft 31, the commercial
aircraft 31 is able to receive more than one radio cell, as shown by way of
example in Figure 3 by the reception of the two radio cells 32 and 33. Since
the
subscribers in the respective radio cells send on the same frequency band,
however, corresponding signal superimpositions arise in the case of reception
by the aircraft 31, since the subscribers in the respective radio cell 32 and
33
are sending on the same frequency bands. Therefore, the radio signal received
by the commercial aircraft 31 must first of all be conditioned by signal
processing in order to be able to individually ascertain the individual AIS
radio
signals transmitted by the individual subscribers in the radio cells 32 and
33.
Once this has happened, the shipping traffic data from the subscribers 32a,
32b, 33a and 33b can be extracted from the AIS radio signals and are therefore
available for further use. By way of example, it is thus possible for the
commercial aircraft 31 to now spontaneously transmit AIS radio signals to the
transmission and/or reception range 34, so that the subscribers in the first
radio cell 32 are able to receive shipping traffic data for the subscribers in
the
second radio cell 33, even though they would not be able to receive them under
normal circumstances. The same also applies to the subscribers in the second
radio cell 33, which receive shipping traffic data from the subscribers in the
radio cell 32 from the commercial aircraft 31.
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It is naturally also conceivable for the shipping traffic data that are
intended to
be transmitted to the ships also to be transmitted via alternative
communication
links, as a result of which it is possible to dispense with the AIS flying
transmission unit on the satellite, for example.
This allows the consciousness of situation and position to be increased for
every single ship, since there are now much more data and information
available than is possible under normal circumstances, since it is normally
assumed that data interchange among one another takes place only in visual
range.
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