Communications: radio wave antennas – Antennas – Waterborne
Reexamination Certificate
2001-10-05
2003-02-18
Wong, Don (Department: 2821)
Communications: radio wave antennas
Antennas
Waterborne
C343S725000
Reexamination Certificate
active
06522301
ABSTRACT:
BACKGROUND OF THE INVENTION
a) Filed of the Invention
The present invention generally relates to shipborne facilities for an automatic identification system (AIS). More specifically, the present invention relates to an ADE unit for an AIS, i.e., an outdoor unit capable of being used as an ADE which together with BDE constitutes the shipborne facilities for the AIS.
b) Description of the Related Art
b1) Introduction
As disclosed in the Japanese Patent Laid-Open Publication Nos. H11-326511 and H11-331110, the AIS is a system aimed to contribute to safe and efficient navigation of a ship. To achieve this, the AIS serves to automatically receive/transmit radio messages including static and dynamic information between ships or between a ship and a coast station. In general, the static information contained in a message would not be changed merely by the movement of the ship that originates the message or by the elapse of time. The static information includes items of information useful for identifying the ship that originates the message, such as vessel name, IMO (International Maritime Organization) number, call sign, and so on. The static information also includes other information relating to the character and schedule of the current voyage of the ship originating the message. This information may include the likes of length, width, type, draft, destination, cargo, etc. of the ship. Unlike the static information, the dynamic information including the current position (e.g., longitude and latitude), speed of the ship changes over time and as the ship moves.
The AIS consists of coast facilities installed at coast stations and shipborne facilities mounted on individual ships. To realize ship-to-ship and ship-to-coast station automatic radio messaging, the shipborne facilities must include the following devices.
First, a circuit and an antenna for performing and controlling communications of radio messages are required.
Second, a means for providing a crew of a ship, on which the facility is installed, with static and dynamic information concerning their ship and other ships is necessary. This can be implemented by various display devices, e.g., a CRT and an LCD, and audio output devices including a speaker, a speech synthesizer, and so on.
Third, a means for setting the static information concerning the ship may be necessary. This can be implemented by independent input devices, e.g., a keyboard and a pointing device, or other input devices associated with the display device, such as an operation panel provided on or beside the screen of the display device.
Fourth, a means for obtaining the dynamic information of the ship by way of, for example, measurement may also be needed. Examples of devices used for this purpose include a wireless positioning device, which is best represented by a GPS (global positioning system) receiver, and various sensors, such as a gyrocompass, a log, or the like. Alternatively, another GNSS (global navigation satellite system) may be used in place of, or together with the GPS. The GPS or the GNSS to be used may be supported by terrestrial or satellite supplemental signals. One example is a DGPS (differential GPS) which provides a differential function using a supplemental signal. An SBAS (satellite based augmentation system), which is one type of DGPS designed to have functions of ranging, differential, and integration using satellite signals, may also be used.
b2) Shipborne Facilities
FIGS. 13 and 14
show an example arrangement of conventionally developed shipborne facilities. In the figures, the above deck equipment(ADE) consists of an antenna and its peripheral devices, while the below deck equipment (BDE) includes devices installed in the residential area or workspaces, such as the pilothouse, of the crew. In the figures, a broken line represents the conceptual border line between the ADE and the BDE. A similar line is used in
FIGS. 1 and 12
which will be described later.
In the example shown in
FIG. 13
, the ADE includes a GPS antenna for PPS (pulse-per-second)
10
a
, a VHF antenna
10
b
, and a GPS antenna for positioning
30
a
. The example shown in
FIG. 14
further includes a long range antenna
50
a.
In the example shown in
FIG. 13
, the BDE includes an AIS transponder
10
, an AIS display device
20
, and a GPS receiver for positioning
30
. The example shown in
FIG. 14
further includes a long range aiding device
50
and an associated interface
50
b
, and a gyrocompass
60
and an associated interface
60
a.
As can be seen, various transmission lines are provided between places where the ADE and the BDE are provided, to connect between the ADE and the BDE.
The AIS transponder
10
, which belongs to the BDE, includes a VHF radio circuit
10
c
, a controller
10
d
, and a GPS receiver for PPS
10
e
, as shown in FIG.
15
. It also has a power supply or the like which is not shown. The VHF radio circuit
10
c
carries out the above-mentioned messaging and consists of a TDMA transmitter
10
f
, a TDMA receiver
10
g
, a DSC receiver
10
h
, and other components. The TDMA transmitter
10
f
and the TDMA receiver
10
g
are circuits for receiving and transmitting the message according to the TDMA (time-division multiple-access) method. The TDMA transmitter
10
f
uses the VHF antenna
10
b
to transmit both static and dynamic information concerning the ship on which the AIS transponder
10
is installed to other ships or to coast stations. The TDMA receiver
10
g
uses the VHF antenna
10
b
to receive from other ships static and dynamic information concerning them. In addition, the DSC receiver
10
h
uses the VHF antenna
10
b
to receive DSC (digital selective calling) calls to the ship. It should be noted that, although for the sake of simplicity of drawing, each of the transmission and receiving functions is represented by a single block, additional transmission and receiving systems would be provided as needed in practice according to international law or protocol.
The controller
10
d
controls transmitting/receiving operations of the VHF radio circuit
10
c
as described below. First, when the TDMA receiver
10
g
installed on a first ship receives static and dynamic information concerning, e.g., of another ship, the controller
10
d
correspondingly causes the TDMA transmitter
10
f
to transmit the static and dynamic information concerning the first ship. To succeed in this messaging operation, synchronization in terms of timing of TDMA time slot must be established between the two ships. To do this, the GPS receiver for PPS
10
e
uses the GPS antenna
10
a
to receive a navigation message from a GPS satellite which is in orbit around the earth and, based on received data, derive a reference clock to generate a PPS signal. According to the PPS signal supplied from the GPS receiver for PPS
10
e
, the controller
10
d
controls the operation of the VHF radio circuit
10
c
to synchronize the operation of the VHF radio circuit
10
c
, such as the timing of the TDMA slot, with that of other ships. To secure a precise reference clock, the signal path connecting the GPS receiver for PPS
10
e
and the controller
10
d
should be as short as possible in order to suppress any delays along the signal path. In consideration of this, the receiver for PPS
10
e
is installed inside the AIS transponder
10
.
The controller
10
d
receives the static and dynamic information concerning its own ship and supplies this information to the TDMA transmitter
10
f
to be delivered to other ships. The static information concerning the ship is set in advance in the hardware of the controller
10
d
, or stored therein in a nonvolatile manner. Alternatively, it may also be possible for a crewmember or some other person to set such information at a particular time before departure of the ship, by operating an operation section associated with the AIS display
20
. The operation section may be formed by such devices as buttons beside the display screen, a touch panel on the screen, or an associated keyboard. Pieces of the dynamic information of the shi
Goto Naohisa
Haga Masanori
Takayama Masaki
Yokoyama Naoki
Clinger James
Japan Radio Co. Ltd.
Samuels , Gauthier & Stevens, LLP
Wong Don
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