Note: Descriptions are shown in the official language in which they were submitted.
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MOBILE SATELLITE TEPMINAL EQUIPMENT
BACKGROUND OF THE INVENTION
The present invention relates to a mobile satellite
communication.terminal equipment.and, particularly, to a
mobile satellite communication terminal equipment which
can also be used as a ground mobile terminal performing
communication through only ground facilities.
It is well known that, as a communication system
to be used in a mobile telephone or portable telephone,
there are two kinds of system, a ground mobile communication
system (cehlular system) which utilizes only ground
facilities and a mobile satellj_te communication system
which utilizes a satellite.
In the ground mobile communication system such as
mobile telephone system which has been popularized recently,
a mobile telephone which is the: mobile communication
terminal communicates, through radio wave, together
with a nearest radio base stat9~on which is connected
to a fixed telephone network through an upper exchange
station, so that the mobile te7Lephone can communicate
with a subscriber of the network.
On the other hand, although the mobile sate111te
communication system is inoperable in an area such as
underground area, interior of a building or area under
an overhead construction which is out of line-of-sight
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of a satellite, it is operable in any out-of-way area
such as solitary island or mountain area in which the
ground communication system can not provide services
economically, so long as the out-of-way area is on a
S direct line-of-sight of the satellite. Therefore, the
mobile satellite communication system having a wide
service area is expected as a complementary system for
the ground mobile communication system.
Particularly, in a mobile satellite communication
system utilizing a Low Earth Orbit (LEO} satellite in
Which a distance of a mobile ground terminal measured
from the LEO satellite is short: and a beam irradiation
range is narrow compared with a stationary satellite, a
communication is possible with lower receiving sensitivity
and smaller transmission power of the terminal. Therefore,
it is possible to reduce a size: and weight of the mobile
terminal and power consumption thereof. Thus, the mobile
terminal of the satellite system can be realized with the
size and cost compatible with those of the mobile terminal
of the ground communication system.
However, the mobile grouncL communication system and
the mobile satellite communication system had been
developed separately from each other and an antenna,
a high frequency portion and a radio control portion
. of the mobile terminal of each system are assembled as
a discrete integral unit.
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Thereforer when a user moves from an area in which
either one of the mobile ground communication and the
mobile satellite communication is possible to another
area in which only the other communication is possible,
he must bring the mobile terminals of the both systems
with him. This is troublesome for the user.
In order to solve this problem, Japanese Patent
Application Laid-open No. H1-248715 (1989) proposes a
single mobile terminal which can be connected to either
of the ground system and the satellite system. That is,
as shown in Fig. 1, the proposed mobile terminal comprises
a satellite system antenna 101, a ground system antenna 102,
a satellite system high frequency portion 103 connected
to the satellite system antenna 101, a ground system high
frequency portion 104 connected to the ground system
antenna 102, a receiving IF switch circuit 105 for
selecting an output intermediate frequency signal of
either one of the high frequency portions 103 and 104,
a transmitting IF switch circuit 106 for selectively
outputting a transmitting intermediate frequency signal
to~either one of the high frequency portions 103 and 104,
a demodulator 107 for demodulating the intermediate
frequency signal from the receiving IF switch circuit,
a~modulator 108 for modulating a transmitting signal, a
baseband processor 109 for processing signals according
to a protocol of a selected one of the satellite system
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and the ground system, a telephone set 110 and a portable
computer 111.
According this mobile ternu.nal, the baseband
processor, the telephone set and the portable computer
which are related to a signal processing subseguent to
the IF signal are used commonly for the satellite system
and the ground system.
However, since the antennas and the high frequency
portions of the respective systems are incorporated, both
the transmitting and receiving systems must be transported
even when only one of the ground and satellite systems is
used. Further, since both of the receiving IF switch
circuit and the transmitting IF' switch circuit are
necessary, the terminal can not. be enough compact and
enoLgh light-weight, causing th.e portability thereof
to be low and the reduction of cost to be impossible.
Further, the mobile satellite communication system
can not be used in an area such. as underground area,
interior of a building or area under an overhead
construction which is out of line-of-sight of a satellite
and, since a communication, from an office in a country
or area in which the ground communication system can not
work effectively is impossible unless the satellite is
on a line-of-sight of the terminal, the terminal must be
moved close to a window of the office.
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SUMMARY OF THE INVENTION
The. present invention was made in view of the problems
inherent to the conventional mobile satellite terminal
and has a first object to provide a compacg and light
weight mobile satellite terminal which can be used as
a ground mobile communication germinal as well as a
satellite mobile communication terminal.
A second object of the preasent invention is to
provide a mobile satellite communication relay device
which makes a mobile ground conununication and a mobile
satellite communication possib7.e when the mobile satellite
terminal equipment is in out o!: line-of-sight of a
satellite.
In order to achieve the fj.rst object of the present
invention, a mobile satellite germinal according to the
present invention comprises a Foatellite system antenna/
high frequency unit, a ground system antenna/high
frequency unit and a radio control unit which is
selectively connected to one of the satellite system
antenna/high frequency unit andl the ground system antenna/
high frequency unit through a radio control interface.
The satellite system anter.~na/high frequency unit
comprises a satellite system antenna of a mobile satellite
communication system and a satellite system high frequency
portion connected to the satellite system antenna. The
satellite system high frequency portion is adapted to
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convert a receiving signal into an intermediate frequency
signal and output it to a first interface and to convert
the intermediate frequency signal input through the first
interface into a satellite system high frequency signal.
The first interf ace is provided externally of a casing
of the satellite system antenna,/high frequency unit.
The ground system antenna/laigh frequency unit
comprises a ground system antenna of a mobile ground
communication system and a growad system high frequency
portion connected to the ground system antenna. The
ground system high frequency portion is adapted to convert
a receiving signal into an intermediate frequency signal
and output it to a second inter:l:ace and to convert the
intermediate frequency signal input through the second
interface into a ground system high frequency signal.
The second interface is provided externally of a casing
of the ground system antenna/high frequency unit.
Further, the radio control unit includes a circuit
portion provided internally of .3 casing thereof for
demodulating a receiving input :intermediate frequency
signal input from one of the ground and satellite antenna/
high frequency units through a :radio control interface
according to a demodulation system assigned to the one
unit and outputs a transmitting signal. to the radio
control interface after modulating it according to a
modulation system assigned to t:he one unit and then
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converting it into an intermediate frequency. The radio
control interface is provided externally of the casing thereof.
The radio control unit further comprises at Least a key board
and a telephone set externally of the casing thereof. One of
the first and second interfaces is connected to the radio
control interface when corresponding one of the satellite and
ground antenna/high frequency units is used.
Further, in the present invention, the satellite
system antenna/high frequency unit. is adapted to generate a
control signal for switching the modulation and demodulation
systems of the circuit portion of the radio control unit to
those suitable for the mobile satellite communication system
when its interface is connected to~ the radio control interface
thereof and the ground system ante:nna/high frequency unit is
adapted to generate a control signal for switching the modula-
tion and demodulation systems of the circuit portion of the
radio control unit to those suitable for the mobile ground
communication system when its interface is connected to the
radio control interface of the radio control unit.
In accordance with the present invention, there is
provided a mobile satellite equipment comprising a relay device
for relaying between a mobile satellite communication system
and a mobile ground communication system, said relay device
comprising: a first antenna/high frequency unit including a
first mobile communication system antenna and a high frequency
circuit connected to said first mobile communication system
antenna converting a receiving signal into an intermediate
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frequency signal, outputting it to a first interface and
converting an intermediate frequency signal input from said
first interface into a high frequency signal, said first inter-
face being provided externally of a casing of said first
antenna/high frequency unit; a second antenna/high frequency
unit including a second mobile communication system antenna
and a high frequency circuit connected to said second mobile
communication system antenna and adapted to convert a receiving
signal into an intermediate frequency signal and outputting it
to a second interface and to convert an intermediate frequency
signal input from said second interface into a high frequency
signal, said second interface being provided externally of said
casing; and a repeater including a. first radio control interface
and a second radio control interface for performing a bi-
directional signal transmission beaween said first radio control
interface connected to said first interface of said first
antenna/high frequency unit and a second radio control interface
connected to said second interface: of said second antenna/high
frequency unit.
As mentioned above, in the present invention, in
either the ground system or the satellite system, the radio
control unit demodulates a receiving intermediate frequency
signal having frequency which is common for
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the ground system and the sate7.lite system and converts
the transmitting signal into an intermediate frequency.
Therefore, it is possible to use the same radio control
unit regardless of whether the mobile communication
system is the ground system or the satellite system and
it is possible to communicate together with the other
side through a desired mobile communication system by
selectively connecting one of t:he first and second
interfaces to the radio control. interface of the radio
control unit according to the mobile communication
system selected.
Further, in the present invention, the satellite
system anterna/high freguency unit or the ground system
antenna/high frequency unit generates the control signal
when it is connected to the radio control interface of
the radio control unit to switch the modulation and
demodulation systems of the circuit portion of the
radio control unit to those suitable for the mobile
co~nunication system selected. Therefore, it is possible
to automatically switch the modulation and demodulation
systems of the circuit portion of the radio control unit
to those suitable for the selected one of the ground
antenna/high frequency unit and the satellite antenna/
high frequency unit when it is connected to the radio
control unit.
In order to achieve the second object of the present
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invention, a relay device for the mobile satellite
communication according to the: present invention
comprises a first antenna/high frequency unit including
an antenna of a first mobile conmunication system and
a high frequency portion connected to the antenna for
converting a receiving signal into an intermediate
frequency signal and converting an intermediate frequency
signal input through a first interface into a high
frequency signal, the first interface being provided
externally of a casing of the first antenna/high
frequency unit and a second_antenna/high frequency unit
including an antenna of a second mobile communication
system and a high frequency portion connected to the
antenna for converting a receiving signal into an
intermediate frequency signal and converting an
intermediate frequency signal :Lnput through a second
interface into a high frequency signal) the second
interface being provided externally of a casing of the
second antenna/high frequency unit. The first interface
is connected to a first radio control interface and the
second interface is connected t:o a second control
interface and a bi-directional signal transmission is
pe~fvrmed between the first and; second radio control
interfaces. Thus, a function of a relay device is
realized.
Further, the first antenna./high frequency unit
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includes a satellite-system antenna for transmitting/
receiving radio signal with re:apect to a satellite and
a high frequency circuit for converting a receiving
signal into an intermediate frequency signal ,and supplying
it to the first radio control j.nterface and for converting
a transmitting signal into a hj.gli frequency signal for
the mobile satellite communication system) The second
antenna/high frequency unit includes a ground system
antenna for transmitting/receiving radio signal with
respect to the mobile satellite: communication terminal
and a high frequency circuit for converting a receiving
signal into an intermediate frequency signal and supplying
it to the second radio control interface and for converting
a transmitting signal into a high frequency signal for
the mobile ground communication. system)
As mentioned above, in the mobile satellite
communication terminal of the present invention, the
first interface of the first antenna/high frequency unit
and the second interface of the second antenna/high
frequency unit are connected to the first and second
radio control interfaces of the relay device, respectively,
so that the bi-directional signal transmission is
performed between the first and second radio control
interfaces. Therefore. a commu:nicat.ion is possible
between a mobile communication ;system capable of
transmitting/receiving a signal by means of the first
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antenna/high frequency unit and another mobile communication
system capable of transmitting,~receiving a signal by means
of the second antenna/high fret;uency unit.
Particularly, when the first antenna/high frequency
unit is the satellite system antenna/high frequency unit
and the second antenna/high frequency unit is, the ground
system antenna/high frequency unit, for radio communication
With respect to the mohile satellite communication terminal,
it is possible to realize a mobile communication with
respect to the mobile satellitE~ communication terminal
through the satellite.
BRIEF DESCRIPTION OF THE DRAWIrIGS
Fig. 1 is a block circuit diagram showing a
conventional mobile communication terminal;
Fig. 2 is a perspective view of a mobile communication
terminal according to the present invention;
Fig. 3 is a block circuit diagram of an embodiment
of the mobile communication terminal of the present
invention;
Fig. 4 is a block circuit diagram showing the present
mobile communication terminal in more detail;
Fig. 5 shows a data format of a control signal used
in the present mobile communication terminal;
Fig. 6 is a block circuit diagram of another embodiment
of the mobile communication terminal according to the
present invention;
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Fig. 7 shows another embodiment of the radio control
unit of the mobile communication terminal of the present
invention;
Fig. 8 is a perspective view of a relay device
according to the present invention;
Fig. 9 is a block circuit diagram of the relay
device of the present invention; and
Fig. 10 is a block circuit: diagram of a system
converter portion of the relay device of the present
invention.
DESCRIPTION OF THE PREFERRED E1'4BODIMENTS OF THE INVENTION
An embodiment of a mobile satellite communication
terminal according to the present invention will be
described with reference to Fic~. 2 which shows a
construction of the mobile satellite communication
terminal in perspective view. As shown in Fig. 2, the
mobile satellite terminal 7 of the present invention is
constructed with a satellite system antenna/high frequency
unit 11, a ground system antenna/high frequency unit 12
and a radio control unit 13.
The satellite system antenna/high frequency unit 11
is constructed with a satellite: System antenna for a
mobile satellite communication system, a satellite system
high frequency portion connected to the satellite system
antenna and an interface lla externally provided on the
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satellite system antenna/high frequency unit 11 as a
connector including an interface circuit. The ground
system antenna/high frequency unit. 12 is constructed with
a ground system antenna for a mob:Cle ground communication
system, a ground system high frequency portion connected
to the ground system antenna and'an interface 12a
externally provided on the ground system antenna/high
frequency unit 12 as a connector.
The radio control unit 13 includes a circuit portion
to be described later) which democ3ulates an intermediate
frequency signal (IF signal) of a receiv=ng signal
according to a demodulation system assigned to selected
one of the satellite communication system and the ground
comraunicatior. system and modulates a transmitting audio
or data signal according to a modulation system ass'_gned
to the selected communication sys~em and converts it
into an IF signal. Further, the .radio coat=of unit 13
is provided, in an upper portion ~of a casing thereof,
with an interface 14 to which either of the ground system
antenna/high 'requency unit 12 or the satellite system
anten.-~a/high frequency unit 11 is selectively connected.
On a front panel of tze casing of the radio control unit
13, a receiver 15a, a transmitter 15b, a display 16 and
a~key board (ten key) 17 aye provided.
. Fig. 3 is a schematic block diagram of the
embodiment of the present invention shown fn Fig. 2.
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In Fig. 3, the interface lla of the satellite system
antenna/high frequency unit 11 is provided on, for example,
a lower portion of the casing thereof as in the case of
the interface 12a of the ground system antenna/high
frequency unit 12. Each of the interfaces lla and 12a
has suitable site and configuration for connection to
the interface 14 of the radio control unit 13.
Further, in order to tranamit other information than
audio signal, the radio contro:L unit 13 is equipped with a
facsimile interface 19 connectable to a facsimile device 21
and a power supply interface 20 connectable to an external
A.C. power source such that it can operate with the
external power source. The power source adapter 22
functions to convert an A.C. power from the external
power source into a D.C. power" When the radio control
unit 13 is to be operated with a D.C. power directly, the
latter can be supplied from, for example, a car battery.
Fig. 4 is a detailed blocF; circuit diagram of an
embodiment of the radio control unit 13 and an antenna/
high frequency unit 25 which may be either the satellite
system antenna/high frequency unit 11 or the ground
system antenna/high frequency unit 12 and connected to
the radio control unit 13. In Fig. 4, same components
as those shown in Figs. 2 and ~4 are depicted by the same
reference numerals, respective7.y.
As shown in Fig. 4, the radio control unit 13 is
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constructed with an interface 19 which can connect either
the ground system antenna/high frequency unit 12 or the
satellite system antenna/high frequency unit 11, a
telephone set 15 including the. receiver 15a and the
transmitter 15b, a display 16, a key board 17, a receiving
IF circuit 31, a demodulator 32, a baseband processor 33.
a modulator 34 and a transmitting IF circuit 35. The
facsimile interface 19 and the power source interface 20
are omitted for simplicity of illustration.
The antenna/high frequency unit 25 is constructed with
a satellite or ground system antenna 26, a high frequency
circuit 27 and an interface 28 which is the interface lla
when the antenna/high frequency unit 25 is the satellite
system antenna/high frequency unit 11 or the interface 12a
when the antenna/high frequency unit 25 is the ground
system antenna/high frequency unit 12. The satellite
system antenna/high frequency unit 11 differs from the
ground system antenna/high frequency unit 12 in that a
higher power amplifier in the i_ransmitting portion of
the satellite system antenna/high frequency unit 11 than
a power amplifier of the transrnitting portion of the
ground system antenna/high free;uency unit 12 is required
and a lower noise amplifier of the receiving portion of
the satellite system antenna/hj.gh freguency unit 11 than
a amplifier of the receiving portion of the ground system
antenna/high frequency unit 12 is required. The. operating
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frequency band of the sate111te system and that of the
ground system are generally in L band and, since the
frequency difference therebatween is small, a common
use of the single radio control unit 13 is possible.
Therefore, in order to realize a combined use of the
satellite system and the ground system economically,
the satellite system antenna/h.igh frequency unit and
the ground system antenna/high frequency unit are
selectively used.
Now, an operation of this embodiaent will be
described with reference to Figs. 2 to 4. hfien the
mobile communication system wh:Lch is to be selected by
a user is the satellite system,. the interface 11a of
the satellite system antenna/h:Lgh frequency unit 11 is
connected to the interface 14 of the radio control unit
13 and, when the mobile communication system which is
to be selected by the user is t:he ground system, the
interface 12a of the ground sy~~tem antenna/high frequency
unit 12 is connected to the interface 14.
By connecting the interface 28 (lla or 12a) of the
antenna/high frequency unit 25 (the satellite system
antenna/high frequency unit 11 or the ground system
antenna/high frequency unit 12) to the interface 14 of
the radio control unit 13, the satellite system antenna/
high frequency unit 11 or the ground system antenna/h.igh
frequency unit 12 is fixedly connected to the radio control
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unit 13 and, as shown in Fig. ~4, a demodulation control
signal a and a modulation cont:col signal b of the satellite
or ground system from the high frequency circuit 27 are
input to the radio control unii~ 13 through the interfaces
28 and 14, respectively. That is, the demodulation control
signal and the modulation control signal are contained in
a control information data portion 32 of a control signal
which takes in the form of a serial data composed of a
preamble data portion 31 and the control information data
portion 32 such as shown in Fi<~. 5 and is supplied from
the high frequency circuit 27 i~o the radio control unit 13.
The demodulation control signal a is supplied to the
demodulator 32 and the baseband processor 33 to switch
the demodulator 21 such that the latter performs a
demodulation according to a demodulation system assigned
to the antenna/high frequency unit 25 connected to the
radio control unit 13 and to switch the baseband processor
33 such that the latter perforrns the receiving signal
processing according to a predetermined system assigned
to the natsann/htgh frequency unit 25. The demodulator
32 can select one of various demodulation systems
according to the demodulation control signal a such
that it can demodulate an input: signal according to a
modulation system used in the satellite communication
or the ground system.cellular, etc. For example, one
of MSK, BPSK, QPSK and 8~ -PSK demodulation systems, etc.,
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can be controlled by using a control bit of the
demodulation control signal a.
At the same time, the modulation control signal b is
supplied to the baseband proce:~sor 33 and the modulator
34 to switch the baseband procea sor 33 such that the
latter performs a transmitting grocessing in the baseband
processor 33 according to a predetermined system assigned
to the antenna/high frequency unit 25 connected to the
radio control unit 13 and to switch the modulator 34 such
that the latter performs a predetermined modulation
assigned to the antenna/high frequency unit 25.
Thus, by merely connecting' the interface 28 (lla or
12a) of the antenna/high frequency unit 25 (satellite
system antenna/high frequency unit 11 or the ground system
antenna/high frequency unit 12) to the interface 14 of the
radio control unit 13,~the antenna/high frequency unit 25
to which the demodulator 32, th.e baseband processor 33
and the modulator 39 of the radio control unit 13 are
con.~ected is automatically switched to perform the
modulation and demodulation according to the satellite
system when the unit 25 is the satellite system antenna/
high frequency unit 11 and the ground system when the
unit 25 is the ground system antenna/high frequency unit
12. In addition to the difference of modulation and
demodulation systems between the satellite system and
the ground system, when, for example, a frequency control
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system and/or an error correctj_on system of the satellite
system are different from those of the ground system, it
is of course possible to switch between them according
to the control information data 32.
Therefore, the receiving 7:F signal obtained by
converting the receiving signal, received by the antenna 26
of the antenna/high frequency unit 25 into a predetermined
intermediate frequency by the high frequency circuit 27
is input through the interface:; 28'and 14 to the receiving
IF circuit 31 and then to the demodulator 32 in which ft
is demodulated normally. The high frequency circuit 27
has a function of converting a signal in a microwave band
or sub-microwave band which is used for the mobile
communication of the satellite or ground system into
an intermediate frequency.
In order to simplify the construction of the radio
control unit 13, it is preferable to select a frequency
relation of the high frequency circuit 27 such that this
. intermediate frequency becomes common for the satellite
system antenna/high frequency unit 11 and the ground
antenna/high frequency unit 12..
Further, in order to tran:~mit the intermediate
frequency in the interface 14 between the antenna/high
frequency unit 25 and the radio control unit 13, to
prevent problems of a signal leak due to high frequency
signal transmission. and a degr~3dation of transmission
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characteristics from occurring and to simplify a
demounting of the interface 14, it is preferable that
an intermediate frequency band is as low as possible.
In the. present invention, in order to construct
the interface 14 Without using a high frequency coaxial
connector, the intermediate frequencies of the the
satellite system antenna/high frequency unit 11 and the
ground antenna/high frequency unit 12 are commonly in
about 4 I~lHz band. In order to~ obtain this intermediate
frequency, local oscillation frequencies of the high
frequency circuits of the units 11 and 12 are selected
as suitable values.
A demodulation signal c of the baseband derived
by the demodulator 32 is supplied to the baseband
processor 33 together with a f.emodulation clock d,
processed thereby according to a related protocol
and converted into an audio signal or a video data.
. The receiving audio signal derived from the baseband
processor 33 is supplied to the telephone set 15 and
the video signal is supplied t:o the display 16 and
displayed thereby.
On the other hand, during a signal transmission,
a transmission data input fronn the key board I7 or
an audio signal input from the telephone set 15 1s
processed by the baseband processor 33 according to a
protocol suitable to the antenna/high frequency unit 25
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and a resultant transmission signal a is supplied to the
modulator 34 together with a transmission clock f and
modulated according to the switched modulation system.
A modulated wave output from the modulator 34 is
. converted by the transmission IF circuit 35 into the IF
signal having the predetermined intermediate frequency
and supplied to the high frequency circuit 2? through
the interfaces 14 and 28. Then., it is converted by the
high frequency circuit 27 into a high frequency signal
in the transmission frequency band and transmitted from
the antenna 26.
As mentioned above, according to this embodiment,
the mobile satellite communication equipment is realized
by connecting the Interface lla of the satellite system
antenna/high freguency unit 11 to the interface 14 of the
radio control unit 13 and the mobile ground communication
equipment is realized by connecting the interface 12a of
the ground system antenna/high frequency unit 12 to the
interface 14 of the radio control unit 13.
Therefore, by selecting on.e of the satellite system
antenna/high frequency unit 11 and the ground system
antenna/high frequency unit 12 to be connected to the
radio control unit 13 depending upon whether the mobile
communication system to be used. is the satellite system
or the ground system, it is possible to always perform
a mobile communication.
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Further, since, in this embodiment, it is possible
to commonly use the radio control unit 13 for the mobile
communication of the satellite and ground systems while
changing only the antenna/high frequency unit, this
embodiment is advantageous in size, weight, portability
and cost compaxed with the mobile communication equipment
disclosed in Japanese Patent Application Laid-open No.
H1-248715.
Another embodiment of the ;present invention will
now be described. Fig. 5 shows a construction of the
embodiment schematically. In Fig. 6, same constructive
components as (hose shown in Fig. 2 are depicted by the
same reference numerals, respectively, without detailed
description thereof. This embo~di.ment is constructed
with a satellite system antenna/high frequency unit 41,
a ground system antenna/high frequency unit 42 and a
radio control unit 43.
The satellite system anten:na/high frequency unit
41 is constructed with a satellite system antenna for
a mobile satellite communication system, a satellite
system high frequency portion connected to the satellite
system antenna and an interface 41a provided on a front
panel of a casing of the unit.
The ground system antenna/:high frequency unit 42
is constructed with a ground system antenna for a mobile
ground communication system, a ground system high frequency
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portion connected to the ground the ground system antenna
and an intezface 42a provided en a front panel of the
unit 42. Each of the antenna/high frequency units 41
and 42 has the same construction as that of~the antenna/
high frequency unit 25 shown in Fig. 4.
On the other hand, the radio control unit f3 has the
same circuit construction as that of the radio control
unit 13 shown in Figs. 2 to 4. Further, the receiver 15a
is provided on a front panel ot: a casing thereof and an
interface is provided on a rear surface of the casing.
That is, this embodiment differs from the embodiment
shown in Figs. 2 to 4 in only that the interface 41a of
the satellite system antenna/hj.gh frequency unit 41 or
the interface 41a of the ground system antenna/high
frequency unit 42 is connected to the interface provided
on the rear surface of the casing of the radio control
unit 43. Therefore, this embodiment can provide the
same effect as that obtained in the preceding embodiment.
Another embodiment of the radio control unit will
be described. A radio control unit 51 shown in Fig. 7
includes a disglay portion 62 which functions as the
display 16 and the key board l~' provided on the front
panel of the casing of the embodiment shown Fig. 6.
That is, the display portion 62 is of a touch-panel
type so that the pressure sensjaive key input as well
as the display is possible.
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The present invention is not limited to the described
constructions and many modifications thereof are possible
within the scope of the present. invention. Foz example,
in order to.accommodate various transmission/receiving
S frequencies, the satellite system antenna/high freguency
unit lI or 41 may be constructe~d~such that it. can be used
in h band (1.5 GFIz to 1.6 GHz) for the INMARSAT satellite
or in S band (2.5 GHz to 2.6 GFtz?.
Since, for the ground system, the usual telephone
frequency band of 800 MHz and various frequency bands
used in MCA radio system, private radio system and room
radio system are used; the ante~nna/high frequency unit
12 or 42 may be constructed.so as to deal with each of
these frequency bands.
Although the radio contro2. units 13, 43, 51 and 61
are provided with the display 1.6 or the display portion
62, they may be omitted if necessary.
An embodiment of a relay device for use in the mobile
satellite communication according to the present invention
will be described. Fig. 8 shows the embodiment of the
relay device 8 of the present invention. As shown in
Fig. 8, this embodiment is constructed with a satellite
system antenna/high frequency unit 71, a ground system
antenna/high frequency unit 72 and a repeater 73. The
satellite system antenna/high frequency unit 7I, the
ground system antenna/high frequency unit 72 and the
CA 02273142 1999-06-10
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repeater 73 includes a minimurru necessary number of
components as to be described later, respectively, and
so each-of them is compact, light weight and highly
portable.
Interfaces of the satellite system antenna/high
frequency unit 71 and the ground system antenna/high
frequency unit 72 have size anal configuration suitable
to be coupled with interfaces 74 and 75 of the repeater
73, respectively, and, when coupled, the satellite system
antenna/high frequency unit 71 and the ground system
antenna/high frequency unit 72 are fixedly held by the
repeater 73 and internal circuits of these units are
autvrnatically connected to an internal circuit of the
repeater 73.
The repeater 73 is provided with an~external power
source terminal (power source interface) 76 through which
it is connected to a power source adapter through which
the repeater 73 may be fed from, for example, a car
battery.
According to this embodiment, a user usually brings
only the repeater 73 with him and, when necessary, the
interfaces of the satellite system antenna/high frequency
unit 71 and the ground system antenna/high frequency
unit 72 are connected to the interfaces 74 and 75 of
the repeater 73 and the combination of the units 71 and
72~and the repeater 73 is sat in a position which is on
a line of sight of a satellite.
CA 02273142 1999-06-10
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Fig. 9 is a block circuit diagram o.f an embodiment
of a portable relay device according to the present
invention. In Fig. 9, same constructive components as
those shown in Fig. 2 are depicaed by the same reference
numerals, respectively. The satellite system antenna/
high frequency unit 71 is constructed with a satellite
system antenna 111, a satellite: system high frequency
circuit 112 and an interface (I:/F) 113 which is a
connector including an interface circuit. The I/F 113
20 is provided externally of a casing of the unit 71.
The ground system antenna/'high frequency unit 72 is
constructed With a ground system antenna 121, a ground
system high frequency circuit 1.22 and an interface (I/F)
123 provided externally of a casing of the unit 72.
The repeater 73 is constructed with a.first radio control
interface 74, a second radio control interface 75, an
external power source terminal 76 and a system converter
131. The first and second radi,v control interfaces 74
and 75 and the external power source terminal 76 are
provided externally of a casings of the repeater 73.
Fig. l0~is a block diagram showing the system
converter 131. In Fig. 10,' an IF signal for a mobile
satellite system input from,an interface 91 (INTFC 1)
is passed through a receiving I:F circuit 92 (RX IF 1)
and demodulated by a demodulator 93 (DEM 1) to a
baseband signal. The baseband signal is input to a
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baseband processor 96, converged into data necessary for
the mobile ground system and j'.nput to a modulator 97 .
(MOD 2). An output of the MOI> 2 is converted by a
transmission IF circuit 98 (T~: IF Z) into an IF signal
for the mobile ground system and the IF signal is supplied
to an interface 101 (INTFC 2).
On the other hand, a signal conversion from the
mobile ground system to the mobile satellite system is
performed similarly to the above-mentioned conversion.
That is, the IF signal output from the INTFC 2 is input
to a receiving IF circuit 100 (RX IF 2) and then
demodulated by a demodulator 97 (DEM 2).
The demodulation signal is converted into data for
mobile satellite system by the baseband processor 96 and
input to the MOD 1.
The signal modulated by the modulator 95 (MOD 1) is
supplied through the transmission IF circuit 94 (TX IF 1)
to the INTFC 1.
The modulation and demodulation systems employed in
the MOD 1 and the DEM 1 are those suitable for the mobile
satellite system and the modulation and demodulation
systems employed in the MOD 2 and the DEM 2 are those
suitable for the mobile ground system.
The baseband processor 96 outputs a frequency control
signal necessary for the mobile satellite system to the
Rx IF 1 and the TX IF 1 through a line lOZ. On the other
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hand, the baseband processor 96 outputs a frequency
control signal necessary for the mobile ground system
to the RX IF 2 and the TX IF Z through a line 1a3.
The baseband processor 96 further functions to
perform'processing specific to the mobile satellite
system and tre mobile ground system, such as controlling
a billing system, a zone switching system, etc.
As mentioned) the baseband processor 96 includes
various complicated control functions. However, by
utilizing a micro processor, the baseband processor 96
can be realized relatively easily.
An operation of this embodiment wil? be described
with reference to Fig. 8. A signal from a satellite is
received by the antenna 111 of the satellite system
antenna/high frequency unit ?1 shown in Fig. 9 and
converted into the intermediate~ frequency (IF) signal
having a predetermined intermediate fr=_quency by the
high frequency circuit 112 of t:he unit 71. This IF
signal is supplied to the system converter portion 131
of the repeater 73 through the I/F 113 and the I/F 74. . ,
The IF signal is converted intc> an IF signal having
intermediate frequency suitable: for the ground system
antenna/high frequency unit 72, the ZF signal of the
ground system antenna/high freg;uency unit 72 is supplied
to the high frequency.circuit 1.22 of the ground system
antenna/high frequency unit 72 through the I/F 75 and
the I/F 123.
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The high frequency circu9.t 122 frequency-converts
the input IF signal into a signal having a high frequency
within a transmission frequency band suitable for the
mobile ground communication system and transmits it
through the antenna 121. Thin high frequency signal
is received by the ground syst:em~antenna/high frequency
unit 12 of the mobile terminal. ? shown in Figs. 2 to 4.
As described with reference to Fig. 4, the mobile
terminal 7 is set such that, when the interface 12a of
the ground system antenna/high frequency unit 12 is
connected to the interface 14 of the~radio control unit
13, the demodulator 32 and the modulator 34 can perform
the predetermined modulation and demodulation of the
ground system according to the ground system demodulation
control signal a and the modulation control signal b
which are generated by the high frequency circuit 27 and
the baseband processor 33 performs the signal processing
for the ground system.
The transmission signal from the repeater 73 is
received by the antenna 26 and converted into the
predetermined intermediate frequency by the high
frequency circuit 27. The IF ;signal thus obtained
. is supplied through the interfaces 14 and 28 and the
receiving circuit 31 to the demodulator 32 in which
it is normally demodulated. The demodulated signal c
having frequency in the baseband and output from the
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demodulator 32 is supplied, together with the demodulation
clock d, to the baseband processor 33 in which it is .
processed according to the corresponding protocol to
obtain an audio signal or a display data. The auido
signal is supplied to the telephone set 15 and the
display data is displayed by t:he display 16.
On the other hand, for a signal~transmission, a
transmission data input through the key board 17 or an
audio signal input from the telephone set 15 is processed
by the baseband processor 33 according to a transmission
protocol suitable for the ground system antenna/high
frequency unit I2 to obtain the transmission signal a and
the signal a is supplied, together with the transmission
clock f, to the modulator 34 in which it is modulated
according to the switched modulation system.
The modulated wave output from the modulator 34
is converted into an IF signal having predetermined
intermediate frequency by the transmission IF circuit 35
and the IF signay is supplied to the high frequency
circuit 27 through the interfaces 14 and 28 and transmitted
from the antenna 26.
Therefore, according to the present invention, it is
possible to communicate in the satellite system between
the satellite system antenna/hagh frequency unit and the
other and in the mobile ground system between the satellite
system antenna/high frequency unit 71 and the mobile
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terminal 7 through the repeater 73 and the ground system
antenna/high frequency unit 72 or 12. Thus, it is
possible to communicate in the satellite system with
the other even if the mobile terminal 7 shown in Fig. 8
is out of the line of sight of the satellite.
The ground system antenna,/hi.gh frequency unit 72
or l2 may include a cellular communication antenna/high
frequency unit which covers a wide area, a private radio
antenna/high frequency unit which converts a relatively
narrow area such as a factory area, a home radio antenna/
high frequency unit covering a very narrow communication
area such as the so-called cordless telephone or a home
optical co~aunication antenna/lnigh frequency unit.
Therefore, in this embodiment, by connecting the
satellite system antenna/high frequency unit 71 to one
of the interfaces 74 and 75 and connecting the cellular
communication antenna/high frequency unit to the other
interface, it is possible to pE:rform a relay between the
satellite system and the cellular system. Further, by
setting the relay device having the cellular communication
antenna/high frequency unit connected to one of the
interfaces 74 and 75 and the private radio system
antenna/high frequency unit connected to the other
interface in a location covered by the cellular system,
ZS it is possible to communicate between the private radio
system and the cellular system even in an area which is
CA 02273142 1999-06-10
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covered by the private system radio wave but not covered
by the cellular system.
The present invention is not limited to the described
embodiments. For example, in order to accommodate to
vaxious mobile terminals, different radio frequencies
may be used as communication means between the repeater
73 and the mobile satellite terminal 16. Further, the
present. invention can be applied to a radio communication
utilizing infrared ray or light.
Further, by making the repeater 73 foldable or
housing the repea~er 73 within a casing, the portability
of the mobile satellite terminal equipment is improved.
The existing mobile communication system using the mobile
terminal 7 including the antenna/high frequency unit and
the radio control unit integrated therewith includes a
navigation system such as GPS (Global Positioning System)
which utilizes a satellite.
As described hereinbefore, in the mobile terminal of
the present invention, the mobile ground system and the
mobile satellite system can use the radio control unit
commonly and it is possible to communicate with the other
side through either one of the mobile ground communication
system and the mobile satellite communication system by
selectively connecting the interface of the antenna/high
frequency unit of the selected mobile communication system
to the interface of the radio control unit. Therefore,
CA 02273142 1999-06-10
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in use, the mobile terminal equipment of the present
invention is composed of the radio control unit and the
selected antenna/.high frequency unit, which is compact,
light-weight and low cost compared with the conventional
S equipment, and can communicatE~ through either one of the
mobile ground communication system and the mobile satellite
communication system.
Further) since, when the mobile satellite or ground
antenna/high frequency unit is connected to the radio
control unit interface, the circuit portion of the control
unit is automatically switched. to the system 'suitable to
the connected antenna/high frequency unit, there is no
need of any switching operation and any circuit for
switching the system, causing the operability to be
improved and the terminal construction to be simpler.
Further, by performing a bi-directional signal
transmission between the first and second antenna/high
frequency units connected to t:he interfaces of the relay
device of the present invention, the relay device can
communicate between the mobile communication system in
which signal transmission and :receiving is possible by
means of the first antenna/higln frequency unit and the
mobile communication system in which signal transmission
and receiving is possible by means of the second antenna/
ZS high frequency unit. Therefore, it is possible to
communicate With a mobile terminal in an over-the-horizon
< CA 02273142 1999-06-10 _
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location and thus it is possible to perform a mobile
communication through a satellite circuit ever, in
countries in which the traffic: condition of ground
communication is undesirable oi: in an office room without
moving the mobile terminal to a window of the office room.
Further, according to the present invention, since
the two interfaces of the repeater are commonly used by
the interfaces of the respective first and second antenna/
high frequency units, it can relay a communication between
IO various communication systems by selecting tl-.e kind of the
first and second antenna/high l:requency units. Further,
since the relay according to the present invention can be
made compact and light-weight, it can be easily transported
together with the antenna/high frequency units and thus
the over-the-horizon cvmmunicat:ion is facilitated.
