Note: Descriptions are shown in the official language in which they were submitted.
1
Data communication system, railway system comprising such a communication
system and related communication method
Technical field
The invention relates to a data communication system comprising a first
transceiver module for sending-receiving data in the form of a radio signal
and a first radio
transceiver antenna, connected to the first transceiver module and able to be
positioned
near an electric conductor, the first transceiver antenna being configured to
transmit,
respectively to receive, the radio signal in the form of surface radio waves
propagating
along the electric conductor. The data communication system further comprises
a second
radio transceiver antenna, and a second data transceiver module, configured
for
exchanging data with the first transceiver module, the second transceiver
module being
connected to the second antenna.
The invention also relates to a railway system, comprising an electric railway
network comprising at least one catenary system, each catenary system
comprising an
electric conductor, at least one railway vehicle designed to move along the
railway track,
and one such data communication system.
The invention also relates to a method for communicating data in the form of a
radio signal within one such data communication system.
The invention relates to the field of radio communications, for which the
radio
signal is at least partially transmitted in the form of surface waves
propagating along the
electric conductor.
Background
Such systems and data communication method, coupled to an electric grid, are
known from document WO 2006/050331A2. The electric grid comprises a plurality
of
electric conductors electrically connected to one another, each conductor
being positioned
between two maintaining elements of the conductor, and each containing element
being
secured to a vertical mast.
The data communication system comprises a transmission antenna fastened to a
support element and positioned near the electric conductor to transmit a radio
signal
coupling in the form of surface waves along the electric conductor. The data
communication system also comprises several pairs of relay antennas, each pair
of relay
antennas comprising a receiving antenna configured to receive surface waves
propagating along a first electric conductor and a transmission antenna
connected to the
corresponding receiver antenna and configured to retransmit said radio signal
in the form
of surface waves designed to propagate along a second electric conductor. The
data
Date Recue/Date Received 2021-09-02
2
communication system further comprises a receiver antenna configured to
receive the
radio signal transmitted by the transmission antenna at one end of the
electric grid
situated opposite the transmission antenna. The reception antenna is also
positioned near
a corresponding electric conductor and is configured to receive the signal in
the form of
surface waves propagating along the electric conductors of the grid. The
receiving
antenna situated at the end of the grid is further connected to a central
communication
device via traditional radio communication means.
When the user wishes to connect to the data communication system, for example
to transmit data, he approaches a mast of the electric grid and sends said
data to a
transmission antenna fastened to a maintaining element via a first radio
transceiver
contained in an electronic apparatus at his disposal and a second radio
transceiver
connected to the transmission antenna. The first part of the data transmission
is then
done in the form of radio waves transmitted between the first transceiver and
the second
transceiver, and the subsequent part of the data transmission is done via the
transmission
of surface waves along the different electric conductors of said grid.
In other words, the user locally connects to an antenna and radio means, then
the
data are sent along electric conductors in the form of surface waves.
However, such a data communication system is not always very practical for the
user, since the latter is required to connect locally to one of the
transmission antennas
situated near an electric conductor.
Summary
The aim of the invention is therefore to propose a data communication system
making it possible to facilitate the transmission of data via that system,
while using electric
conductors to perform that transmission at least partially in the form of
surface waves
propagating along the electric conductors of the electric grid.
To that end, the invention relates to a data communication system of the
aforementioned type, in which the second transceiver antenna is designed to be
positioned away from the electric conductor, preferably at a distance greater
than 50 cm
from said electric conductor,
the second antenna being configured to receive radio waves which, among the
surface radio waves transmitted by the first antenna, are radiated away from
the electric
conductor and directly from said electric conductor, respectively configured
to transmit
radio waves, some of the waves transmitted by the second antenna being
designed to
propagate along the electric conductor in the form of radio surface waves.
Date Recue/Date Received 2021-09-02
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According to other advantageous aspects of the invention, the data
communication
system comprises one or more of the following features, considered alone or
according to
all technically possible combinations:
- only the first transceiver antenna is designed to be positioned near the
electric
conductor, preferably less than 20 cm from the electric conductor;
- the system further comprises at least one pair of relay antennas, each
pair of
relay antennas comprising a first transceiver relay antenna configured to
receive,
respectively to retransmit, surface waves propagating along a first electric
conductor and
a second transceiver relay antenna, the second relay antenna being connected
to the first
corresponding relay antenna of the pair of antennas and being configured to
retransmit,
respectively to receive, surface waves propagating along a second electric
conductor, the
surface waves along the first conductor corresponding to the surface waves
along the
second electric conductor;
- the system further comprises the electric conductor designed to be
traveled by an
electric current, and the first transceiver antenna is positioned near the
electric conductor,
preferably substantially less than 20 cm from the electric conductor;
- the electric conductor is an electric conductor of a catenary system of a
railway
network;
- the distance between the electric conductor and the second transceiver
antenna
is substantially comprised between 50 cm and 150 cm, preferably substantially
comprised
between 50 cm and 100 cm;
- the electric conductor extends in a longitudinal direction, the first
transceiver
antenna is stationary relative to the electric conductor, and the second
transceiver
antenna is movable relative to the electric conductor in the longitudinal
direction;
- each antenna configured to transmit or receive a radio signal in the form of
surface waves propagating along a corresponding conductor comprises two active
elements, configured for being positioned along the electric conductor and on
either side
of said conductor;
- the active elements have an identical shape, and are designed to be
positioned
symmetrically relative to a vertical plane containing the conductor;
- the active elements each have a curved profile along a vertical plane
parallel to
the electric conductor, the curved profile preferably being concave relative
to the electric
conductor;
- the second transceiver antenna is a directional antenna, and is designed to
be
pointed toward the electric conductor.
Date Recue/Date Received 2021-09-02
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The invention also relates to a railway system comprising an electric railway
network comprising at least one catenary system, each catenary system
comprising an
electric conductor, at least one railway vehicle designed to move along the
railway
network, and a data communication system, wherein the data communication
system is
as defined above.
According to another advantageous aspect, the railway system comprises the
following feature:
- the first transceiver antenna is configured to transmit, respectively to
receive, the
radio signal in the form of surface waves propagating along the conductor of
the
corresponding catenary system, and
at least one railway vehicle comprises the second radio transceiver antenna
and
the second data transceiver module, the second transceiver module being
connected to
the second antenna and configured for exchanging data with the first
transceiver module.
The invention also relates to a method for communicating data in the form of a
radio signal within a data communication system, the data communication system
comprising a first data transceiver module, a first radio transceiver antenna
connected to
the first transceiver module, the first transceiver antenna being positioned
near the electric
conductor, a second radio transceiver antenna and a second data transceiver
module
connected to the second antenna,
the method comprising the following steps:
- transmitting the radio signal, via one module among the first module and
the
second module and via one antenna among the first antenna and the second
antenna,
- transmitting the radio signal in the form of surface waves propagating
along the
electric conductor, and
- receiving said radio signal, via the other antenna from among the first
antenna
and the second antenna and via the other module from among the first module
and the
second module,
wherein the radio signal associated with the second antenna is received in the
form of waves which, among the transmitted surface waves, are radiated away
from the
electric conductor and directly from said electric conductor, respectively
transmitted in the
form of radio waves, some of the waves transmitted by the second antenna being
designed to propagate along the electric conductor in the form of radio
surface waves,
the second antenna being positioned away from the electric conductor,
preferably
at a distance greater than 50 cm from said electric conductor.
The present description also discloses the following aspects:
1.- A data communication system, comprising:
Date Recue/Date Received 2021-09-02
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- a first data transceiver module for transmitting data in the form of a radio
signal,
- a first radio transceiver antenna, connected to the first data
transceiver module
and able to be positioned near an electric conductor, the first radio
transceiver antenna
being configured to transmit, respectively to receive, the radio signal in the
form of surface
waves propagating along the electric conductor,
- a second radio transceiver antenna, and
- a second data transceiver module, configured for exchanging data with the
first
data transceiver module, the second data transceiver module being connected to
the
second radio transceiver antenna,
wherein the second radio transceiver antenna is designed to be positioned away
from the electric conductor;
wherein the second radio transceiver antenna is configured to receive received
radio waves which, among the surface waves transmitted by the first radio
transceiver
antenna, are radiated away from the electric conductor and directly from said
electric
conductor,
wherein the second radio transceiver antenna is configured to emit emitted
radio
waves, some of the emitted radio waves transmitted by the second radio
transceiver
antenna being designed to propagate along the electric conductor in the form
of the
surface waves, and
wherein the first radio transceiver antenna comprises two active elements,
configured for being positioned along the electric conductor and on either
side of said
electric conductor, the two active elements each having a curved profile along
a vertical
plane parallel to the electric conductor.
2.- The data communication system according to aspect 1, wherein only the
first
radio transceiver antenna is designed to be positioned near the electric
conductor.
3.- The data communication system according to aspect 1, wherein the system
further comprises at least one pair of relay antennas, each pair of relay
antennas
comprising a first transceiver relay antenna configured to receive,
respectively to
retransmit, first surface waves propagating along a first electric conductor
and a second
transceiver relay antenna, the second relay antenna being connected to the
first
corresponding relay antenna of the pair of relay antennas and being configured
to
retransmit, respectively to receive, second surface waves propagating along a
second
electric conductor, the first surface waves along the first conductor
corresponding to the
second surface waves along the second electric conductor.
Date Recue/Date Received 2021-09-02
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4. The data communication system according to aspect 3, wherein each relay
antenna comprises two active relay elements, configured for being positioned
along the
electric conductor and on either side of said conductor, the two active relay
elements each
having a curved profile along the vertical plane parallel to the electric
conductor.
5.- The data communication system according to any one of aspects 1 to 4,
wherein the system further comprises the electric conductor designed to be
traveled by an
electric current, and the first radio transceiver antenna is positioned near
the electric
conductor.
6.- The data communication system according to aspect 5, wherein the electric
conductor is an electric conductor of a catenary system of a railway network.
7.- The data communication system according to aspect 5 or 6, wherein the
distance between the electric conductor and the second radio transceiver
antenna is
substantially comprised between 50 cm and 150 cm.
8.- The data communication system according to any one of aspects 5 to 7,
wherein the electric conductor extends in a longitudinal direction, and
wherein the first radio transceiver antenna is stationary relative to the
electric
conductor, and the second radio transceiver antenna is movable relative to the
electric
conductor in the longitudinal direction.
9.- The data communication system according to any one of aspects 1 to 8,
wherein the two active elements have an identical shape, and are designed to
be
positioned symmetrically relative to a vertical plane containing the
conductor.
10.- The data communication system according to any one of aspects 1 to 9,
wherein the curved profile is concave relative to the electric conductor.
11.- The data communication system according to any one of aspects 1 to 10,
wherein the second radio transceiver antenna is a directional antenna, and is
designed to
be pointed toward the electric conductor.
12.- The data communication system according to any one of aspects 1 to 11,
wherein the first radio transceiver antenna is positioned substantially less
than 20 cm from
the electric conductor.
13.- A railway system, comprising:
- an electric railway network comprising at least one catenary system, each
catenary system comprising an electric conductor,
at least one railway vehicle designed to move along the railway network, and
- a data communication system, according to any one of aspects 1 to 12.
Date Recue/Date Received 2022-08-02
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14.- The railway system according to aspect 13, wherein the first radio
transceiver
antenna is configured to transmit, respectively to receive, the radio signal
in the form of
the surface waves propagating along the conductor of the corresponding
catenary system,
and
wherein the at least one railway vehicle comprises the second radio
transceiver
antenna and the second data transceiver module, the second data transceiver
module
being connected to the second radio transceiver antenna and configured for
exchanging
data with the first data transceiver module.
15.- A method for communicating data in the form of a radio signal within a
data
communication system, the data communication system comprising a first data
transceiver module, a first radio transceiver antenna connected to the first
data
transceiver module, the first radio transceiver antenna being positioned near
the electric
conductor, a second radio transceiver antenna and a second data transceiver
module
connected to the second radio transceiver antenna,
the method comprising the following steps:
- transmitting the radio signal, via one data transceiver module among the
first
data transceiver module and the second data transceiver module and via one
radio
transceiver antenna among the first radio transceiver antenna and the second
radio
transceiver antenna,
- transmitting the radio signal in the form of surface waves propagating along
the
electric conductor, and
- receiving said radio signal, via the other radio transceiver antenna from
among
the first radio transceiver antenna and the second radio transceiver antenna
and via the
other data transceiver module from among the first data transceiver module and
the
second data transceiver module,
wherein the radio signal associated with the second radio transceiver antenna
is
received in the form of received radio waves which, among the transmitted
surface waves,
are radiated away from the electric conductor and directly from said electric
conductor,
respectively transmitted in the form of transmitted radio waves, some of the
transmitted
radio waves transmitted by the second radio transceiver antenna being designed
to
propagate along the electric conductor in the form of the surface waves,
the second radio transceiver antenna being positioned away from the electric
conductor, and
the first radio transceiver antenna comprising two active elements, configured
for
being positioned along the electric conductor and on either side of said
conductor, the
Date Recue/Date Received 2022-08-02
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active elements each having a curved profile along a vertical plane parallel
to the electric
conductor.
Brief description of the drawings
These features and advantages of the invention will appear upon reading the
following description, provided solely as a non-limiting example, and done in
reference to
the appended drawings, in which:
- figure 1 is a diagrammatic illustration of a railway system according to
a first
embodiment, the railway system comprising an electric railway network, a
railway vehicle
designed to move along the railway network, and a data communication system,
the data
communication system in particular comprising a first transceiver antenna
positioned near
an electric conductor of the network and configured to transmit, respectively
to receive, a
radio signal in the form of surface waves propagating along the electric
conductors of said
network;
- figure 2 is a diagrammatic illustration of the first antenna of figure 1;
- figure 3 is a flowchart of a data communication method according to the
invention;
- figure 4 is a view similar to that of figure 1 according to a second
embodiment of
the invention; and
- figure 5 is a view similar to that of figure 2 according to the second
embodiment
of the invention.
Detailed description
In figure 1, a railway system 10 comprises an electric railway network 12, a
plurality of railway vehicles 14 and a data communication system 16. A single
railway
vehicle 14 is shown in figure 1 in order to simplify the drawings, and each
rail vehicle 14 is
designed to move along the railway network 12.
The electric railway network 12 comprises at least one catenary system 18,
each
catenary system 18 comprising a plurality of electric conductors 20, the
electric
conductors 20 being connected to each other to ensure continuity of the
transmission of
an electric current through them.
The electric railway network 12 also comprises elements 22 for maintaining
electric
conductors 20 of the catenary system 18, as well as vertical masts 24 to which
the
maintaining elements 22 are fastened. The vertical masts 24 then make it
possible to
position the electric conductors 20 at a predetermined height relative to the
ground on
which rails 26 are fastened for travel of the railway vehicles 14.
Date Recue/Date Received 2021-09-02
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Each railway vehicle 14 is known per se, and is suitable for traveling on the
rails 26
along the electric railway network 12. The railway vehicles 14 can use any
type of power
supply, i.e., external, of the catenary electric power supply type or an
additional rail, for
example, or internal, for instance of the diesel type.
In the example illustrated in figure 1, each railway vehicle 14 is suitable
for being
electrically powered via the electric conductor 20 corresponding to the
catenary system
18. Each railway vehicle 14 for example comprises pantographs 28, each being
configured to be in contact with a corresponding electric conductor 20.
The data communication system 16 comprises a first transceiver module 30 for
transmitting data in the form of a radio signal and a first radio transceiver
antenna 32,
connected to the first transceiver module 30 and positioned near the electric
conductor 20.
The first transceiver antenna 32 is configured to transmit, respectively to
receive, the radio
signal in the form of surface waves propagating along the corresponding
electric
conductor 20.
The data communication system 16 also comprises a second radio transceiver
antenna 34 and a second data transceiver module 36, configured for exchanging
data
with the first transceiver module 30. The second transceiver module 36 is
connected to
the second transceiver antenna 34.
In the example of figure 1, the railway vehicle 14 comprises the second radio
transceiver antenna 34 and the second transceiver module 36, the second
transceiver
module 36 being connected to the second antenna 34 and configured for
receiving data
transmitted by the first transceiver module 30.
The electric conductors 20 also belong to the data communication system 16,
the
electric conductors 20 participating in the transmission of data in the form
of a radio
signal, serving as a propagation support for the surface waves transmitted,
respectively
received, by the first antenna 32.
Each electric conductor 20 extends in a longitudinal direction X, as shown in
figure
2.
The first transceiver module 30 is known per se, and is configured for
converting
the data to be transmitted into an electric signal sent to the first antenna
32, or converting
the electric signal received from the first antenna 32 into data,
respectively.
The first antenna 32 is then configured for transforming the electric signal
received
from the first transceiver module 30 into a radio signal transmitted in the
form of surface
waves along the corresponding electric conductor 20, or transforming a radio
signal
received in the form of surface waves along the corresponding electric
conductor 20 into
an electric signal transmitted to the first transceiver module 30,
respectively.
Date Recue/Date Received 2021-09-02
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The first antenna 32 is positioned close enough to the electric conductor 20
to
allow a propagation of the surface waves along the electric conductor 20, and
in general
to have good coupling with the electric conductor 20. The first antenna 32 is
for example
positioned less than 50 cm from the corresponding electric conductor 20,
preferably less
than 20 cm from said conductor 20.
The first antenna 32 is for example stationary relative to the corresponding
electric
conductor 20. In other words, the position of the first antenna 32 is
unchanged relative to
that of the corresponding electric conductor 20, in particular relative to the
position of the
maintaining elements 22.
In the first embodiment described, only the first transceiver antenna 32 is
positioned near the corresponding electric conductor 20, as shown in figure 1.
In other
words, the only antenna positioned near the electric conductor 20 is the first
antenna 32,
the latter preferably being situated less than 50 cm from said electric
conductor 20.
The first antenna 32 comprises two active elements 40 positioned along the
corresponding electric conductor 20, and on either side of said conductor 20,
as shown in
figure 2.
The first antenna 32 is secured to the mast 24 or, in an alternative that is
not
shown, a maintaining element 22, and the first transceiver module 30 is for
example
positioned near the base of the mast 24 associated with that maintaining
element 22.
According to the invention, the second transceiver antenna 34 is positioned
away
from the electric conductors 20, preferably at a distance greater than 0.5 m
from the
closest electric conductor 20, as shown in figure 1. Additionally, the second
transceiver
antenna 34 is, for example, situated at a distance smaller than 1.5 m from the
closest
electric conductor 20.
The second transceiver antenna 34 is further configured to capture waves that,
among the surface waves transmitted along the electric conductor 20, are next
radiated
away from the electric conductor 20 and directly therefrom, respectively
configured to
transmit radio waves, some of the radio waves transmitted by the second
antenna 34
being designed to propagate along the electric conductor 20 in the form of
radio surface
waves.
The second transceiver antenna 34 that is configured to capture waves radiated
away from the corresponding electric conductor 20, or configured to transmit
waves to the
corresponding electric conductor 20, respectively, is for example a dipolar
antenna, or a
quarter wave antenna, or a slot antenna.
Alternatively, the second antenna 34 is a directional antenna, i.e., focused,
such as
a helical aerial, a patch antenna or a horn antenna. The second antenna 34 is
then
Date Recue/Date Received 2021-09-02
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preferably designed to be pointed toward the electric conductor 20, still more
preferably
oriented in a direction substantially perpendicular to that of the electric
conductor 20.
The second antenna 34 is for example movable relative to the electric
conductor
20 in the longitudinal direction X. In other words, the position of the second
antenna 34
varies in the longitudinal direction X relative to that of the electric
conductor 20, in
particular relative to the position of the maintaining elements 22.
The second transceiver module 36 is known per se, and makes it possible to
convert an electric signal received from the second antenna 34 to which it is
connected
into corresponding data, or to convert data into an electric signal
transmitted to the second
antenna 34, respectively, thereby making it possible to exchange data with the
first
transceiver module 30.
In figure 2, the active elements 40 are preferably identical in form, and
positioned
symmetrically relative to a vertical plane P containing the corresponding
electric conductor
20.
Each active element 40 comprises a first end 42 and a second end 44 in the
longitudinal direction X. Each active element 40 has a length L between the
first and
second ends 42, 44 in the longitudinal direction X. The length L is for
example comprised
between 5 cm and 30 cm, preferably equal to 20 cm, those lengths depending on
the
selected frequency.
Each active element 40 has a height H in a vertical direction Z perpendicular
to the
longitudinal direction X. The height H is for example comprised between 5 cm
and 30 cm,
preferably equal to 30 cm.
Each active element 40 preferably has a profile curved along a vertical plane
parallel to the electric conductor 20, i.e., along a plane containing the
longitudinal X and
vertical Z directions, as shown in figure 2. The curved profile of each active
element 40 is
preferably concave relative to the electric conductor 20.
A space W is present between the active elements 40 of a same antenna, the
space being defined in a transverse direction Y perpendicular to the vertical
plane
containing the longitudinal X and vertical Z directions. The space W is for
example
comprised between 0.5 cm and 10 cm. The space W has a variable value between
the
first and second ends 42, 44, to provide an unbroken transition from the power
supply
impedance at the first end 42, for example equal to 50 ohms, to the
propagation
impedance at the second end 44, for example equal to 377 ohms.
Each active element 40 then preferably has an elongated shape in the
longitudinal
direction X, while having a profile curved along the vertical plane parallel
to the electric
conductor 20.
Date Recue/Date Received 2021-09-02
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This particular shape of each of the active elements 40 makes it possible to
have
the first end 42 of the active element fastened to a corresponding maintaining
element 22,
while having the second end 44 of the active element positioned at an altitude
in the
vertical direction Z substantially equal to the altitude of the electric
conductor 20, due to
the curved profile of each active element 40.
Each active element 40 also makes it possible, due to its elongated shape in
the
longitudinal direction X, to facilitate the coupling with surface waves along
the electric
conductor 20 both in transmission and reception.
The set of the two active elements 40 of the first antenna 32 further has a
generally conical shape from the first ends 42 of the active elements toward
the second
ends 44, which makes it possible to further facilitate the propagation of the
surface waves
along the electric conductor 20.
Each active element 40 is for example made from an electrically conductive
element that is initially planar and has a thickness E for example comprised
between 0.5
cm and 3 cm, preferably equal to 1 cm. Each electrically conductive element,
which is
initially planar, is next curved in order to obtain the curved profile of the
active elements
40.
The operation of the data communication system 16 according to the invention
will
now be described using figures 3, showing a flowchart of a communication
method
according to the invention. For simplification reasons, in the rest of the
description, the
downlink path conventionally corresponds to the path from the first module 30
to the
second module 36, and is described first, then the uplink path will be
described next.
Conventionally and similarly, the uplink path corresponds to the path from the
second
module 36 to the first module 30, the data communication system 16 being
completely
reciprocal.
For the downlink path, during the initial step 100, a radio signal is
transmitted via
the first transceiver module 30 coupled to the first antenna 32, in the form
of surface
waves propagating along the corresponding electric conductor 20, the first
antenna 32
being positioned near the electric conductor 20.
The radio signal then propagates during step 110 in the form of surface waves
along the electric conductor 20, and from the first antenna 32. During this
transmission
step 110, as the waves propagate on the surface of the electric conductor 20,
some of
those waves are gradually radiated further and further away from the electric
conductor 20
and directly from said electric conductor 20.
The second transceiver antenna 34 is then able, during step 120, to receive
said
waves radiated away from the electric conductor 20, the second antenna 34
being
Date Recue/Date Received 2021-09-02
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positioned away from said electric conductor 20 and configured to capture
those radiated
waves.
During that reception step 120, the radio signal received by the second
antenna 34
is then sent to the second transceiver module 36 to be converted into an
electric signal
delivered to the output of the second transceiver module 36. The data
transmitted by the
first transceiver module 30 and the first antenna 32 are thus directly
received inside the
railway vehicle 14 by means of the second transceiver module 36 coupled to the
second
antenna 34.
For the uplink path, during the transmission step 100, a radio signal is
transmitted
via the second transceiver module 36 coupled to the second antenna 34, in the
form of
radio waves, some of the waves transmitted by the second antenna 34 being
designed to
propagate in the form of radio surface waves along the corresponding electric
conductor
20.
The radio signal then propagates during step 110 in the form of surface waves
along the electric conductor 20, and toward the first antenna 32. During this
transmission
step 110, the waves propagate on the surface of the electric conductor 20
toward the first
antenna 32.
The first antenna 32 is then able, during the reception step 120, to receive
said
surface waves propagating along the electric conductor 20, the first antenna
32 being
positioned near said electric conductor 20 and configured to capture those
surface waves.
During this reception step 120, the radio signal received by the first antenna
32 is
then transmitted to the first transceiver module 30 to be converted into an
electric signal
delivered at the output of the first transceiver module 30. The data
transmitted by the
second transceiver module 36 and the second antenna 34 are thus received by
the first
transceiver module 30 connected to the first antenna 32.
This then makes it possible to facilitate the communication of the data while
retaining, on part of the path between the first transceiver module 30 and the
second
transceiver module 36, the transmission of radio waves in the form of surface
waves along
the electric conductor 20. This then makes it possible to obtain a significant
range for the
transmission of the radio signal, while facilitating the reception of the data
inside the
railway vehicle 14, or the transmission of data from the inside of the railway
vehicle 14,
respectively.
Unlike the data communication system of the state of the art, the data
communication system 16 according to the invention does not require the user
to connect
locally via a radio means to a transceiver antenna for surface waves situated
near a mast
of the electric railway network. The data communication system 16 according to
the
Date Recue/Date Received 2021-09-02
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invention thus facilitates the reception, respectively the transmission, of
data at all points
of the electric conductor 20.
At the railway vehicle, the data communication system 16 allows the use of
traditional antennas, the second transceiver antenna 34 for example being of
the
omnidirectional type.
Alternatively, in order to obtain better performance, the second transceiver
antenna 34 is preferably directional, or focused, pointing toward the electric
conductor 20.
Positioning the second transceiver antenna 34 away from the electric
conductors
20, preferably at a distance greater than 50 cm from the closest electric
conductor 20,
further makes it possible to have a safety distance between the railway
vehicle 14 and the
electric conductor 20, when the second transceiver antenna 34 is fastened to
the railway
vehicle 14.
Figures 4 and 5 illustrate a second embodiment of the invention, in which the
elements identical to those of the first embodiment, previously described, are
identified by
identical references, and are not described again.
According to this second embodiment, the data communication system 16 further
comprises at least one pair 200 of relay antennas, each pair of relay antennas
200
comprising a first transceiver relay antenna 202 configured to receive,
respectively to
retransmit, surface waves propagating along a first electric conductor 20A and
a second
transceiver relay antenna 204. The second transceiver relay antenna 204 is
connected to
the corresponding first transceiver relay antenna 202 of said pair of antennas
200, and is
configured to retransmit, respectively to receive, surface waves propagating
along a
second electric conductor 20B, the surface waves along the first conductor 20A
corresponding to the surface waves along the second electric conductor 20B.
For each pair of relay antennas 200, the first transceiver relay antenna 202
and the
second transceiver relay antenna 204 each have a form similar to that of the
first
transceiver antenna 32.
The first relay reception antenna 202 and the second transceiver relay antenna
204 for example are in the form of the first antenna 32 previously described
with respect
to figure 2, and then each comprise the two active elements 40, as shown in
figure 5.
In the example of figure 4, the first transceiver antenna 32 and the first
relay
antenna 202 are each positioned at one end of the first electric conductor 20A
while
extending globally in the longitudinal direction X and being oriented in
opposite directions.
The second relay antenna 204, coupled to the first relay antenna 202 situated
near
the first electric conductor 20A, is situated near the second electric
conductor 20B, while
Date Recue/Date Received 2021-09-02
15
being oriented in the same direction as the first transceiver antenna 32,
while also
extending globally in the longitudinal direction X.
The pair of relay antennas 200 then makes it possible to retransmit the
surface
waves initially propagating along the first conductor 20A toward the second
electric
conductor 20B, and conversely to retransmit the surface waves propagating
initially along
the second electric conductor 20B toward the first conductor 20A.
For the downlink path, the first relay antenna 202 is able to capture the
surface
waves propagating along the first conductor 20A, then the second relay antenna
204 that
is coupled to the first relay antenna 202 is able to retransmit that same
radio signal in the
form of surface waves propagating along the second electric conductor 20B.
Conversely, for the uplink path, the second relay antenna 204 is able to
capture
the surface waves propagating along the second conductor 20B, then the first
relay
antenna 202 that is coupled to the second relay antenna 204 is able to
retransmit that
same radio signal in the form of surface waves propagating along the first
electric
conductor 20A, to the first transceiver antenna 32.
The relay antennas 202, 204 are also called retransmission antennas, or
repeater
antennas, those antennas 202, 204 making it possible to repeat, along the
second
conductor 20B, the radio signal initially propagating along the first
conductor 20A in the
form of surface waves, and reciprocally along the first conductor 20A, the
radio signal
propagating initially along the second conductor 20B in the form of surface
waves.
Each pair of relay antennas 200 then makes it possible to further increase the
propagation distance of the radio signal along the electric conductors 20A,
20B, i.e., to
generally increase the transmission range of the radio signal via that data
communication
system 16.
Each pair of relay antennas 200 is secured to at least one maintaining element
22,
and is preferably positioned near a mast of the electric railway network 12.
The operation of the data communication system 16 according to this second
embodiment is then similar to that of the data communication system 16
according to the
first embodiment.
For the downlink path, the transmission of the radio signal is always done via
the
first transceiver antenna 32 associated with the first transceiver module 30,
and the final
reception of the data is always done via the second transceiver antenna 34
coupled to the
second transceiver module 36, with the second transceiver module 34 positioned
away
from the various electric conductors 20A, 20B.
Reciprocally, for the uplink path, the transmission of the radio signal is
done via the
second transceiver antenna 34 associated with the second transceiver module
36, and
Date Recue/Date Received 2021-09-02
16
the final reception of data is done via the first transceiver antenna 32
coupled to the first
transceiver module 30.
According to this second embodiment, the transmission step 110 further
comprises
a retransmission of the surface waves from one electric conductor 20A to the
other
electric conductor 20B by means of a pair of corresponding relay antennas 200,
each pair
of relay antennas 200 making it possible to propagate the surface waves from
one electric
conductor to the other.
The advantages of this second embodiment comprise the advantages of the first
embodiment previously described.
The data communication system 16 according to this second embodiment further
makes it possible to increase the transmission range of the data in the form
of radio
signals, by the pairs of relay antennas 200 capable of ensuring continuity in
the
propagation of the surface waves along the electric conductors despite the
passage from
the first conductor 20A to the second conductor 20B. This effect is in
particular obtained
when the electric conductors 20 are part of the catenary system 18 of the
electric railway
network.
One can thus see that the data communication system 16 according to the
invention makes it possible to have a large distance between the first
transceiver antenna
32 and the second transceiver antenna 34, typically a distance greater than 1
km, while
improving the ease of communication of the data, the second transceiver
antenna 34 for
example being fastened to a railway vehicle 14, while being coupled to the
second
transceiver module 36 positioned inside said railway vehicle.
This then makes it possible to receive the data inside the railway vehicle 14,
including when it is in motion along the electric railway network 12.
Date Recue/Date Received 2021-09-02
