JPH10190587A - Transmission/reception system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce transmission loss in signal transmission between a transmission- antenna/reception-antenna and a closed space such as a tunnel or the like by receiving radiated electromagnetic waves, modulating the intensity of incident light corresponding to the voltage of electric signals and emitting it. SOLUTION: The incident light of an optical modulator 22 passed from a light source 23 through an optical fiber 26 or the like is made incident on an incident/ emission optical waveguide, then energy is divided into two phase shift optical waveguides and it is reflected in a reflection part and returned to an original optical path. By signals from the reception antenna 21, the voltage is applied to a modulation electrode and electric field components mutually opposite to a depth direction are generated in the two phase shift waveguides. As a result, a phase difference is generated corresponding to the size of an applied voltage between two optical waves and the intensity of the emission light emitted again from an incident/emission optical waveguide end is changed corresponding to applied voltage intensity. The emission light is separated from the incident light by an optical circulator 27, made incident on a photoelectric converter 24 installed in a radio wave blind area or near it and converted to the electric signals.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention, which is also referred to as a radio wave insensitive area, enables various communication including two-way communication between tunnels and underground shopping centers where it is difficult to receive and transmit radio waves and wide open spaces. And a transmitting / receiving system.

[0002]

2. Description of the Related Art Broadcasting and telecommunications
Increasingly important, the transmission and transmission of information
Communication networks are being developed. As a result, means of broadcasting and communication are being secured everywhere, including in mountains and on remote islands.

However, at present, the means for using broadcasting and communication in tunnels, underground shopping centers, and the like are still generally poor. FIG.
Between a space where radio waves are insensitive, such as tunnels and underground malls, or a space where radio waves are obstructed (hereinafter referred to as a closed space) and a normal space where radio waves can be transmitted and received freely (hereinafter referred to as a widely open space) FIG. 3 is a diagram schematically showing a method of a transmitting / receiving means.

A receiving antenna 21 and a transmitting antenna 11 installed in a receivable area such as a mountaintop have a function of transmitting information between a closed space and a wide open space. Then, the information received by the receiving antenna 21 is radiated again as a radio wave 20 to the space through the leaky coaxial cable 29 laid in the closed space, and is received by each transceiver 31.

On the other hand, information radiated as radio waves from each transceiver 31 in the closed space is received by a leaky coaxial cable 30 similarly laid in the space separately from the leaky coaxial cable 29 for reception. , Transmitting antenna 1
1 and radiated as electromagnetic waves toward a wide open space.

As described above, communication between a closed space such as a tunnel or an underground shopping mall and a widely open space has been maintained by such a method.

[0007]

However, for example, a transmitting antenna 1 installed in a receivable area at the top of a mountain is required.
1. The method of transmitting a long distance from the receiving antenna 21 to the tunnel by using the coaxial cable 32 has a large signal attenuation, invasion of external noise into the coaxial cable 32,
There have been problems such as the possibility of damage to the transmission path itself due to lightning.

In the conventional system for transmitting and receiving radio waves to and from the transceiver 31 again through the leaky coaxial cables 29 and 30 laid in the closed space, the leaky coaxial cable 2
Transmission loss of 9 and 30 is large. Therefore, in a long tunnel or the like, it is necessary to install the amplifiers 15 and 25 at an interval of about 500 m, which is a problem in smoothly installing and maintaining the system.

Furthermore, the problem of narrow frequency bands limits the types of information that can be used, and is far from being able to enjoy various broadcasts and communications.

The present invention realizes a transmission / reception system in which transmission loss in signal transmission between a transmitting antenna, a receiving antenna, and a closed space such as a tunnel is reduced, and furthermore, a transmission path system in a closed space has a low loss and a wide area. Has a frequency band,
It is an object of the present invention to provide a transmission / reception system that can fully enjoy the diversity of broadcasting even in a closed space such as a tunnel or an underground shopping mall, and enables two-way communication between a closed space and a wide open space.

[0011]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a transmitting unit for receiving an electromagnetic wave radiated from a transceiver and radiating the electromagnetic wave again from a transmitting antenna, and receiving the electromagnetic wave from a transmitting antenna. In a transmission / reception system including a reception unit that radiates an electric signal again as an electromagnetic wave, the transmission unit receives the electromagnetic wave radiated from the transmission antenna, the light source, and the transceiver, and generates incident light according to the voltage of the electric signal. The transmission unit includes a repeater including an optical modulator that modulates intensity and emits light, and a transmission transmission line system including a transmission line including an optical fiber including a photoelectric converter connected to a transmission antenna. This is a transmission / reception system including an antenna, a light source, an optical modulator including a photoelectric converter, and a reception transmission line system including a transmission line including an optical fiber.

Further, according to the present invention, in the transmission / reception system, the reception unit includes a reception antenna, a light source, an optical modulator for modulating a voltage signal from the reception antenna to light intensity, a transmission line including an optical fiber, and a photoelectric conversion device. And a receiving transmission line system including one or more electromagnetic radiators with a transmitter.

Further, the present invention uses an optical modulator comprising an optical waveguide element, and an optical amplifier is provided in a transmission transmission line system and / or a reception transmission line system, or a transmission unit and a reception unit share one light source. This is a transmission / reception system having such a configuration.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below.
This will be described with reference to the drawings.

(Embodiment 1) FIG. 1 is a diagram showing a transmission / reception system according to an embodiment of the present invention. FIG.
And FIG. 5, respectively, used in the transmitting and receiving system,
FIG. 3 is a diagram illustrating a configuration of a so-called reflection type optical modulator and a configuration of a transmission type optical modulator.

In FIG. 1, a transmitting antenna 11 and a receiving antenna 21 are installed in an area where radio waves can be received, such as a mountaintop.

First, the receiving section will be described. The information received by the receiving antenna 21 is modulated by the optical modulator 22 into a light intensity signal. As shown in FIG. 4, the optical modulator 22 includes an input / output optical waveguide 52 on a lithium niobate single crystal substrate 51 cut out perpendicular to the c-axis.
A phase shift optical waveguide 55 branched and coupled therefrom, and a reflection portion 57 formed on the other end face of the two phase shift optical waveguides 55 are formed.

An optical fiber 26 is coupled to the end of the input / output optical waveguide 52, and a pair of divided modulation electrodes 56 are provided on the phase shift optical waveguide 55 and connected to the receiving antenna 21. Have been.

As shown in FIG. 3, incident light from the light source 23 of FIG. 1 through the optical fiber 26 and the like to the optical modulator 22 enters the input / output optical waveguide 52, and then enters the two phase shift optical waveguides 55. The energy is split, reflected by the reflector 57, and returns to the original optical path. A voltage is applied to the modulation electrode 56 by a signal from the receiving antenna 21, and electric field components in the two phase-shifted optical waveguides 55 are generated in opposite directions in the depth direction.

As a result, a phase difference occurs between the two light waves according to the magnitude of the applied electric field, and the intensity of the outgoing light emitted again from the end of the input / output optical waveguide 52 changes according to the applied electric field intensity. The outgoing light is separated from the incoming light by the optical circulator 27, and as shown in FIG. 1, enters the photoelectric converter 24 installed in or near the radio wave insensitive area, and is converted into an electric signal.

The output electric signal of the photoelectric converter 24 propagates through a leaky coaxial cable 29 laid in a radio wave insensitive area such as a tunnel or an underground shopping mall via a coaxial cable, and passes through the leaky coaxial cable 29 as electromagnetic waves to the space. It is radiated again and received by the transceiver 31.

Next, the transmitting section will be described. The radio wave radiated from the transceiver 31 in the closed space is converted from an electric signal to an optical signal by the nearest repeater 19 among the plurality of repeaters 19 provided on the transmission line at regular intervals.

The converted optical signal propagates through a transmission line including an optical fiber 16 laid in the space, and enters the photoelectric converter 14. Further, the optical signal is converted into an electric signal again by the photoelectric converter 14, amplified by the amplifier 15, and then emitted from the transmitting antenna 11 as an electromagnetic wave toward a wide open space.

The light emitted from the light source 13 composed of a semiconductor laser, which is connected to one end of the transmission line of the optical fiber 16, propagates through the optical fiber 16 and enters the optical modulator constituting the repeater 19. You.

As shown in FIG. 5, the optical modulator constituting the repeater 19 has a branch interference type optical waveguide formed on a lithium niobate single crystal substrate 61 cut out perpendicularly to the c-axis. On the two phase shift optical waveguides 65 of the branch interference optical waveguide, a pair of divided modulation electrodes 66 are formed.

The modulation electrode 66 has a repeater antenna 34
Is connected. An optical fiber 16 is coupled to each end of the incident optical waveguide 63 and the exit optical waveguide 64.

In the case of a long tunnel or the like, as shown in FIG.
9 are connected in series and the repeater 1 closest to the transceiver 31
Communication is secured through 9.

As shown in FIG. 3, the light from the light source 13 shown in FIG. 1 that has passed through the optical fiber 16 is incident on the incident optical waveguide 63, then the energy is split into two phase-shifted optical waveguides 65, and the output optical waveguide 65 is emitted. 64 and the next optical fiber 1
6 is transmitted.

According to the signal from the antenna 34 of the repeater,
When a voltage is applied to the modulation electrode 66, electric field components are generated in the two phase-shifted optical waveguides 65 in directions opposite to each other in the depth direction.

As a result, a phase difference occurs between the two light waves in accordance with the magnitude of the applied electric field, and the intensity of the outgoing light emitted from the end of the outgoing optical waveguide 64 changes according to the applied electric field intensity.

In the transmission / reception system according to the present invention, the transmission unit and the reception unit use the optical fibers 16 and 26 as signal transmission paths for a long distance from the transmission antenna 11 and the reception antenna 21 to the closed space, respectively, to thereby reduce transmission loss. Therefore, there is no risk of external noise entering the transmission line or damage to the transmission line itself due to lightning strikes.

Further, since the transmission unit has a small transmission loss in the transmission line due to the optical fiber 16 even in a closed space, signal amplification measures are not required up to 5 km, or even if installation is necessary, The feature is that the interval can be significantly increased as compared with the leaky coaxial cable.

(Embodiment 2) FIG. 2 is a diagram showing a transmission / reception system according to another embodiment of the present invention. FIG.
FIG. 14 is a diagram showing a transmission / reception system which is still another form based on the present embodiment.

First, the receiving section will be described. The information received by the receiving antenna 21 is modulated by the optical modulator 22 from a voltage signal to a light intensity signal. Optical modulator 2
The outgoing light of No. 2 propagates through the optical fiber 26 transmission line laid inside the radio wave insensitive area. In the radio wave insensitive area, an electromagnetic radiator 18 having a photoelectric converter 24 is connected to the transmission line of the optical fiber 26 at regular intervals, and is radiated again into the space as an electromagnetic wave.

Next, the transmitting section is basically the same as that of the first embodiment. An optical amplifier 36 is added to the transmission path of the optical fiber 16. This is particularly effective when the attenuation of an optical signal due to propagation is inevitable, such as in a long tunnel.

As the optical amplifier 36, an erbium-doped optical fiber amplifier, a semiconductor optical amplifier or the like is suitable. In the case of these optical amplifiers, the installation interval may be about 5 km. In addition,
Obviously, the addition of the optical amplifier is also effective for the transmission line of the optical fiber 26 in the receiving section.

The second embodiment is most different from the first embodiment in that, in a closed space, an electric signal is converted into optical information and transmitted, including a reception transmission line system, in a closed space. As a result, transmission loss can be reduced as well as broadband communication becomes possible, and if a receiving antenna and a transmitting antenna suitable for the frequency band to be used are provided, it is technically possible to transmit and receive a frequency band from a DC signal to 3 GHz. It becomes possible.

From the AM radio broadcast wave of several hundred kHz band, 1.
Up to 9GHz PHS (Personal Handy Horn), all the broadcast and communication frequency bands we can enjoy now, as well as in open space,
It can also be used in closed spaces.

The transmission / reception system shown in FIG.
The transmission unit and the reception unit share one light source 23 while using the transmission / reception system according to the present invention shown in FIG. 2 essentially, and the branched outgoing light is used as each incident light.
If the light source has a sufficient output, one light source has advantages such as easy maintenance.

The optical modulator according to the first embodiment and the optical modulator as a repeater according to the second embodiment employ a so-called reflection type optical modulator and a transmission type optical modulator, respectively. There is no inevitable reason to use them properly. Further, the optical modulator may be an optical waveguide element constructed on a substrate made of lithium niobate having an X-plane as a main surface or a material exhibiting another electro-optical effect.

[0042]

As described above, according to the present invention,
A transmission / reception system that reduces transmission loss in signal transmission between a transmitting antenna, a receiving antenna, and a closed space such as a tunnel is realized. In a closed space such as an underground mall or the like, the diversity of broadcasting can be fully enjoyed, and a transmission / reception system that enables two-way communication between the closed space and the wide open space has been realized.

[Brief description of the drawings]

FIG. 1 is a diagram showing a transmission / reception system according to an embodiment of the present invention.

FIG. 2 is a diagram showing a transmission / reception system according to another embodiment of the present invention;

FIG. 3 is a diagram showing a transmission / reception system as still another embodiment of the present invention.

FIG. 4 is a diagram showing a configuration of a reflection type optical modulator.

FIG. 5 is a diagram showing a configuration of a transmission optical modulator.

FIG. 6 is a diagram schematically showing a method of a conventional transmitting / receiving means.

[Explanation of symbols]

 Reference Signs List 11 transmitting antenna 12, 22 optical modulator 13, 23 light source 14, 24 photoelectric converter 15, 25 amplifier 16, 26 optical fiber 18 (with photoelectric converter) electromagnetic radiator 19 repeater 20 radio wave 21 receiving antenna 27 optical circulator 28 Optical splitter 29, 30 Leaky coaxial cable 31 Transceiver 32 Coaxial cable 34 Antenna 36 Optical amplifier 51, 61 Substrate 52 Input / output optical waveguide 55, 65 Phase shift optical waveguide 56, 66 Modulation electrode 57 Reflector 63 Incident optical waveguide 64 Emission Optical waveguide

Claims (5)

[Claims] 1. A transmission / reception unit that receives an electromagnetic wave radiated from a transceiver and radiates the electromagnetic wave again from a transmission antenna, and a reception unit that radiates an electric signal received by the reception antenna again as an electromagnetic wave. In the system, the transmission unit is a relay comprising the transmission antenna, a light source, and an optical modulator that receives electromagnetic waves radiated from the transceiver and modulates the intensity of incident light according to the voltage of an electric signal to emit the light. And a transmission transmission line system including a transmission line formed of an optical fiber having a photoelectric converter connected to the transmission antenna, and the reception unit includes the reception antenna, a light source, and a photoelectric converter. And a receiving transmission line system including a transmission line formed of an optical fiber. 2. A transmission / reception unit which receives an electromagnetic wave radiated from a transceiver and radiates the electromagnetic wave again from a transmission antenna, and a reception unit which radiates an electric signal received by the reception antenna again as an electromagnetic wave. In the system, the transmission unit is a relay comprising the transmission antenna, a light source, and an optical modulator that receives electromagnetic waves radiated from the transceiver and modulates the intensity of incident light according to the voltage of an electric signal to emit the light. Device, and a transmission transmission line system including a transmission line composed of an optical fiber having a photoelectric converter connected to the transmission antenna, the reception unit, the reception antenna, a light source, from the reception antenna From an optical modulator that modulates a voltage signal to light intensity, a transmission line composed of an optical fiber, and a reception transmission line system including one or more electromagnetic radiators with a photoelectric converter A transmission / reception system characterized by being configured. 3. The transmission system according to claim 1, wherein the optical modulator comprises an optical waveguide element. 4. The transmission / reception system according to claim 1, wherein at least one of the transmission unit and the reception unit includes an optical amplifier. 5. The transmission / reception system according to claim 1, wherein the light source of the transmission unit and the light source of the reception unit are one light source.