JP2790769B2 - Medium-wave radio transmission method in tunnel - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a medium wave in an underground mall or an underground parking lot, particularly in a tunnel where an AM medium wave radio can be listened in a closed area of a broadcast radio wave such as in a subway track or an automobile road tunnel. The present invention relates to a radio transmission method. Here, the term "tunnel" includes not only subway tracks and road tunnels, but also pedestrian underground passages in underground shopping malls, underground connecting passages, and the like, and these are hereinafter collectively referred to as tunnels.

[0002]

2. Description of the Related Art When an AM radio wave is received on the roof of an existing building and the received radio wave is transmitted to the basement, a coaxial cable for transmitting a medium-frequency radio is installed in the existing building from the roof in the prior art. It was going to be newly added to the basement. In addition, it was necessary to construct a new guide line on the wall to re-radiate radio waves underground.

[0003]

In the prior art, since the laying is carried out in an existing building, it is generally difficult and requires a large amount of cost. Therefore, an object of the present invention is to couple a medium-wave radio wave to an existing wiring (a power line, a telephone line, a coaxial cable for common use, etc.) or a pipe extending from the upper part of the ground facility to the basement via a coupler and transmitting the same. It is another object of the present invention to provide a method of transmitting a medium-wave radio signal into a tunnel in which the above-mentioned problems are eliminated, which can be extracted and re-radiated in an underground tunnel.

[0004]

In order to achieve this object, the present invention provides a method for transmitting a medium-frequency radio wave into a tunnel by installing a receiving antenna for receiving a medium-frequency radio wave whose amplitude has been modulated, above a ground facility. Receiving a medium-wave radio wave, and converting the received medium-wave radio wave into a first signal having level adjustment means, modulated wave phase shift means, and impedance matching means.
And a first coupler which is an electromagnetic coupling means constituted by sandwiching at least two U-shaped ferrite cores while winding the primary line and the secondary line in parallel without being wound, and Connect to existing wiring or piping,
While transmitting to a predetermined underground, the medium-wave radio wave transmitted to the predetermined underground, the second coupler as the electromagnetic coupling means having the same configuration as the first coupler, and the first booster and Via a second booster provided with the same means, and further via a capacitor connected to the output of the second booster, the existing linear wiring or piping is coupled and fed in the predetermined underground tunnel, The medium-wave radio wave is re-emitted from the fed linear wiring or pipe.

[0005]

According to the method of the present invention, the existing wiring or piping at the ground facility is used for transmission of radio waves. For example, for re-radiation underground, the existing wiring or piping is used to newly establish a coaxial cable. Since there is no need to lay cables or to newly extend a guide wire on a wall or the like, there is an advantage that the construction is simplified and the cost is greatly reduced.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 shows a first embodiment according to the transmission method of the present invention, that is, a system diagram in the case where radio wave radiation underground uses a current-carrying power line already arranged almost linearly in a tunnel. .

Specifically, the tunnel 13 shown here may be supposed to be in a tunnel in which a subway track is laid, in an automobile road tunnel, or in a substantially straight underground passage or underground walkway in an underground mall. The facility where the receiving antenna 1 to be used at this time is to be installed may be a station building along a subway track, an automobile road tunnel, or a building near an entrance such as an underground passage.

In FIG. 1, an antenna 1 is a medium-wave radio receiving antenna whose amplitude is modulated. In the method of the present invention, the receiving antenna 1 is newly installed on the roof of a predetermined existing building on the ground. The radio wave received by the antenna 1 is then amplified to a sufficiently high level by the booster 2-1. The amplified radio wave is coupled to an existing co-listening coaxial cable (5C-2V) 4 in this example via a coupler 3-1 described later. At this time, the cable 4 shown here is not limited to this, but may be any electric wire such as a power line, a telephone line, etc., which leads from the roof to a predetermined basement, preferably to the above-mentioned tunnel. Depending on the case, a conductive pipe may be used.

However, what should be noted here is this wiring,
Since the piping is a secondary line of the coupler 3-1 to be described later, a loop circuit including a stray capacitance between the ground wire and the ground is formed with respect to a target medium frequency radio frequency radio wave. Must be done. When the wiring 4 is a coaxial cable for co-listening as in the example shown in FIG. 1, the outer conductors are a booster 5 for FM co-listening on the roof and a front end 6 in the basement.
Are grounded at the points (1) and (2), the wiring and the ground make the secondary line of the coupler loop-like, which is convenient.

[0010] The medium-frequency radio wave introduced from the rooftop to a predetermined underground is then radiated into the tunnel through a light line already installed in the tunnel. That is, another coupler 3 is located near the underground end of the cable 4 shown in FIG.
2 is amplified again by another booster 2-2, and is commercialized (for example, 6600V, three-phase).
7, a high-voltage transformer (200 V, three-phase) 8, and a wiring 14 for an illumination light 15 in a tunnel prepared in the order of a switchboard 10 are supplied with power via a capacitor 11 through a contact 12. At this time, the radiation of the radio wave from the illumination lamp wiring 14 may be considered to be the normal transmission of the medium-wave radio, and that the antenna of the vertical linear transmission antenna is made to sway from vertical to positive horizontally, and the radiation efficiency is vertical. Although it is deteriorated compared to the antenna, it is possible to obtain sufficient electromagnetic field strength for listening to the medium wave radio in the tunnel.

Thus, the radio wave radiated by the illumination lamp wiring 14 enables good listening of the medium-wave radio in the tunnel.
It was confirmed that radio waves could be transmitted well up to about m. In addition, it is added here that the frequency of the medium-wave radio wave to be covered by the method of the present invention is about 100 kHz to 5 MHz.

Japanese Patent Application No. 5-234 previously filed by the present applicants
The configuration described in FIG. 1 of the invention "Medium-wave radio transmission method" to be No. 892 is almost similar to the configuration of the present invention, but a line for radiating the medium-frequency radio wave at a predetermined basement is newly provided or an existing loop. It is different in the shape of the wiring and the conductive piping. That is, if the loop-shaped line is present, the medium-wave radio wave can be further coupled to the line via the coupling coupler 3-3 (see FIG. 1 of Japanese Patent Application No. 5-234892) to cause the line to radiate. it can.

A switchboard 1 as shown in FIG.
In the case where the lighting wiring 14 through 0 is used for radiation,
It is good when power is supplied through the switchboard (because there is a ground on the primary side), but when the switchboard is switched off and de-energized, a loop-shaped line is formed only by the wiring 14 ahead. Is not configured. Therefore, coupler 3-3
Cannot be used. In view of such a case, the present inventors have proposed to supply a radio wave to a radiation line via a capacitor as in this application. When the switchboard of the switchboard is turned on, a loop-shaped line is formed by the ground 9 on the primary side, the wiring 14 for the lighting, and the stray capacitance of this wiring with respect to the ground. Can be used.

The second embodiment of the present invention relates to a case in which radio waves are radiated underground by using a ladder or the like on which electric wires already arranged substantially linearly in a tunnel are mounted. Although a system diagram is not shown in this case, the description is simple and the ladder itself is in a non-energized state. Therefore, the output line of the booster 2-2 shown in FIG. It can be connected to supply power.

When the installation location of the antenna 1 and the booster 2-1 is close to the feeding point in the tunnel,
It is also possible to omit the transmission line 4 and immediately supply power to the radiating conductor in the tunnel from the output of the booster 2-1.

FIG. 2 is a diagram showing an example of the above-mentioned coupler configuration. A primary line 21 and a secondary line 22 such as an existing coaxial cable are composed of two U-shaped ferrite cores 20-1 and 20-2.
Is used to couple the medium-frequency radio waves. In terms of the size of the ferrite, an inner diameter of 13 mmφ, an outer diameter of 26 mmφ, and a longitudinal length of 28 mm were used in the experiment. It should be noted here that the electromagnetic coupling between the primary line 21 and the secondary line 22 is achieved by a simple operation of being sandwiched by a U-shaped ferrite core having a simple structure, so that the secondary line is activated. That is, the purpose can be easily achieved even in a line state. In addition, by arranging a plurality of ferrite cores in cascade along the coupling portion, even if the secondary line (loop-shaped line) has a low impedance, the degree of coupling is increased and power is efficiently transmitted. Can be.

The third embodiment of the present invention is directed to a case where a medium-frequency radio wave is re-radiated into a tunnel such as a highway as shown in FIG. The receiving antenna 31 is installed on the ground above a tunnel or on the roof of a nearby building. The output of the antenna 31 is applied to a booster 33 for re-radiation via a feeder 32, and the output of the booster 33 is connected to an existing lighting wire 35 in a tunnel 34, a pipe for fire extinguishing equipment, a pipe for a wire, and the like. To re-radiate radio waves. The booster 33 is provided with at least one phase shifter or delay unit 36 for the modulated wave. Preferably, the phase shifter 36, the level adjuster 37, and the impedance matching unit 3 are provided for each radio wave channel.
8 is provided. A lumped constant circuit such as L and C can be used as a phase shifter or a delay unit for the modulated wave, and can be performed by a known method. In addition, a delay element such as a SAW or a CCD can be used.

Depending on the installation location of the receiving antenna 31, re-radiated waves may be received and oscillation may occur. Further, depending on the position in the tunnel, direct waves and re-radiated waves may be mixed, and the phase shifter 36 may be used. In order to prevent the oscillation and optimize the radio wave electric field distribution in the tunnel by giving the optimum phase shift to the re-radiated wave. Desirably, this is performed for each channel, and the level adjustment 37
In addition, the impedance matching 38 is used to adjust the booster 33 to the existing electric wire under the optimum impedance matching conditions.
Combine the outputs of This enables good medium-wave reception in the tunnel. As a result of the experiment, when the output of the booster 33 was 0.2 W, it was confirmed that the medium-wave radio could be satisfactorily received over the entire 750 m long tunnel. A booster 2-1 and / or 2-2 which uses the same booster provided with the level adjusting means, the modulated wave phase shifting means and the impedance matching means described in the third embodiment in the first embodiment. It can also be used for

Although several embodiments of the present invention have been described with reference to FIGS. 1, 2, and 3, the present invention is not limited to these embodiments, and the invention defined in the claims is not limited thereto. It will be obvious to those skilled in the art that various modifications and changes can be made within the gist. For example, the coupler 3-2 shown in FIG.
If the energy of the radio wave at the point (2) is large and the booster 2-2 need not be used, the booster 2-2 can be omitted.

[0020]

According to the present invention, laying a new guide line for transmitting a medium-frequency radio wave in a subway track or a tunnel for an automobile road, which has already been constructed, requires a large amount of cost and is complicated and difficult. Have been cited as disadvantages of the prior art. It is necessary to have a large number of security personnel, especially when working in high places at night in tunnels and traffic restrictions.
All of this returned money.
On the other hand, in the present invention, a great economic effect can be expected because the existing lines and pipes are used.

[Brief description of the drawings]

FIG. 1 is a system diagram illustrating a first embodiment according to the method of the present invention.

FIG. 2 shows a configuration example of a coupler used in the method of the present invention.

FIG. 3 is a system diagram illustrating a third embodiment according to the method of the present invention.

[Explanation of symbols]

 Reference Signs List 1,31 Medium-wave radio receiving antenna 2,33 Booster 3 Coupler 4 Existing coaxial cable 5 Booster for co-listening 6 Front-end for co-listening 7 Commercial power supply 8 High-voltage transformer 9 Earth 10 Distribution board 11 Capacitor 12 Connection point 13,34 Tunnel 14 Lighting wiring 15, 35 Lighting light 20 U-shaped ferrite core 21 Primary line 22 Secondary line 32 Feeder 36 Phase shifter 37 Level adjuster 38 Impedance matching device

Continuation of front page (72) Inventor Masaaki Kibata 2-11-10, Otemachi, Naka-ku, Hiroshima-shi, Hiroshima Japan Broadcasting Corporation Hiroshima Broadcasting Station (56) References JP-A-1-125129 (JP, A) JP-A-56-65546 (JP, A) JP-A-49-33512 (JP, A) JP-A-63-242033 (JP, A) JP-A-59-182640 (JP, A) JP-A-2-65531 (JP) JP-A-61-289737 (JP, A) JP-A-48-86316 (JP, U) JP-B-37-15154 (JP, B1) (58) Fields investigated (Int. Cl. ⁶ , DB Name) H04B 5/00 H04H 1/00 H04B 7/15 H03H 7/00

Claims (1)

(57) [Claims] 1. A receiving antenna for receiving an amplitude-modulated medium-wave radio wave is installed above a ground facility to receive the medium-wave radio wave, and the received medium-wave radio wave is received by a level adjusting means. A first booster provided with a modulated wave phase shift means and an impedance matching means, and at least two primary lines and a secondary line kept in parallel without being wound;
Via a first coupler, which is an electromagnetic coupling means sandwiched between U-shaped ferrite cores, is coupled to the existing wiring or piping of the facility and transmitted to a predetermined underground, and transmitted to the predetermined underground. The medium-wave radio wave is transmitted through a second coupler, which is electromagnetic coupling means having the same configuration as the first coupler, and a second booster provided with the same means as the first booster. Via a capacitor connected to the output of the booster, power is coupled to an existing linear wiring or pipe in the predetermined underground tunnel, and the medium-wave radio wave is re-radiated from the supplied linear wiring or pipe. A method of transmitting a medium-wave radio signal into a tunnel.