JP2971795B2 - Spatial transmission equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a space transmission apparatus for transmitting information such as video from the ground to a moving train or the like.

[0002]

2. Description of the Related Art An optical space transmission device is used to transmit information such as video from the ground to a train or the like. In the optical space transmission device, an optical signal including information such as an image from a transmitter installed on the ground is received by a light receiver on the train through a front glass behind the traveling direction of the moving train. The signal received by the light receiver is transmitted to a driver's cab provided in front of the train via a coaxial cable, and is used for image display on a display device (monitor).

[0003]

As described above, in the conventional optical space transmission apparatus, a signal from a light transmitter installed on the ground is received by a light receiver installed rearward in the traveling direction of the train. The signal is transmitted to the cab in front of the train via a coaxial cable.

[0004] When the train travels in one direction, the above-described configuration allows the signal from the ground light transmitter to be received, but at a turnaround station or the like, the train travels in the opposite direction. The signal may not be received.

[0005] Whichever direction the train travels,
In order to receive a signal from a light transmitter installed on the ground, two systems of the same configuration must be installed on the train. In this case, a coaxial cable for transmitting a signal received on one side of the train to the other side and a coaxial cable for transmitting a signal in the opposite direction are required.

That is, the conventional optical space transmission apparatus can receive an optical signal from the ground only from one side of the train, and can receive optical signals from both directions of the train. It was necessary, and it was necessary to lay two coaxial cables for signal transmission on the train.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a method of receiving information from the ground in both the up and down directions of a train and providing information without providing a plurality of routes on the train. It is an object of the present invention to provide a spatial transmission device capable of performing the following.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a space transmission apparatus for receiving a signal from a ground device behind a traveling direction of a moving train and transmitting the signal to a front side of the train to provide information. One coaxial cable for transmitting a signal in the front-rear direction of the train, and a first transmission means for transmitting a signal received at a frequency f1 via the coaxial cable at a rearward position in one traveling direction; The signal received backward with respect to the other traveling direction is referred to as the frequency f
And a second transmission means for converting the signal into a signal having a frequency f2 which does not affect the signal No. 1 and transmitting the signal via the coaxial cable.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the free-space optical transmission apparatus according to the present embodiment. Here, a case where video information is transmitted to the train 2 from the ground will be described as an example. As shown in FIG. 1, it is configured by equipment installed on the ground (hereinafter referred to as ground equipment) and equipment installed in the train 2 (hereinafter referred to as on-board equipment).

The ground device is for transmitting information such as images to the train 2. In FIG. 1, the ground device transmits a signal to the rear of the train 2 when the train 2 is traveling in the downward direction. One device and a second device that transmits a signal to the rear of the train 2 when the train 2 is traveling in the upward direction are provided. When transmitting the image information, the ground devices (the first device and the second device) modulate the image signal, convert the image signal into a high-frequency signal, and spatially transmit the optical signal to the train 2 as a light transmitter. 10 and 12 are provided. In FIG. 1, a light transmitter 10 for the first device and a light transmitter 12 for the second device
Only one is shown.

The on-board device is for receiving the optical signal transmitted from the ground device and providing information to a driver or the like at the cab of the train 2. As shown in FIG.
A light receiver 30, a demodulator 32, a monitor 34, and a down-converter 36 are provided on one side (for example, a cab for the up direction) of the train 2, and a light receiver 30 is provided on the other side (for example, a cab for the down direction). A device 40, a demodulator 42, a monitor 44, and an up-converter 46 are provided. One side and the other side are connected by one coaxial cable 50.

The light receiver 30 receives an optical signal transmitted from the transmitter 10 of the ground equipment installed on the ground and converts it into a high-frequency signal. The light receiver 30 is connected to a demodulator 42 via a coaxial cable 50. ing.

The demodulator 32 demodulates a high-frequency signal into an original signal (here, a video signal). The demodulator 32 receives a high-frequency signal from a down-converter 36 and outputs a demodulated video signal to a monitor 34. .

The monitor 34 is a display device for displaying an image based on the image signal and providing information to a driver or the like at the driver's cab, and receives the image signal from the demodulator 32. The down-converter 36 converts an input high-frequency signal (a signal converted to a high frequency by the up-converter 46) into a high-frequency signal of an original frequency as originally expected.
The signal input from the coaxial cable 50 is converted and output to the demodulator 32.

The light receiver 40 receives an optical signal transmitted from the light transmitter 12 of the ground equipment installed on the ground and converts it into a high-frequency signal, and is connected to the up-converter 46.

The demodulator 42 demodulates the high-frequency signal into an original signal (video signal). The demodulator 42 receives the high-frequency signal via the coaxial cable 50 and outputs the demodulated video signal to the monitor 44. .

The monitor 44 is a display device that displays an image based on the image signal and provides information to a driver or the like at the driver's cab, and receives the image signal from the demodulator 42. The up-converter 46 converts the input high-frequency signal into a high-frequency signal of a predetermined frequency, converts the signal input from the light receiver 40, and outputs the converted signal to the down-converter 36 via the coaxial cable 50.

The coaxial cable 50 is for transmitting a high-frequency signal on the train 2 in the front-rear direction of the train 2 (for example, between the front and rear cabs).
And the up converter 46 (light receiver 40) and the down converter 36 (demodulator 32) are connected by one path.

In the present embodiment, the light receiver 30, the coaxial cable 50, and the demodulator 42 form a first transmission path,
Light receiver 40, up converter 46, coaxial cable 5
0, the down-converter 36, and the demodulator 32 constitute a second transmission path.

Next, the operation of the free-space optical transmission apparatus according to the present embodiment will be described. Normally, when the train 2 is traveling in one direction, for example, assuming that the train 2 is traveling in the downward direction, the signal is transmitted from the transmitter 10 of the ground device installed at a position behind the train 2. The received optical signal is received by a light receiver 30 installed on the rear side of the train 2, converted into a high-frequency signal, and transmitted to a demodulator 42 installed ahead through a coaxial cable 50.

The demodulator 42 demodulates the high-frequency signal input via the coaxial cable 50 into a video signal,
4 is output. The monitor 44 projects an image according to the image signal and provides the image to, for example, a driver at a driver's cab.

When the train 2 performs both departures at, for example, a return station, that is, when the train 2 travels in both the upward direction and the downward direction, the train 2 As shown in FIG. 1, ground devices are installed. Optical signals are transmitted from the transmitters 10 and 12 of the ground devices installed on both sides of the train 2.

For example, the ground equipment (first equipment) includes the light transmitter 1
The video signal V1 is modulated by 0, converted into a high-frequency signal of frequency f1, and transmitted as an optical signal. The photodetector 30 installed on the downstream side of the train 2 receives the optical signal, converts the optical signal into a high-frequency signal of the frequency f1, and demodulates the demodulator 42 installed on the downstream side via the coaxial cable 50.
To send to.

The demodulator 42 demodulates a high-frequency signal of the frequency f1 into a video signal V1 and outputs it to the monitor 44. The monitor 44 displays an image on the driver's cab on the forward side in the downward direction according to the image signal V1.

On the other hand, the ground equipment (second equipment) is
2, the video signal V2 is modulated, converted to a high-frequency signal of frequency f1, and transmitted. The optical receiver 40 installed on the rear side of the train 2 in the upward direction receives the optical signal, converts the optical signal into a high-frequency signal having the frequency f1, and outputs the high-frequency signal to the up-converter 46.

The up-converter 46 converts the high-frequency signal of the frequency f1 to a frequency that does not affect the frequency f1,
That is, the signal is converted into a high-frequency signal of a sufficiently high frequency f2 that does not cause interference even if the same transmission path is used, and
The signal is transmitted to the down converter 36 installed in the upstream in the upward direction through the line 0.

The down converter 36 converts the high frequency signal of the frequency f2 into the original high frequency signal of the frequency f1 and outputs the same to the demodulator 32. The demodulator 32 demodulates the high-frequency signal of the frequency f1 into a video signal V2 and outputs it to the monitor 34.

The monitor 44 displays an image on the driver's cab on the front side in the upward direction according to the image signal V2. In this way, the optical signal received by the downstream photodetector 30 is converted into a high-frequency signal of the frequency f1 and transmitted by the coaxial cable 50, and the optical signal received by the upstream photodetector 40 is converted by the up-converter 46. Is converted into a high-frequency signal of a sufficiently high frequency f2 which does not affect the high-frequency signal of the frequency f1 and transmitted by the coaxial cable 50. Therefore, only one coaxial cable 50 is laid on the train 2 and Information such as images can be provided at the leading cab of the train 2 based on the signals received in both directions.

The frequency f2 is calculated by the up-converter 46.
Is converted into the high-frequency signal of the original frequency f1, so that the demodulator 32 and the monitor 34 can be the same as the demodulator 42 and the monitor 44, respectively.

In the above-described embodiment, after the high-frequency signal is transmitted to the coaxial cable 50 by raising the frequency to the frequency f2 by the up-converter 46, the frequency is reduced to the frequency f1 by the down-converter 36. It is also possible to increase the frequency after transmitting the coaxial cable 50 at a frequency that does not affect the frequency of the signal.

[0031]

As described above in detail, according to the present invention, one coaxial cable laid on a train transmits signals bidirectionally at different frequencies that do not affect each other.
It is possible to receive signals from the ground and provide information in both the up and down directions of the train without providing a plurality of routes on the train.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an optical free space transmission apparatus according to an embodiment of the present invention.

[Explanation of symbols]

 10, 12 ... Light transmitter 30, 40 ... Light receiver 32, 42 ... Demodulator 34, 44 ... Monitor 36 ... Down converter 46 ... Up converter 50 ... Coaxial cable

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ identification symbol FI H04B 10/22 (58) Fields investigated (Int.Cl. ⁶ , DB name) H04B 1/76-3/44 H04B 3/50 -3/60 H04B 7/005-7/015 H04B 9/00

Claims (1)

(57) [Claims] 1. A spatial transmission device that receives a signal from a ground device behind a traveling direction of a moving train and transmits the signal to a front side of the train to provide information. One coaxial cable for transmitting a signal, a first transmission means for transmitting a signal received in the rear of one traveling direction through the coaxial cable at a frequency f1, and a rear of the other traveling direction. 2. A spatial transmission apparatus, comprising: a second transmission unit that converts a signal received in step (2) into a signal having a frequency f2 that does not affect the frequency f1 and transmits the signal via the coaxial cable.