JP2941256B1 - Mobile signal transmission method - Google Patents

Abstract

Abstract: [PROBLEMS] Even if a transmission path in a vehicle is long, it is hardly affected by noise, and a received signal can be transmitted without deteriorating its quality. A vehicle (2) traveling on a track (1) is provided with a light receiver (3) at the rear end, receives an infrared ray (5) from a light transmitter (4) installed on the track, and receives an electric signal in a high frequency band. Convert to In addition, a signal amplifier 6 is provided near the photodetector 3 to amplify a high-frequency signal output from the photodetector 3 and to transmit the signal to the in-vehicle transmission line 7.
To the leading vehicle 2 via the. The first vehicle 2
A demodulator 8 and a monitor 9 are provided, and the high-frequency signal sent via the in-vehicle transmission line 7 is demodulated into the original low-frequency signal by the demodulator 8 and output to the monitor 9 for display. Since the noise component N generated in the in-vehicle transmission line 7 is concentrated in the low frequency band,
The signal in the high-frequency band transmitted by the in-vehicle transmission line 7 has very little influence of noise.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for receiving an optical signal transmitted from the ground by an optical space transmission system on a mobile body such as a vehicle, and installing the received signal at a remote position in the mobile body. The present invention relates to a mobile signal transmission system for transmitting data to a device.

[0002]

2. Description of the Related Art Conventionally, in a transportation system such as a railway running on a track, when a moving object, that is, a vehicle is stopped on a platform, the situation of passengers is photographed by a TV camera installed on the platform, and a video signal is transmitted. The optical signal is converted into a high frequency band optical signal, transmitted to the vehicle side, and displayed on a monitor provided in a driver's seat so that the driver can confirm safety.

When transmitting an optical signal from the ground side to the vehicle side as described above, a light transmitter is generally installed in front of or behind the traveling direction of the vehicle to transmit the optical signal, but depending on the situation around the platform, In some cases, the light transmitter can be installed only behind the vehicle. In the case where the light transmitter is installed behind the vehicle as described above, conventionally, an optical signal from the light transmitter is received by a light receiver provided at the rear end of the vehicle, converted into an electric signal, and the original low frequency is transmitted. Demodulates into a band signal,
The demodulated signal is transmitted to an output device such as a driver's seat monitor by a cable.

[0004]

However, the high frequency signal received by the photodetector is demodulated into a signal of the original low frequency band immediately in the vehicle which is a moving body as in the above-mentioned conventional art, and is transmitted to the transmission line in the vehicle. In the method of transmitting the signal with a signal in the low frequency band and passing it to an output device such as a monitor, when the light receiving device and the device receiving the signal are far apart, the transmission cable connecting the light receiving device and the device becomes long, and the vehicle There is a problem in that the signal quality is easily affected by low-frequency band noise existing at a high level inside the vehicle, and the signal quality is degraded during the transmission in the vehicle.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems. Even if a transmission path in a moving body is long, the transmission is less likely to be affected by noise, and the received signal is transmitted to an output device without degrading the quality. It is an object of the present invention to provide a mobile signal transmission method which can be obtained.

[0006]

According to the present invention, there is provided a light transmitter provided on the ground side for transmitting a modulated high-frequency band optical signal to a mobile body, and provided on the mobile body, wherein the light transmitter is provided. A light receiver that receives an optical signal transmitted from the device and converts it into an electric signal in a high frequency band, and a signal amplifier that is installed near the light receiver and amplifies a high frequency band signal output from the light receiver, A transmission line for transmitting a high-frequency band signal output from the signal amplifier to a remote position in the moving body, and a demodulator for demodulating the high-frequency band signal transmitted by the transmission line to an original low-frequency band signal And an output device installed near the demodulator and outputting a signal demodulated by the demodulator.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a system configuration diagram of a mobile signal transmission system according to an embodiment of the present invention, and FIG. 2 is a functional block diagram in the embodiment.

In FIG. 1, reference numeral 1 denotes a track on which a moving body, that is, a vehicle 2 runs. The vehicle 2 includes:
For example, a light receiver 3 is provided at the rear end, and receives an infrared ray 5 from a light transmitter 4 installed on or near the track 1 and converts it into an electric signal in a high frequency band. The light transmitter 4 is provided, for example, so as to be located behind the vehicle 2 when the vehicle 2 stops on the platform.

Also, the rearmost vehicle 2 is provided in FIG. 1 and FIG.
The signal amplifier 6 is provided near the light receiver 3 as shown in FIG. Each vehicle 2 is provided with an in-vehicle transmission path 7 made of, for example, a cable. The signal amplifier 6 amplifies the high-frequency band electric signal output from the light receiver 3 and transmits the signal to the leading vehicle 2 via the in-vehicle transmission line 7. In the leading vehicle 2, for example, an output device such as a monitor 9 is provided in front of a driver's seat, and a demodulator 8 is provided in the vicinity thereof. The demodulator 8 demodulates a high-frequency signal transmitted from the signal amplifier 6 via the in-vehicle transmission line 7 into an original low-frequency signal, and outputs the same to a monitor 9 for display.

In the above configuration, when the vehicle 2 travels on the track 1 and stops on the platform, the TV camera installed on the platform photographs the passengers of the vehicle 2,
Modulate the video signal to make it a high frequency band signal,
The light is transmitted from the light transmitter 4 to the light receiver 3 of the vehicle 2. The light receiver 3 provided at the rear end of the vehicle 2 receives the infrared ray 5 transmitted from the light transmitter 4 and converts it into an electric signal in a high frequency band. The electric signal in the high frequency band output from the light receiver 3 is amplified by a signal amplifier 6 to a sufficient level not affected by noise as shown in FIG. Is transmitted to the demodulator 8 which is being used.

FIG. 3 shows the state of the frequency distribution of the noise component N generated on the in-vehicle transmission line 7 and the high-frequency signal component S output from the signal amplifier 6. As shown in FIG. 3, the noise component N has a high level in a low frequency band, and has a very low level in a high frequency band. On the other hand, the high frequency signal component S output from the signal amplifier 6 has been amplified to a level sufficiently higher than the noise component N, and
Since the signal is transmitted in a high-frequency band having a very low noise level, the influence of noise is very small.

The demodulator 8 demodulates the high-frequency band signal transmitted from the signal amplifier 6 via the in-vehicle transmission line 7 into the original low-frequency band signal, and outputs the signal to the monitor 9 for display. . The driver of the vehicle 2 starts the vehicle 2 after confirming the safety of passengers from the image displayed on the monitor 9.

As described above, the high-frequency band signal output from the photodetector 3 is amplified by the signal amplifier 6 and demodulated to a low-frequency signal without being demodulated to the leading vehicle 2 via the in-vehicle transmission line 7.
, And demodulates the signal to the original low-frequency signal immediately before the monitor 9, so that the high-frequency signal transmitted through the in-vehicle transmission line 7 is hardly affected by noise and can maintain a very high quality. it can.

In the above embodiment, the case where the light receiver 3 is provided at the end of the vehicle 2 and the signal of the high frequency band received by the light receiver 3 is transmitted to the demodulator 8 and the monitor 9 provided in the leading vehicle. Although shown, a light receiver can be provided in the leading vehicle 2 and the high frequency band signal received by the light receiver can be transmitted to the equipment provided in the rearmost vehicle 2 in a similar manner.

In the above-described embodiment, a case has been described in which the state of the passenger on the platform is photographed by the TV camera and transmitted to the equipment mounted on the vehicle 2. However, for example, the situation of the railroad crossing is photographed by the TV camera. Running vehicle 2
For example, when transmitting to various types of transmission information.

[0016]

As described above in detail, according to the present invention, the high frequency signal received by the mobile unit is used for transmission in the mobile unit in the same high frequency band without demodulation. Since the signal is demodulated into a frequency signal and transferred to the output device, the signal is less likely to be affected by noise on the transmission line in the moving body, and the received signal can be transferred to the output device without deteriorating the signal quality.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a mobile signal transmission system according to an embodiment of the present invention.

FIG. 2 is a functional block diagram according to the embodiment;

FIG. 3 is an exemplary view showing a state of a frequency distribution of a transmission signal and noise in the embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 track 2 vehicle 3 light receiver 4 light transmitter 5 infrared ray 6 signal amplifier 7 in-car transmission line 8 demodulator 9 monitor

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04B 10/10-10/22 B61L 3/12 B61D 37/00

Claims (1)

(57) [Claims] An optical transmitter provided on the ground side for transmitting a modulated optical signal in a high-frequency band to a mobile object, and an optical signal provided on the mobile object and transmitted from the optical transmitter. A light receiver that receives light and converts it into an electric signal in a high frequency band; a signal amplifier that is installed near the light receiver and amplifies a high frequency band signal output from the light receiver; and a high frequency output from the signal amplifier A transmission path for transmitting a band signal to a remote position in the moving body; a demodulator for demodulating a high-frequency band signal transmitted by the transmission path to an original low-frequency band signal; An output device installed to output a signal demodulated by the demodulator.