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A new ground-to-train communication system using free-space optics technology

We propose a new ground-to-train communication system using free-space optics between a train and the ground. In the proposed system, a cylindrical concave lens spreads the incoming beam from transmitter (Laser Diode, LD) horizontally to form a wide fan-shaped beam. The fan-shaped beam is projected...

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Bibliographic Details
Main Authors: KOTAKE, H, MATSUZAWA, T, SHIMURA, A, HARUYAMA, S, NAKAGAWA, M
Format: Conference Proceeding
Language:English
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Summary:We propose a new ground-to-train communication system using free-space optics between a train and the ground. In the proposed system, a cylindrical concave lens spreads the incoming beam from transmitter (Laser Diode, LD) horizontally to form a wide fan-shaped beam. The fan-shaped beam is projected to a train and the width of the projected beam is equal to the length of a typical bullet-train car. This transmitter with cylindrical concave lens and a receiver (Avalanche Photo Diode, APD) are installed on a train and the ground, and the horizontally spread beam is received continuously by the corresponding receiver. The train can keep a communication link continuously to the ground thanks to this spread beam. We analyzed the performance of the proposed system by experiments. The experimental results show that a sufficient received Signal-to- Noise Ratio (SNR) can be obtained when a train is not moving; therefore, the signal can be received continuously even when the train is moving. Furthermore, in order to keep a continuous communication link even when the train vibrates or shifts vertically, the vertical spread angle of a laser beam is adjusted between 0.1 degrees and 0.5 degrees. These experimental results lead to the conclusion that this system is expected to be a Giga-bit class high speed communication technology between the train and the ground.
ISSN:1746-4498
1743-3509
DOI:10.2495/CR060671