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System for establishing a communication link between a ground station and each of vehicle drivers within a limited communication area

  • US 4,182,989 A
  • Filed: 07/07/1978
  • Issued: 01/08/1980
  • Est. Priority Date: 10/24/1975
  • Status: Expired due to Term
First Claim
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1. A system for establishing a communication link between a vehicle driver (126) on a vehicle (116) and a base station via a plurality of peripheral units electrically connected thereto,each of said peripheral units comprising:

  • a first UHF antenna (102) which has a sharp directional characteristic, and is fixed at a support over a traffic road (103) facing the same;

    a first communication unit (112) which is connected to said first UHF antenna and includes at least one of a transmitter (124'"'"') or a receiver (138'"'"'); and

    an audio means which is connected to said first communication unit and converts a voice into a corresponding electrical audio signal when said peripheral unit comprises a transmitter, and converts an electrical audio signal into a voice when said peripheral unit comprises a receiver, and which converts a voice into a corresponding electrical signal and vise versa when said peripheral unit comprises both a transmitter and a receiver,said vehicle mounting thereon;

    a second UHF antenna (118) which has a sharp directional characteristic and directs upwards;

    a second communication unit (105) which is connected to said second UHF antenna and includes at least one of the other of a transmitter (124) or a receiver (138); and

    another audio means which is connected to said second communication unit and converts a voice into a corresponding electrical signal when said vehicle comprises a transmitter, and converts an electrical audio signal into a voice when said vehicle comprises a receiver, and which converts a voice into a corresponding electrical signal and vice versa when said vehicle comprises both a transmitter and a receiver,said transmitters including, means (132) for compressing the electrical audio signal at a predetermined ratio with respect to time, and means (136) for modulating UHF carrier by the compressed audio electrical signal, the modulated UHF signal being fed to at least one of said first and second UHF antenna in order to be radiated therefrom, andsaid receivers including, means (146) for detecting the compressed audio electrical signal from the modulated UHF signal, and means (150) for reproducing the audio electrical signal from the compressed audio electrical signal, whereby said communication link is established through one of said first UHF antenna and said second UHF antenna within a limited communication area defined by each of said first UHF antennas.

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