RADIO COMMUNICATION TRANSMISSION SYSTEM FOR VEHICLES

• US 3,750,020 A
• Filed: 07/12/1971
• Issued: 07/31/1973
• Est. Priority Date: 08/17/1967
• Status: Expired due to Term

• Current Assignee: Kenji Shibuya, Masaaki Sasada, Mikio Nakagawa, Taichiro Nagao, Takeshi Baba
• Original Assignee: Kenji Shibuya, Masaaki Sasada, Mikio Nakagawa, Taichiro Nagao, Takeshi Baba
• Inventors: Baba, Takeshi, Shibuya, Kenji, Sasada, Masaaki, Nakagawa, Mikio, Nagao, Taichiro
• Primary Examiner(s): Griffin, Robert L.
• Assistant Examiner(s): Moore, William S.
• Application Number:
  US05/161,439
• Time in Patent Office: 750 Days
• Field of Search: 325/1,3,9,51,53,55,62,5,11,52,54
• US Class Current: 455/14
• CPC Class Codes: H04B 5/28 using the near field of leaky cables, e.g. of leaky coaxial cables

Abstract

A radio communication transmission system for moving vehicles following a track wherein an intermediate frequency communication signal is transmitted on a leaky coaxial cable at a low loss from a ground station. This signal is periodically amplified, if required, to compensate for attenuation, and is also periodically frequency converted into a radio frequency signal which is transmitted along with the aforesaid intermediate frequency signal on the same leaky coaxial cable for uniform leakage therealong for coupling to an antenna on a vehicle traveling adjacent the leaky coaxial cable. A transmitter is provided on the moving vehicle and transmits a second radio frequency signal from the vehicle to couple the signal to the leaky coaxial cable for transmission thereon. This second radio frequency signal is then frequency converted to a second intermediate frequency signal for transmission at a low loss thereafter on the same leaky coaxial cable to a ground station for reception.

Claims

1. A radio communication transmission system for moving vehicles following a track comprising a leaky coaxial cable installed in parallel along a track for a moving vehicle, repeaters interposed in said cable at predetermined locations, transmission means connected to said leaky coaxial cable to transmit thereon a signal from a ground station along said leaky coaxial cable at a low loss from repeater to repeater at a first intermediate frequency, amplification means at each repeater responsive to said first intermediate frequency signal to retransmit said first intermediate frequency signal at a low loss further along said leaky coaxial cable, a frequency converter at each repeater responsive to said first intermediate frequency signal to frequency convert a sample of said first intermediate frequency signal into a first radio frequency signal and to transmit said first radio frequency signal further along said leaky coaxial cable at a uniform leakage for coupling with a receiving antenna on a vehicle on the track, a transmitter with a transmission antenna on a vehicle on the track for the transmission of a second radio frequency signal which will couple with said leaky coaxial cable, said converter being operable to frequency convert said second radio frequency signal to a second intermediate frequency signal and to transmit said second intermediate frequency signal at a low loss on said leaky coaxial cable from repeater to repeater for eventual reception by a ground station.

2. The method of transmitting communication signals between a moving vehicle and a ground station comprising the steps of transmitting an intermediate frequency communication signal on a leaky coaxial cable at a low loss, amplifying said inteRmediate frequency signal and retransmitting said intermediate frequency signal at predetermined locations, frequency converting a sample of said signal intermediate frequency into a radio frequency signal and transmitting said radio frequency signal along with said intermediate frequency signal on the same leaky coaxial cable a said predetermined locations for uniform leakage therealong of said radio frequency signal for coupling to an antenna on a vehicle traveling adjacent to said leaky coaxial cable.

3. The method of claim 2 characterized by the steps of transmitting a second radio frequency signal from a vehicle moving adjacent the leaky coaxial cable to couple the same thereto for transmission thereon, and frequency converting said second radio frequency signal on said leaky coaxial cable to a second intermediate frequency signal for transmission at a low loss on said leaky coaxial cable to a ground station.