Radio frequency communication systems

• US 3,916,311 A
• Filed: 04/30/1973
• Issued: 10/28/1975
• Est. Priority Date: 05/09/1972
• Status: Expired due to Term

• Current Assignee: David James Reginald Martin, Quintin Visser Davis
• Original Assignee: David James Reginald Martin, Quintin Visser Davis
• Inventors: Martin, David James Reginald, Davis, Quintin Visser
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): Ng, Jin F.
• Application Number:
  US05/355,755
• Time in Patent Office: 911 Days
• Field of Search: 325/1,3,12,23,53,54,51,52,144,159,4,62 179/82,15AL 246/3,5,8,3D
• US Class Current: 455/14
• CPC Class Codes: H04B 5/28 using the near field of leaky cables, e.g. of leaky coaxial cables
• CPC Class Codes: H04B 5/48 Transceivers

Abstract

A radio communication system suitable for use in tunnels and mines uses a leaky radiating transmission line connected between a transmitter and a receiver to transmit radio frequency signals to a local receiver. Unidirectional repeaters are located in the transmission line and a return path is provided by a normal wire carrying demodulated signals from the receiver to the transmitter.

Claims

1. A radio frequency communication system comprising a transmitter, a receiver, a radiating transmission line having a distal end connected to the receiver and having a proximal end connected to the transmitter, a unidirectional repeater in the radiating transmission line for repeating signals in a single direction only, and a mobile station adjacent the radiating transmission line, the mobile station including a mobile receiver to receive signals radiated from the transmission line and a mobile transmitter for transmitting signals to the transmission line, and a direct link line connecting the receiver with the transmitter whereby the link line provides a return path for demodulated signals in the audio frequency range.

2. A radio frequency communication system According to claim 1, the mobile transmitter operating at a different frequency to a frequency of the said transmitter.

3. A radio frequency communication system as claimed in claim 1, and including a branch line from the said transmission line, a separate local receiver terminating the branch line and a separate link line connecting the said local receiver with the transmitter.

4. A radio frequency communication system as claimed in claim 1 and including a plurality of branch transmission lines extending from the said transmission line, a respective local receiver for terminating each of said branch transmission lines and a common link line connecting all of the local receivers with the receiver of the said transmission line.

5. A radio frequency communication system as claimed in claim 1, and including a plurality of branch transmission lines extending from the said transmission line, a respective local receiver for terminating each of said branch transmission lines and a common link line connecting all of the local receivers with the said transmitter of the system.