CONCURRENT SAME-FREQUENCY FM RADIO REPEATER

• US 3,636,453 A
• Filed: 05/07/1969
• Issued: 01/18/1972
• Est. Priority Date: 05/07/1969
• Status: Expired due to Term

• Current Assignee: Quintin H. George
• Original Assignee: Quintin H. George
• Inventors: George, Quintin H.
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): Lange, Richard P.
• Application Number:
  US04/822,541
• Time in Patent Office: 986 Days
• Field of Search: 325/8,21,23,24,12,6,11,7 343/180,6.8 179/170 330/4.5 331/55,153
• US Class Current: 455/19
• CPC Class Codes: H04B 7/15528 Control of operation parameters of a relay station to exploit the physical medium

Abstract

An antenna system, used for simultaneous reception and transmission, is coupled by way of a hybrid device to an RF amplifier having less gain than the isolation loss introduced between its output and input by the hybrid. Additional gain, beyond the finite isolation of the hybrid, is provided by an oscillator which is coupled in single-port fashion to the circuit and tends to synchronize with applied signals that are substantially weaker than its output.

Claims

1. A concurrent same-frequency repeater for receiving, amplifying, and retransmitting frequency-modulated radio signals, comprising:

a. a radiofrequency hybrid having two pairs of respectively conjugate ports, b. an antenna system coupled to one of said ports, c. a matching network coupled to the port that is conjugate to the one to which said antenna is coupled, and designed to simulate the impedance of said antenna system, d. a radiofrequency amplifier having input and output terminals coupled respectively to the other conjugate pair of ports, the gain of said amplifier being less than the hybrid isolation between said last-mentioned ports, and e. an injection-locked oscillator coupled to a point in the circuit between said last-mentioned ports, said oscillator having a tendency to synchronize with radiofrequency signals at said point that are substantially weaker than the output of said oscillator.

2. The invention set forth in claim 1, wherein the path between said two parts that includes said amplifier further includes:

a. first and second mixers, b. means for coupling the output of said first mixer to the input of the second, including a band pass filter designed to pass the free running frequency of said injection locked oscillator and a band of frequencies in the vicinity thereof, c. a common local oscillator coupled to both said mixers, d. one of said mixers including means for selecting its difference frequency product as its output and the other of said second mixers including means for selecting its sum frequency product as its output, and e. means for coupling said injection-locked oscillator to a point in said circuit between said first and second mixers.

3. The invention set forth in claim 2, wherein said path between said two ports further includes a phase shifter.