RETRANSMISSION SYSTEM

• US 3,631,494 A
• Filed: 08/08/1969
• Issued: 12/28/1971
• Est. Priority Date: 08/08/1969
• Status: Expired due to Term

• Current Assignee: Michael J. Gans, Reudink Douglas O J
• Original Assignee: Michael J. Gans, Reudink Douglas O J
• Inventors: Gans, Michael J., REUDINK DOUGLAS O J
• Application Number:
  US04/848,582
• Time in Patent Office: 872 Days
• US Class Current: 342/367
• CPC Class Codes: H04B 7/04 using two or more spaced independent antennas

Abstract

In a space diversity phased array radio station capable of retransmission, each branch receives a pilot signal containing phase information which is used to continuously control the phase of the retransmitted signal containing return intelligence, thus providing adaptive retransmission from the array. To prevent a strong retransmission signal from swamping a weak pilot when their frequency separation is small, a sample of the retransmission is applied to the receiving section to act as the local oscillator for down-conversion of the pilot, thereby avoiding unwanted mixer products in the retransmission loop and minimizing crosstalk between the reception and retransmission.

Claims

1. A radio communication system for transmitting between an originating station and retransmitting station comprising means for transmitting from said originating station a phase reference signal, an antenna array of elements located at said retransmitting station, each of said elements receiving said phase reference signal having a phase angle distinctive to that element and each element having associated therewith a retransmission branch including:

means for combining a sample of a retransmitted signal with said received phase reference signal to produce a control signal, means for utilizing said control signal to operate on a generated return signal to produce said retransmitted signal having a phase angle opposite that of said distinctive angle of said each element, and means for radiating from said each element said retransmitted signal.

2. A system as claimed in claim 1 wherein means are provided for generating said return signal so as to produce said generated signal having a frequency such that the frequency of said retransmitted signal is within the phase coherent bandwidth of said phase reference signal.

3. A system as claimed in claim 2 wherein said means for combining said sample of retransmitted signal and said received phase reference signal includes a path for passing leakage of said retransmitted signal to a mixer where said leakage is mixed with said received phase reference signal.

4. A system as claimed in claim 2 wherein at least one of said stations is a mobile station.

5. A system as claimed in claim 2 wherein means are provided for modulating an intelligence signal on said generated signal.

6. A system as claimed in claim 2 wherein means are provided for transmitting intelligence modulation from said originating station in association with said phase reference signal and said retransmitting station includes means for receiving said intelligence modulation in each of said branches, means for reducing to a common phase the reception in each of said branches and means for combining and detecting said received modulation exclusive of all other modulation.

7. A system as claimed in claim 2 wherein said combining means for producing a control signal in each of said retransmission branches includes means for mixing said phase reference signal and said sample of said retransmitted signal to produce an intermediary signal and means for eliminating from said intermediary signal the effect of said opposite phase angle present on said retransmitted signal.

8. A system as claimed in claim 2 wherein said combining means for producing a control signal in each of said retransmitting branches includes means for mixing said phase reference signal and said sample of said retransmitted signal to produce an intermediary signal and means for dividing by two the frequency and phase of said intermediary signal to produce said control signal, whereby said control signal has eliminated therefrom the effect of said opposite phase angle present on said retransmitted signal.

9. A system as claimed in claim 8 further comprising in each of said retransmission branches means for mixing with said intermediary signal an offset oscillator signal of constant frequency and constant phase common to all of said branches.

10. A system as claimed in claim 2 wherein said combining means for producing a control signal in each of said retransmission branches includes means for mixing said phase reference signal and said sample of said retransmitted signal to produce an intermediary signal, means for mixing said sample of said retransmitted signal with an oscillator signal of constant frequency and constant phase common to all of said branches to produce a difference output, means for mixing said intermediary signal with said difference output to produce said control signal Having a phase angle proportional to said distinctive phase angle of said phase reference signal received by said each element and unaffected by the phase of said retransmitted signal, and wherein said means for utilizing said control signal to operate on said generated signal further includes means for mixing said generated signal and said control signal to produce a resultant signal and means for mixing said resultant signal with said oscillator signal to produce said retransmitted signal.

11. A system as claimed in claim 10 wherein the center frequency of said generated return signal is selected such that a frequency offset of said resultant signal is produced.

12. A radio retransmitting station comprising a transmitter and a plurality of branches each of said branches comprising antenna means for receiving a pilot signal and for radiating a transmitted signal, means for operating on said received pilot signal to produce a control signal having a phase angle proportional to the phase of said pilot signal said operating means including means for beating said pilot and a sample of said transmitted signal, and means for combining said control signal with the signal from said transmitter to produce said transmitted signal having a conjugate phase to that of said pilot signal received by said antenna.