COMMUNICATIONS SYSTEM HAVING SINGLE RF CHANNEL DIVERSITY MEANS

• US 3,842,352 A
• Filed: 07/14/1972
• Issued: 10/15/1974
• Est. Priority Date: 07/14/1972
• Status: Expired due to Term

• Current Assignee: Walter E. Cote
• Original Assignee: Walter E. Cote
• Inventors: Cote, Walter E.
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): Ng, Jin F.
• Application Number:
  US05/271,944
• Time in Patent Office: 823 Days
• Field of Search: 325/40,56,59,65 343/200 179/15R,15FD,15FS
• US Class Current: 455/504
• CPC Class Codes: H04B 7/02 Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas RAKE receivers H04B1/7115
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence

Abstract

Time diversity utilizing a single RF channel is achieved by duplicating the information bearing signal to be transmitted, delaying one duplicate signal, multiplexing the delayed and undelayed signals on an RF carrier and transmitting the multiplexed signal to a remote receiving station. At the receiving station the received signal is demultiplexed and the undelayed duplicate signal is delayed to bring it into time coincidence with the delayed duplicate signal. Subsequent combining of these signals provides a signal that is not subject to information loss due to fade or other interference for periods equal to or less than the delay time. A third delayed duplicate signal is also comprehended that obviates the effects of short and intermittent recovery time. In the preferred embodiment analog signals are transmitted by apparatus utilizing audio frequency delay lines and frequency division multiplexers and demultiplexers.

Claims

1. A communications system comprising at a transmitting station;

a signal source, first, second and third transmission lines, each said transmission line being connected to receive simultaneously signals generated by said signal source, a first time delay means disposed in said second transmission line, a second time delay means disposed in said third transmission line, a multiplexer adapted to multiplex the signals on each transmission line onto a signal RF carrier; and

a communications transmitter connected to the output thereof for transmitting said multiplexed signals to a remote receiving station, and at said remote receiving station, a communications receiver adapted to receive said transmitted multiplexed signals, a demultiplexer connected thereto, a fourth transmission line connected to the output of said demultiplexer to receive undelayed demultiplexed signals, fifth and sixth transmission lines connected to the output of said demultiplexer to receive delayed demultiplexed signals, a third time delay means disposed in said fourth transmission line, means for combining the signals on said fourth and fifth transmission lines, a seventh transmission line connEcted to receive the combined signals of said fourth and fifth transmission lines, a fourth time delay means disposed in said seventh transmission line, said third and fourth time delay means being adapted to bring the demultiplexed signals on said fourth, fifth and sixth transmission line into time coincidence, and means for combining the signals on said sixth and seventh transmission lines.

2. A communications system as defined in claim 1 wherein said signal source generates information bearing analog signals.

3. A communications system as defined in claim 2 wherein said multiplexer is a frequency division multiplexer and said demultiplexer is a frequency division demultiplexer.

4. A communications system as defined in claim 3 wherein said first, second, third and fourth time delay means are audio frequency delay lines.

5. A communications system as defined in claim 4 wherein said first and third time delay means are audio frequency delay lines having delay times in the region of 5 milliseconds, said second delay means is an audio frequency delay line having a delay time in the region of 100 milliseconds and said fourth time delay means is an audio frequency delay line having a delay time in the region of 95 milliseconds.