Time division multiple access communications system

• US 3,908,088 A
• Filed: 05/22/1974
• Issued: 09/23/1975
• Est. Priority Date: 05/22/1974
• Status: Expired due to Term

• Current Assignee: Frank S. Gutleber
• Original Assignee: Frank S. Gutleber
• Inventors: Gutleber, Frank S.
• Primary Examiner(s): Blakeslee, Ralph D.
• Application Number:
  US05/472,320
• Time in Patent Office: 489 Days
• Field of Search: 179/15BS,15AP,15BC 340/348 343/17.1 325/42
• US Class Current: 370/347
• CPC Class Codes: H04B 7/216 Code division or spread-spectrum multiple access [CDMA, SSMA]
• CPC Class Codes: H04J 13/10 Code generation

Abstract

A time division multiple access communications system employing perfect noise codes to enable utilization of the system. The noise codes employed are of the type termed code mates having correlation functions which upon detection provide an impulse autocorrelation function. Improvements in signal-to-noise power ratio and in signal-to-jamming power ratio will be seen to result, as contrasted with similar communications systems operating with comparable peak powers but without coding.

Claims

1. In a multiple access communications system, the combination therewith of:

first means for generating a pair of coded signals;

second means for generating a timing reference signal; and

third means for multiplexing said coded signals with said timing reference signal for communication of said coded signals to users accessing said system at predetermined assigned intervals of time; and

wherein said first-mentioned means generates a pair of coded signals which upon receipt and detection by a user accessing the system produces an output signal having an impulse autocorrelation function during his assigned, predetermined interval of time within said timing reference signal.

2. The combination of claim 1 wherein said first-mentioned means generates first and second sequences of coded pulses, the pulses of which have predetermined code patterns, different one from another, but related thereto in that upon receipt and detection, the autocorrelation function of each code will be of substantially equal magnitude and opposite polarity, or zero, for all intervals of time, other than during said assigned, predetermined interval.

3. The combination of claim 1 wherein said first means includes a plurality of code generators, one for each of said pair of coded signals, wherein said second means includes a synchronizing signal generator, and wherein said third means includes a multiplexer coupled to said code and synchronizing signal generators, a transmitter coupled to said multiplexer, a receiver coupled to said transmitter, a demultiplexer coupled to said receiver, and an autocorrelation detector coupled to said demultiplexer to provide said output signal.

4. The combination of claim 3 wherein said autocorrelation detector includes a pair of adder circuits, a plurality of time delay circuits for successively delaying the application of received coded pulses to input terminals of said adders by one interval of time each, and a plurality of phase control circuits for reversing the polarities of selected code pulses applied at said input terminals in accordance with the predetermined code patterns of said coded pulses.

5. The combination of claim 4 wherein sequential ones of said phase control circuits provide a phase reversal of 0* or 180* in inverse relationship to the sequence of coded pulses provided by said first-mentioned means.