Spread spectrum signal estimator

• US 4,361,891 A
• Filed: 12/22/1980
• Issued: 11/30/1982
• Est. Priority Date: 12/22/1980
• Status: Expired due to Fees

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: General Electric Company
• Inventors: Quick, Marshall K., Lobenstein, Helmut
• Primary Examiner(s): Safourek, Benedict V.
• Assistant Examiner(s): Chin, Stephen
• Application Number:
  US06/218,899
• Time in Patent Office: 708 Days
• Field of Search: 375/1, 375/34, 375/94, 375/58, 375/115, 370/93, 370/107, 343/100 SA, 343/100 LE, 343/100 CL, 343/5 PN, 455/276, 455/278
• US Class Current: 375/142
• CPC Class Codes: H01Q 3/2617 Array of identical elements
• CPC Class Codes: H04B 1/69 Spread spectrum techniques

Abstract

A PN sequence signal estimator is described which synergistically co-operates with an adaptive array processor and a spread spectrum communication system modem such that the adaptive array will null interfering signals, but not desired signals. This is accomplished with the signal estimator generating an estimate of the desired coded signal through the use of the local code and the detected correlation in the modem, and feeding the estimate back to the array in such a manner that it subtracts from the array error voltage, thereby inhibiting null formation.

Claims

1. A signal estimator utilizing an array output signal applied to the input of a communication modem and produced from an adaptive array processor in response to a received pseudo noise communication signal, and a detection gate signal and a polarity modulation signal from the communication modem in order to generate a signal estimate of a desired signal, said signal estimator comprising:

(a) a channel assignment means receiving said detection gate signal and allocating said signal to one of its N output channels;

(b) a local code storage means containing a unique pseudo random noise (PN) code designated by the communication modem;

(c) a plurality of read/write means, each of said read/write means having an input terminal and an output terminal, said input terminal being connected to one of said N output channels of said channel assignment means, said read/write means being able to read a pseudo random noise (PN) code from said local code storage means;

(d) a gating means receiving said pseudo random noise (PN) code from said read/write means and weighting said code with said polarity modulation signal from the communication modem to yield a pilot signal; and

(e) a subtraction means calculating a residue signal by subtracting said pilot signal from said array output signal.

2. The signal estimator as claimed in claim 1, further including a one chip delay element and a summing element, said delay element delaying said pilot signal by at least one chip time and said summing element calculating the sum of said pilot signal and said pilot signal delayed by at least one chip time, said sum being a modified pilot signal.

3. The signal estimator as claimed in claim 2, further including an adjustable delay means in order to delay said modified pilot signal before it reaches said subtractor means.

4. A signal estimator utilizing an array output signal applied to the input of a communication modem and produced from an adaptive array processor in response to a received pseudo noise communication signal, and N detection gate signals and N polarity modulation signals from the communication modem in order to generate a signal estimate of N desired signals, said signal estimator comprising:

(a) a channel assignment means receiving one of said detection gate signals and allocating said signal to one of its N output channels;

(b) N local code storage means containing a pseudo random noise (PN) code designated by the communication modem;

(c) N read/write means, each of said read/write means having an input terminal and an output terminal, said input terminal being connected to one of said N output channels of said channel assignment means, each of said read/write means being able to read a pseudo noise (PN) code from said local code storage means, each of said read/write means being able to output a PN code corresponding to that portion of a PN code that is known apriori to follow a PN code that had been correlated in the modem to cause said detection gate signal to have been generated;

(d) a gating means receiving at least one pseudo random noise (PN) code from at least one of said read/write means and weighting said code with said polarity modulation signal that corresponds to said detection gate signal from the communication modem, said gating means containing a summing means that yields a pilot signal by combining all pseudo random noise (PN) codes after they have each been separately weighted by said polarity modulation signals; and

(e) a subtraction means calculating a residue signal by subtracting said pilot signal from said array output signal.

5. The signal estimator as claimed in claim 4, further including a one chip delay element and a summing element, said delay element delaying said pilot signal by at least one chip time and said summing element calculating the sum of said pilot signal and said pilot signal delayed by at least one chip time, said sum being a modified pilot signal.

6. The signal estimator as claimed in claim 5, further including an adjustable delay means in order to delay said modified pilot signal before it reaches said subtractor means.