NOISE ERROR CORRECTING AND EXCESSIVE NOISE REJECTING SYSTEM

• US 3,701,102 A
• Filed: 05/03/1971
• Issued: 10/24/1972
• Est. Priority Date: 05/03/1971
• Status: Expired due to Term

• Current Assignee: GE Fanuc Automation North America Incorporated, General Electric Company
• Original Assignee: Gary W. Bowen, Max Berman
• Inventors: Berman, Max, Bowen, Gary W.
• Primary Examiner(s): Yusko, Donald J.
• Application Number:
  US05/139,662
• Time in Patent Office: 540 Days
• Field of Search: 340/146.1,31,32,51,168 343/6.5 325/312,323,325,41,42
• US Class Current: 377/108
• CPC Class Codes: B61L 25/043 using inductive tags
• CPC Class Codes: G08G 1/017 identifying vehicles G08G1/015, G08G1/054 take precedence

Abstract

A noise error correcting and excessive noise error rejection system for use preferably in an identification interrogation system in which a scanned or swept frequency spectrum is transmitted and certain discrete frequencies are reradiated depending upon the frequency of tuned circuits located on the object to be identified. The system uses a constant number of bits out of a larger number of bit positions for all symbols or digits used. A check for excessive noise is made by counting the number of bits per digit or symbol received on a first sweep. Excessive noise is defined as a predetermined excess of bits in a predetermined number of digits. On a second sweep, the data received on the first sweep is corrected and further checks to insure accuracy are made.

Claims

1. An excessive noise rejecting system for use in a symbol identification interrogation system which utilizes consecutive frequency swept transmitted signals and returned signals at predetermined frequencies determined by an object radiated, every identification symbol being comprised of M bits in N bit positions, wherein N is a larger number than M, comprising;

means for receiving returned signals on said consecutive frequency sweeps and converting said signals to frequency sweep signal pulses on each sweep, respectively;

means for counting the number of signal pulses in the N bit positions of each symbol;

means for generating an excessive noise signal when the count of the number of each frequency sweep signal pulses exceeds a predetermined number; and

means for rejecting the frequency sweep signal pulse data upon generation of said excessive noise signal.

2. A noise error correcting and excessive noise rejecting system as recited in claim 1 wherein said means for generating an excessive noise signal comprises:

means for generating a noise pulse whenever the count of the number of frequency sweep signal pulses in the N bit positions of a symbol exceeds a predetermined number; and

means for counting said noise pulses on each sweep and generating said excessive noise signal when the count of said noise pulses on any one of said sweeps equals a predetermined number.

3. A noise error correcting and excessive noise rejecting system for use in a symbol identification interrogation system which utilizes consecutive frequency swept transmitted signals and returned signals at predetermined frequencies determined by an object radiated, every identification symbol being comprised of M bits in N bit positions, wherein N is a larger number than M, comprising:

means for receiving returned signals on a first and a second frequency sweep and converting said signals to first frequency sweep signal pulses and second frequency sweep signal pulses, respectively;

means for counting the number of signal pulses in the N bIt positions of each symbol;

means for storing said first frequency sweep signal pulses produced on said first frequency sweep;

means for generating a noise pulse whenever the count of the number of first frequency sweep signal pulses in the N bit positions of a symbol exceeds a predetermined number;

means for counting said noise pulses on said first and second frequency sweeps and generating an excessive noise signal when the count of said noise pulses on said first or said second sweep equals a predetermined number;

means for rejecting the frequency sweep pulse data upon generation of said excessive noise signal on said first or said second frequency sweep; and

comparator means for comparing said second frequency sweep signal pulses with corresponding first frequency sweep signal pulses stored in said storage means and for cancelling a first frequency sweep signal pulse stored in said storage means upon a corresponding signal pulse being absent from said second frequency sweep.

4. A noise error correcting and excessive noise rejecting system as recited in claim 3 wherein said storage means is a recirculating storage means.

5. A noise error correcting and excessive noise rejecting system as recited in claim 4 further comprising:

counting means for counting the number of signal pulses per N bit positions of a symbol stored in said recirculating storage means; and

means for rejecting the signal pulse data stored in said recirculating storage means if said counting means contains a count other than M after sensing N bit positions of a symbol in said recirculating storage means.

6. A noise error correcting and excessive noise rejecting system as recited in claim 3 wherein said storage means is a recirculating shift register means.

7. A noise error correcting and excessive noise rejecting system as recited in claim 6 further comprising:

counting means for counting the number of signal pulses per N bit positions of a symbol stored in said recirculating shift register means; and

means for rejecting the signal pulse data stored in said recirculating shift register means if said counting means contains a count other than M after sensing N bit positions of a symbol in said recirculating shift register means.