Data recognition apparatus

• US 4,227,175 A
• Filed: 01/15/1979
• Issued: 10/07/1980
• Est. Priority Date: 01/18/1978
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Newman, Eric L.
• Primary Examiner(s): Atkinson, Charles E.
• Application Number:
  US06/003,551
• Time in Patent Office: 631 Days
• Field of Search: 340/146.1 R, 340/146.2, 340/146.3 WD, 364/728, 364/821, 364/862, 325/42, 325/323, 371/31, 371/69
• US Class Current: 340/146.2
• CPC Class Codes: G11B 20/1423 Code representation depending on subsequent bits, e.g. delay modulation, double density code, Miller code
• CPC Class Codes: G11B 20/1426 conversion to or from block codes or representations thereof
• CPC Class Codes: H04L 25/068 by sampling faster than the nominal bit rate

Abstract

Data recognition apparatus includes a temporary storage to hold three data bits, a readable storage to store eight different sequences which are expected to occur, and a comparison means to find the closest match of the contents of the temporary storage with the readable storage at each bit time. Error detection and error correction are realized as each bit is recognized three times sequentially. The apparatus may use surface acoustic wave and charge coupled device filter banks, and analog to digital conversion plus data processor comparison.

Claims

1. Data recognition apparatus responsive to a serial input waveform, the input waveform including N different possible overlaping waveform sequences, each waveform sequence representing a plurality of m binary data bits, and having a period of m equal, or substantially equal bit times comprising:

temporary storage means for storing the input waveform and having sufficient capacity to temporarily store any one of said waveform sequences;

readable storage means for storing representations of N different waveform sequences expected to occur in the input waveform; and

comparison means operable during each bit time for comparing the contents of said temporary storage means with the contents of said readable storage means and for indicating the closest match between each input waveform sequence and said expected waveform sequences.

2. Apparatus as in claim 1, including means coupled to receive said input waveform and to the input circuit of said temporary storage means for sampling the input waveform K times during each bit time, said comparison means being operable upon K×

m samples during each bit time.

3. Apparatus as in claim 1, including clock means coupled to receive said input waveform for providing bit timing from said input waveform.

4. Apparatus as in claim 1, wherein said temporary storage means and readable storage means comprise 2^m delay devices in parallel.

5. Apparatus as in claim 4, wherein said delay devices comprise surface acoustic wave devices.

6. Apparatus as in claim 4, wherein said delay devices comprise charge coupled devices.

7. Apparatus as in claim 1, wherein said temporary storage means comprises a shift register, said readable storage means comprises a digital store, and said comparison means comprises a digital data processor.

8. Apparatus as in claim 1, including logic means coupled to the output circuit of said comparison means for detecting at each bit time when other than only one expected waveform sequence is indicated, and for providing an error signal.

9. Apparatus as in claim 8, wherein said logic means comprises error detection means for detecting when the same individual bit does not occur in each of m successive overlapping input waveform sequences recognized by said comparison means, and for providing an error signal.

10. Apparatus as in claim 8, wherein said logic means comprises error correction means for operating upon the recognized bits of m successive overlapping input sequences processed by said comparison means to provide error correction.

11. A method of recognizing data, the data being represented by a serial input waveform including N different possible overlapping waveform sequences, each waveform sequence representing a plurality of m binary bits, and having a period of m equal, or substantially equal bit times, comprising the steps of:

temporarily storing the input waveform in temporary storage means having sufficient capacity to store any one of said waveform sequences;

storing in readable storage means representations of N different waveform sequences expected to occur in the input waveform;

comparing during each bit time the contents of said temporary storage means with the contents of said readable storage means and indicating the closest match between each input waveform sequence and said expected waveform sequences.

12. A method as in claim 11, including the steps of sampling the input waveform K times during each bit time, and comparing K×

m samples during each bit time.

13. A method as in claim 11, comprising the steps of extracting bit timing from said input waveform.

14. A method as in claim 11, wherein said step of temporarily storing comprises storing in 2^m delay devices in parallel.