Synchronization signal detector, information recording/reproducing apparatus, and synchronization signal detecting method

• US 20050213695A1
• Filed: 03/23/2005
• Published: 09/29/2005
• Est. Priority Date: 03/25/2004
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: NEC Electronics Corporation (Renesas Electronics Corporation)
• Inventors: Shin-e, Hiroyuki
• Granted Patent: US 7,676,010 B2
• Time in Patent Office: Days
• US Class Current: 375/354
• CPC Class Codes: G11B 20/10009 Improvement or modification of read or write signals
• CPC Class Codes: H04L 7/042 Detectors therefor, e.g. correlators, state machines digital correlators in general G06F17/15

Abstract

Disclosed is a synchronization signal detecting apparatus that includes a window generating circuit for generating a synchronization detecting window, a re-synchronization window generating circuit for generating a re-synchronization window, and a synchronization detecting circuit for generating a re-synchronization detecting window of a time interval that excludes a re-synchronization window mask from the re-synchronization window, detecting a synchronization signal from an input bit stream and detecting the synchronization signal in the re-synchronization detecting window. If the synchronization signal is detected in the re-synchronization detecting window without being detected in the synchronization detecting window a prescribed number of times in succession, the time interval of the re-synchronization window is updated. If the synchronization signal is detected in the re-synchronization window a prescribed number of times in succession, a re-synchronization counter outputs a re-synchronization establishment signal, the window generating circuit resets the position of the synchronization detecting window and generates the synchronization detecting window at a predetermined synchronization period, and the re-synchronization window generating circuit resets the re-synchronization window.

Claims

1. A synchronization signal detecting apparatus comprising:

a synchronization detecting circuit for detecting a synchronization signal from an input bit stream in a first window and detecting the synchronization signal from the input bit stream in a second window different from the first window; and

a control circuit;

wherein if the synchronization signal is not detected by said synchronization detecting circuit in the first window in a state in which the second window has been set to a prescribed time interval in a time range that excludes the first window, and the synchronization signal is detected by said synchronization detecting circuit in the second window a predetermined prescribed number of times in succession in accordance with a predetermined synchronization period, said control circuit exercises control for re-synchronization established to generate the first window periodically in accordance with the synchronization period using a detection position of the synchronization signal in the second window as a reference.

2. The apparatus according to claim 1, wherein said control circuit initially sets the time interval of the second window to a time interval that excludes the first window and the neighborhood thereof.

3. The apparatus according to claim 2, wherein, in a case where the synchronization signal has been detected in the second window and not in the first window, said control circuit outputs the second window, which is set to a prescribed length of time, at a position at which a succeeding synchronization signal is expected to be detected, using a detection position of the synchronization signal in the second window as a reference.

4. The apparatus according to claim 3, wherein when re-synchronization has been established, said control circuit resets the time interval of the second window to a time interval that excludes the first window and the neighborhood thereof.

5. The apparatus according to claim 1, wherein said control circuit includes:

a circuit that, in a case where the synchronization signal is not detected in the first window, is for performing control to enlarge the time interval of the first window by a predetermined prescribed width and outputting the first window of enlarged width at a position at which a succeeding synchronization signal is expected to be detected; and

a circuit for outputting a synchronization-establishment cancellation signal in a case where the synchronization signal is not detected a predetermined prescribed number of times in succession in accordance with the synchronization period in the first window.

12. An information reproducing apparatus having a synchronization signal detecting apparatus set forth in claim 1 as a synchronization signal detecting apparatus for detecting a synchronization signal from a bit signal stream that has been read out of an information recording medium.

13. An information recording/reproducing apparatus for writing information to an information recording medium and having a synchronization signal detecting apparatus set forth in claim 1 as a synchronization signal detecting apparatus for detecting a synchronization signal from a bit signal stream that has been read out of the information recording medium.

6. A synchronization signal detecting apparatus comprising:

a synchronization detecting circuit for detecting a synchronization signal from an input bit stream in a first window and detecting the synchronization signal from the input bit stream in a second window that is different from the first window;

a circuit for generating the first window;

a circuit for generating a third window;

a circuit for generating a window mask of a prescribed time interval that includes the first window;

a circuit for generating the second window comprising a time interval obtained by excluding the window mask from a time interval of the third window;

said circuit for generating the third window, when reset, setting the third window so as to extend over the entire interval of the input bit stream; and

a control circuit;

wherein if the synchronization signal has been detected by said synchronization detecting circuit in the second window and not in the first window, then said control circuit exercises control for setting the time interval of the second window to a predetermined length of time and generating the second window at a position at which a succeeding synchronization signal is expected to be detected, using a detection position of the synchronization signal in the second window as a reference; and

if synchronization has been detected a predetermined prescribed number of times in succession in the second window, then said control circuit exercises control for re-synchronization established to generate the first window in accordance with the synchronization period using a detection position of the synchronization signal in the second window as a reference.

7. The apparatus according to claim 6, wherein the circuit for generating the third window is reset when re-synchronization has been established.

8. A synchronization signal detecting apparatus comprising:

a window generating circuit for generating a synchronization detecting window that defines a first time interval for detecting synchronization, and a re-synchronization window mask of a time interval the same as the synchronization detecting window or that includes the synchronization detecting window;

a re-synchronization window generating circuit for generating a re-synchronization window that defines a second time interval;

a circuit for generating a re-synchronization detecting window comprising a time interval obtained by excluding the re-synchronization window mask from a time interval of the re-synchronization window;

a synchronization detecting circuit for detecting a synchronization signal from an input bit stream in the synchronization detecting window and detecting the synchronization signal from the input bit stream in the re-synchronization detecting window; and

a re-synchronization counter for counting synchronization detections in the re-synchronization detecting window by said synchronization detecting circuit;

wherein if the synchronization signal is detected in the re-synchronization detecting window and not in the synchronization detecting window by said synchronization detecting circuit and said re-synchronization counter counts detection of synchronization in the re-synchronization detecting window a predetermined number of times in succession, said re-synchronization counter outputs a re-synchronization establishment signal;

said window generating circuit receives the re-synchronization establishment signal and generates the synchronization detecting window in accordance with a predetermined synchronization period using a detection position of the synchronization signal in the re-synchronization detecting window as a reference; and

said re-synchronization window generating circuit, receiving the re-synchronization establishment signal, sets the re-synchronization detecting window to a normally activated state.

9. The apparatus according to claim 8, wherein, if the synchronization signal is not detected in the synchronization detecting window in a state in which synchronization has been established, then said window generating circuit enlarges the width of the synchronization detecting window in stages.

10. The apparatus according to claim 8, further comprising:

a backward protection counter for generating a synchronization establishment signal when the backward protection counter counts detection of the synchronization signal in the synchronization detecting window of said synchronization detecting circuit a prescribed number of times in succession; and

a forward protection counter for outputting a synchronization cancellation signal when the forward protection counter counts a synchronization miss in the synchronization detecting window in said synchronization detecting circuit a prescribed number of times in succession in a state of synchronization establishment.

11. The apparatus according to claim 10, wherein said backward protection counter is reset by receiving the synchronization cancellation signal from said forward protection counter and the synchronization miss in the synchronization detecting window in said synchronization detecting circuit;

and

said forward protection counter is reset by receiving detection of the synchronization signal in the synchronization detecting window of said synchronization detecting circuit and the re-synchronization establishment signal from said re-synchronization counter.

14. A method of detecting a synchronization signal in a window from an input bit stream, said method comprising:

generating first and second windows that define time intervals for detecting a synchronization signal, and setting the second window to a prescribed time interval of a time range from which the first window has been excluded; and

if the synchronization signal is detected a predetermined prescribed number of times in succession in the second window in accordance with a predetermined synchronization period without being detected in the first window, generating the first window in accordance with the synchronization period using a detection position of the synchronization signal in the second window as a reference.