Dsp-based data recovery

• US 20070064847A1
• Filed: 04/27/2004
• Published: 03/22/2007
• Est. Priority Date: 05/16/2003
• Status: Active Grant

• Current Assignee: Thomson Licensing (Vantiva SA)
• Original Assignee: Thomson Licensing (Vantiva SA)
• Inventors: Kochale, Axel, Gaedke, Klaus, Timmermann, Friedrich, Schaefer, Ralf-Detlef, Kabutz, Marten, Schutze, Herbert
• Granted Patent: US 7,656,982 B2
• Time in Patent Office: Days
• US Class Current: 375/355
• CPC Class Codes: G11B 20/10425 by counting out-of-lock events of a PLL
• CPC Class Codes: G11B 20/16 using non self-clocking codes, i.e. the clock signals are either recorded in a separate clocking track or in a combination of several information tracks
• CPC Class Codes: G11B 2220/2545 CDs
• CPC Class Codes: G11B 2220/2562 DVDs [digital versatile discs]; Digital video discs; MMCDs; HDCDs
• CPC Class Codes: G11B 27/3027 used signal is digitally coded

Abstract

A bit clock recovery apparatus for digital storage readout employing sync frames, where an oversampled readout signal is stored in memory, sync patterns are located in the signal using DSP means, distances of consecutive sync pattern locations are calculated, and bit clock is recovered from these distances and the knowledge about the data framing structure.

Claims

1. A method for data recovery from a time-continuous signal compliant to one or more digital signal formats each having a specific channel bit clock and a sync pattern occurring in regular intervals, the method being comprising the following steps:

sampling the time-continuous signal at a frequency at least as high as the maximum of all frequencies of the channel bit clocks of the digital signal formats;

analysing the sampled signal to locate occurrences of one or more of the sync patterns, thereby making available, as an analysis information, where in the sampled signal which ones of the sync patterns are located;

calculating from the analysis information a distance information about the distance between consecutive locations of sync patterns;

recognising, from the analysis information and the distance information, the signal format to which the signal complies,

converting the sampled signal into a converted signal which represents the data at the channel bit clock.

2. The method of claim 1, where the step of converting includes the following steps:

calculating from the analysis information and/or the distance information a channel bit rate and/or the channel bit clock, and

converting the sampled signal to the sampling rate defined by the calculated channel bit rate or bit clock.

3. The method of claim 1, additionally including the following step:

after analysing the sampled signal, providing for further use as frame alignment information the locations where sync patterns have been located.

4. The method of claim 2, additionally including the following step:

after locating a sync pattern occurrence, decoding from a second signal an address information contained therein,

6. The method of claim 1, where the step of analysing employs a cross-correlation.

7. The method of claim 1, additionally including any one or more of the following steps:

analysing after recognizing the format to which the signal complies, with an algorithm that depends on the recognized format, the sampled signal to locate occurrences of one or more predefined sync patterns, thereby making available analysis information about where in the sampled signal which ones of the sync patterns are located;

calculating with an algorithm that depends on the recognized format, from the analysis information a distance information about the distance between consecutive locations of sync patterns;

calculating with an algorithm that depends on the recognized format, from the analysis information and/or the distance information a channel bit rate and/or the channel bit clock;

converting, with an algorithm that depends on the recognized format, the sampled signal to the sampling rate defined by the calculated channel bit rate or bit clock.

8. The method of claim 4, where the sampled signal or a sample rate converted sampled signal is used as the second signal.

9. The method of claim 4, where a maximum likelihood decoder is applied for the decoding step.

10. The method of claim, 1 where the analysing (25, 310, 45) step involves the following sub-steps

a) setting as a current sync pattern a first sync pattern from a finite set of different sync patterns,

b) analysing the sampled signal to find positions of the current sync pattern,

c) if no positions are being found and the last sync pattern in the set has not been reached, setting as the current sync pattern the next sync pattern from the set and looping back to sub-step b).

11. The method of claim 10, where the analysing sub-step b) involves the following sub-steps

b1) setting as a current sync pattern version a first stretched version from a finite set of differently stretched versions of the current sync pattern,

b2) analysing the sampled signal to find positions of the current sync pattern version,

b3) if no positions are being found and the last current sync pattern version has not been reached, setting as the current sync pattern version the next sync pattern version from the set and looping back to sub-step b2).

16. The method of claim 1, where the time-continuous signal is a readout signal from a digital storage medium.

17. The method of claim 1, where the time-continuous signal is a received signal from a digital transmission.

5. (canceled)

12. An apparatus for recovering a channel bit clock from a time-continuous signal compliant to one or more digital signal formats each having a specific channel bit clock and a specific framing structure including a sync pattern occurring in regular intervals, the apparatus including

sampling means which generate a sampled signal from the time-continuous signal,

analogue to digital conversion means connected to the sampling means and

sample rate conversion means;

the apparatus comprised

an analyser adapted to analyse the sampled signal to locate occurrences of one or more of the sync patterns,

a calculator adapted to calculate a channel bit rate and/or the channel bit clock from the locations where sync patterns are located, and

a format recogniser adapted to recognise, from the analysis information and the distance information, the signal format to which the signal complies,

wherein the sample rate conversion means convert its input data to output data obeying an output sample rate equal to the channel bit rate or bit clock as calculated by the calculator.

13. The apparatus of claim 12, where the sample rate conversion means includes two or more units working in parallel, each consisting of a storage means and an associated interpolation means.

14. The apparatus of claim 12, additionally including a sync ID decoder triggered by the analyser having located a sync pattern occurrence, the sync ID decoder decoding the sync IDs from the sample rate converted digitised signal.

15. The apparatus of claim 12, where the analyser includes a sync pattern selector for selecting as current sync pattern one sync pattern from a finite set of different sync patterns and a loop back controller for looping back to an analysing step whenever for a certain current sync pattern no occurrences have been found.