摘要:
Tracking system for guiding an optical beam on tracks on an optical disc, said tracking system comprising a photodetector (A1, A2) for detecting optical beams derived from said optical beam, said photodetector generating a first output signal (A) and a second output signal (B), said tracking system comprising first processing means for generating a first differential signal (PP(DC)) corresponding to the low-frequency part of a difference between said first and second output signals. The tracking system comprises second processing means for generating a tracking error signal (PP(AC/DC)) defined by the addition of said first differential signal (PP(DC)) to a second differential signal (PP′(AC)), said second differential signal corresponding to a fraction of the difference in amplitude of the high-frequency components of said first and second output signals. Use: Optical disc player/writer.
摘要:
Tracking system for guiding an optical beam on tracks on an optical disc, said tracking system comprising a photodetector (A1, A2) for detecting optical beams derived from said optical beam, said photodetector generating a first output signal (A) and a second output signal (B), said tracking system comprising first processing means for generating a first differential signal (PP(DC)) corresponding to the low-frequency part of a difference between said first and second output signals. The tracking system comprises second processing means for generating a tracking error signal (PP(AC/DC)) defined by the addition of said first differential signal (PP(DC)) to a second differential signal (PP′(AC)), said second differential signal corresponding to a fraction of the difference in amplitude of the high-frequency components of said first and second output signals. Use: Optical disc player/writer.
摘要:
A demodulating system (100) for demodulating a phase-modulated input signal (Si) comprises: a complex demodulator (110), having a first input (111) for receiving the phase-modulated input signal (Si) and being designed to perform complex multiplication of this signal with an approximation of the inverse of the phase modulation; a spectrum analyzing device (130) receiving the demodulated product signal produced by the complex demodulator (110) and capable of analyzing the frequency spectrum of the demodulated product signal.
摘要:
The invention relates to a method of encoding user data into codevectors and to a corresponding method of decoding codevectors into user data. In order to be able to use the same ECC decoder for decoding of more than one type of data a method of encoding is proposed comprising the steps of: generating a first block of a fixed first number of data symbols by taking a fixed second number, being smaller than said first number, of user data symbols, and a fixed third number of dummy data symbols, and by arranging said user data symbols and said dummy data symbols in a predetermined order, encoding said first block of data symbols using an ECC encoder (2) to obtain a codeword having a fixed number of symbols, said codeword comprising said first block of data symbols and a second block of a fixed forth number of parity symbols, and generating a codevector by selecting a fifth predetermined number of user data symbols and a sixth predetermined number of parity symbols from said codeword, the sum of said fifth and sixth number being predetermined and smaller than the sum of said second and forth number.
摘要:
An information carrier for holding user information includes access information for accessing the user information, the access information being stored in a pre-determined first region on the information carrier. The information carrier further includes at least one further region different from the first region, the further region comprising dummy information.
摘要:
An ECC block is constituted by RS(248,216,33). Of a data length of 216 bytes (symbols), only 16 bytes are allocated to BCA data and the remaining 200 bytes are used for fixed data having a predetermined value. Using the fixed data of 200 bytes and the BCA data of 16 bytes, parities of 32 bytes (symbols) are calculated. Only the BCA data of 16 bytes and the parities of the former 16 bytes of the 32-byte parities, that is, a total of 32 bytes only, are recorded in a burst cutting area of an optical disc. In decoding, error correction processing is carried out by using the fixed data of 200 bytes. The unrecorded parities of 16 bytes are processed as having been erased. Thus, the error correction capability in a burst cutting area of an optical disc can be improved.
摘要:
An optical disc medium 10 having a wobbled track groove 12 includes three wobble patterns including a flat wobble pattern, a positive pulse wobble pattern, and a negative pulse wobble pattern. In the flat wobble pattern, the amplitude of the wobble from the lengthwise direction of the track groove is zero such that the track groove is flat. In the positive pulse wobble pattern, the amplitude of the wobble from the lengthwise direction of the track groove is positive such that the track groove is wobbled in a first direction perpendicular to the lengthwise direction. Further, in the negative pulse wobble pattern, the amplitude of the wobble from the lengthwise direction of the track groove is negative such that the track groove is wobbled in a second direction opposite to the first direction. Then, three data values can be recorded using three distinctive wobble patterns.
摘要:
A receiver is described for delivering a data sequence (ak) at a data rate 1/T from an analog signal (Sa), the receiver comprising: a) converting means (40) for generating a received sequence (rn) by sampling the analog signal (Sa) with a sample rate of 1/Ts, whereby the sample rate 1/Ts of the received sequence (rn) is controllable by a preset value (Pv); b) digital processing means (12) for delivering a processed sequence (yn) by processing the received sequence (rn); c) a first sample rate converter (13) converting the processed sequence (yn) into an equivalent processed sequence (ye) at the data rate 1/T, whereby the data rate of the equivalent processed sequence (ye) is controllable by a control signal (Sc); d) an error generator (14) for delivering an error sequence (ek) from the equivalent processed sequence (ye); e) a control signal generating means (15) for generating the control signal (Sc) dependent on the error sequence (ek); f) a detector (16) for deriving the data sequence (ak) from the equivalent processed sequence (ye),whereby the ratio between the sample rates 1/T and 1/Ts is substantially constant. Conventional synchronous receivers which comprise a Sample Rate Converter have the disadvantage that the digital processing is performed within the control loop of the SRC. The delay resulting from the digital processing contributes to the overall delay of the loop, which can lead to instabilities, especially when high bandwidths are require. Therefore the receiver of the invention does the digital processing outside the control loop. To keep the advantage that the digital processing can be done at a fixed rate, the converting means (40) are controlled by a preset value for keeping the ratio T/Ts constant.
摘要:
User data may be encoded into codevectors as follows. A first block of data symbols is generated by arranging a predetermined number of user data symbols and a predetermined number of dummy data symbols in a predetermined order. The first block of data symbols is encoded using an ECC encoder to obtain a codeword having a predetermined number of symbols, the codeword comprising the first block of data symbols and a second block of parity symbols. Then a codevector is generated containing less then all the user data symbols and parity symbols from the codeword. The codevector can be stored or transmitted. The codevector may be decoded by generating a codeword comprising dummy data symbols, a codevector, and filling symbols, arranged in a predetermined order. Then decoding the codeword using an ECC decoder to obtain the user data symbols.
摘要:
A method of storing/retrieving information to/from an optical disc by means of an optical system with a cut-off frequency νcut-off, above which frequencies cannot be detected, is disclosed. The invention relates to Run Length Limited encoded information. According to the invention, some frequencies of the encoded information can be higher than cut-off frequency of the optical system, such that the equation 4*(d+1)*Lcd*NA/λlaser