公开(公告)号：DE69723477D1

公开(公告)日：2003-08-14

申请号：DE69723477

申请日：1997-05-15

Applicant: IBM

Inventor： COKER DARREL ,  ELEFTHERIOU STAVROS ,  GALBRAITH LEO ,  HIRT WALTER

IPC: H03M13/41 ,  G11B20/10 ,  H04L25/03 ,  H04L25/497

Abstract: In a maximum likelihood sequence detector for symbol sequences which were equalized in a PR4 equalizer, noise prediction means (35) are provided including infinite impulse response (IIR) filtering, which have noise-whitening capabilities and are imbedded into the maximum likelihood detection process. The resulting INPML detector (10) can be implemented in digital or analog circuit technology. In addition, a DC-notch filter (44a) and a stochastic gradient procedure can be provided for DC offset compensation and for MR head or signal asymmetry compensation.

公开(公告)号：AT239332T

公开(公告)日：2003-05-15

申请号：AT96900002

申请日：1996-01-03

Applicant: IBM

Inventor： DE LANGE MARTIN ,  GFELLER FRITZ RUDOLF ,  HIRT WALTER

IPC: H04B10/114 ,  H04L1/00 ,  H04L7/04 ,  H04L12/28 ,  H04B10/10

Abstract: The communication system includes a robust physical layer header (RPLH) which can be understood by all participating stations. This robust header (50) at least comprises a preamble (52) consisting of frames forming a periodic sequence of pulses, the number of slots per frame and the frame content being known to all participating stations. The preamble serves for relative synchronization and carrier detection of the receiving stations. The robust header further comprises a unique synchronization word (53) which is used for absolute synchronization of the receiving stations. This synchronization word is followed by a control field (59) of fixed length and known structure. The control field informs the receiving stations of which modulation method will be used for the transmission of data. Pref. the control field also includes data for communication link and network control.

公开(公告)号：PL342885A1

公开(公告)日：2001-07-16

申请号：PL34288599

申请日：1999-04-21

Applicant: IBM

Inventor： GFELLER FRITZ ,  HIRT WALTER ,  INGHAM BRIAN R

IPC: H04B10/11 ,  H04L25/02 ,  H04B10/10

Abstract: The present invention provides an apparatus and a method for improved connectivity in wireless optical networks. Therefore at least two or more receiving units are used which receive an infrared signal and convert it to a digital signal. The digital signals represent data in the form of frames whereby each frame comprises at least a data field and a header field containing a preamble. A selector determines a measure related to the signal-to-noise ratio of the preamble and compares the measures in order to select the best suited signal for further processing.

公开(公告)号：SG72817A1

公开(公告)日：2000-05-23

申请号：SG1998001079

申请日：1998-05-19

Applicant: IBM

Inventor： COKER JONATHAN DARREL ,  ELEFTHERIOU EVANGELOS STAVROS ,  GALBRAITH RICHARD LEO ,  HIRT WALTER

IPC: G11B5/00 ,  G11B5/012 ,  G11B20/10 ,  H03M7/00 ,  H03M13/23 ,  H04L25/03 ,  H03M13/41

Abstract: A method and apparatus are provided for data detection for a partial-response maximum-likelihood (PRML) data detection channel in a direct access storage device. A class-IV partial response (PR4) signal is applied to a PR4 Viterbi detector to provide a PR4 Viterbi output and is applied to a first matching delay circuit to provide a delayed PR4 signal. The PR4 Viterbi output is subtracted from the delayed PR4 signal and a resulting signal is applied to a first filter having a frequency response of 1/(1- alpha D2). The filtered output signal is applied to a second filter providing a second filtered output signal. The PR4 Viterbi output is applied to a second matching delay circuit to provide a delayed PR4 Viterbi output signal. The delayed PR4 Viterbi output is corrected responsive to the second filtered output signal. The first filter is an infinite impulse response (IIR) filter and the filtered output signal represents whitened noise and modified PRML error events. The second filter is a matched filter used to identify dominant error events.

公开(公告)号：CZ204098A3

公开(公告)日：1998-10-14

申请号：CZ204098

申请日：1996-01-03

Applicant: IBM

Inventor： DE LANGE MARTIN ,  GFELLER FRITZ RUDOLF ,  HIRT WALTER

IPC: H04B10/114 ,  H04L1/00 ,  H04L7/04 ,  H04L12/28 ,  H04B10/10

Abstract: The communication system includes a robust physical layer header (RPLH) which can be understood by all participating stations. This robust header (50) at least comprises a preamble (52) consisting of frames forming a periodic sequence of pulses, the number of slots per frame and the frame content being known to all participating stations. The preamble serves for relative synchronization and carrier detection of the receiving stations. The robust header further comprises a unique synchronization word (53) which is used for absolute synchronization of the receiving stations. This synchronization word is followed by a control field (59) of fixed length and known structure. The control field informs the receiving stations of which modulation method will be used for the transmission of data. Pref. the control field also includes data for communication link and network control.

公开(公告)号：DE3676825D1

公开(公告)日：1991-02-14

申请号：DE3676825

申请日：1986-08-05

Applicant: IBM

Inventor： HIRT WALTER ,  SCHOTT WOLFGANG HANS

IPC: G11B20/10 ,  G11B20/18 ,  G11B5/09

Abstract: In the readback apparatus of a magnetic recording system operating in accordance with the partial-response maximum-likelihood (PRML) technique, a variable-gain amplifier (VGA) and a maximum-likelihood sequence detector (ML DET) plus a gain control loop are provided. The detector (19) is designed to operate on input signals (y min ) having nominal discrete signal amplitudes (a, 0, -a) and it furnishes discrete output signals ( @) having such nominal signal amplitudes. The gain control loop is responsive to input (27) and output (29) signals of the detector, and it has charge-pump circuitry (37, 39, 41, 43) for generating a gain control signal (Vc = Vg) for the variable gain amplifier (35). To enable proper operation of the system even in case of short-time signal amplitude drops due to media defects, biasing means (49) are provided such that the gain (g) is adjusted to a value which causes the signal amplitudes at the input (27) of the detector to be weighted multiples (ca, 0, -ca) of the nominal amplitude values (a, 0, -a).

公开(公告)号：DE602004011370D1

公开(公告)日：2008-03-06

申请号：DE602004011370

申请日：2004-07-08

Applicant: IBM

Inventor： HIRT WALTER ,  WEISENHORN MARTIN

IPC: H04L12/28 ,  H04B1/69 ,  H04J14/00 ,  H04J99/00

公开(公告)号：MY126421A

公开(公告)日：2006-09-29

申请号：MYPI9902893

申请日：1999-07-09

Applicant: IBM

Inventor： HASSNER MARTIN AURELIANO ,  HEISE NYLES ,  HIRT WALTER ,  TRAGER BARRY MARSHALL

IPC: G11B20/14 ,  G11B20/10 ,  H03M7/00 ,  H03M5/14 ,  H03M7/14 ,  H03M13/00

Abstract: A METHOD AND MEANS FOR REDUCING HIGH-DUTY-CYCLE UNCONSTRAINED BINARY SIGNAL SEQUENCES IN STORAGE AND COMMUNICATION PROCESSES AND SYSTEMS BY INVERTIBLY MAPPING SUCH SEQUENCES INTO A (L,K) RATE 2/3 RLL CODESTREAM CONSTRAINED TO A DUTY CYCLE SUBSTANTIALLY APPROXIMATING ONE-THIRD. THAT IS, BINARY SEQUENCES ORDINARILY MAPPING INTO HIGH-DUTY-CYCLE RLLCODED SEQUENCES ARE EITHER INHIBITED FROM REPEATING INDEFINITELY OR EXCLUDED.(FIG 1)

公开(公告)号：MY120295A

公开(公告)日：2005-10-31

申请号：MYPI9605415

申请日：1996-12-20

Applicant: IBM

Inventor： LANGE MARTIN DE ,  GFELLER FRITZ RUDOLF ,  HIRT WALTER

IPC: H04B7/00

Abstract: DISCLOSED IS AN OPTICAL COMMUNICATION SYSTEM ENABLING COMMUNICATION BETWEEN SEVERAL CO-EXISTING TRANSMITTING AND RECEIVING STATIONS. IN ORDER TO ALLOW COMMUNICATION BETWEEN THE CO-EXISTING STATIONS, A ROBUST PHYSICAL LAYER HEADER (RPLH; 50) IS EMPLOYED WHICH CAN BE UNDERSTOOD BY ALL PARTICIPATING STATIONS. THIS ROBUST HEADER (50) AT LEAST COMPRISES A PREAMBLE (52) CONSISTING OF FRAMES FORMING A PERIODIC SEQUENCE OF PULSES, THE NUMBER OF SLOTS PER FRAME AND THE FRAME CONTENT BEING KNOWN TO ALL PARTICIPATING STATIONS. THE PREAMBLE (52) SERVES FOR RELATIVE SYNCHRONIZATION AND CARRIER DETECTION OF THE RECEIVING STATIONS. THE ROBUST HEADER (50) FURTHER COMPRISES A UNIQUE SYNCHRONIZATION WORD (53) USED FOR ABSOLUTE SYNCHRONIZATION OF THE RECEIVING STATIONS. THIS SYNCHRONIZATION WORD (53) IS FOLLOWED BY A CONTROL FIELD (59) OF FIXED LENGTH AND KNOWN STRUCTURE. BY MEANS OF THIS CONTROL FIELD (59) THE RECEIVING STATIONS ARE INFORMED WHICH MODULATION METHOD WILL BE USED FOR THE TRANSMISSION OF DATA. UNDER CERTAIN CIRCUMSTANCES IT IS ALSO USEFUL TO PROVIDE OTHER CONTROL INFORMATION IN SAID CONTROL FIELD (59) FOR COMMUNICATION LINK AND NETWORK CONTROL. FURTHERMORE, INFORMATION MAY BE EXCHANGED TO ALLOW NEGOTIATION AND/OR ADAPTATION OF THE DATA RATE USED FOR TRANSMISSION. THIS ALLOWS TO OPTIMIZE THE THROUGHPUT DEPENDING ON THE CONDITIONS (QUALITY) ON THE CHANNEL.

公开(公告)号：CA2241937C

公开(公告)日：2004-04-27

申请号：CA2241937

申请日：1996-01-03

Applicant: IBM

Inventor： HIRT WALTER ,  DE LANGE MARTIN ,  GFELLER FRITZ RUDOLF

IPC: H04B10/114 ,  H04L1/00 ,  H04L7/04 ,  H04L12/28 ,  H04B10/04 ,  H04B10/06 ,  H04B10/10

Abstract: Disclosed is an optical communication system enabling communication between several co-existing transmitting and receiving stations. In order to allow communication between the co-existing stations, a robust physical layer header (RPLH; 50) is employed which can be understood by all participating stations. This robust header (50) at least comprises a preamble (52) consisting of frames forming a periodic sequence of pulses, the number of slots per frame and the frame content bein g known to all participating stations. The preamble (52) serves for relative synchronization and carrier detection of the receiving stations . The robust header (50) further comprises a unique synchronization word (53) used for absolute synchronization of the receiving stations. This synchronization word (53) is followed by a control field (59) of fixed length and known structure. By means of this control field (59) the receiving stations are informed which modulation method will be used for the transmission of data. Under certain circumstances it is also useful to provide other control information in said control field (59) for communication link and network control. Furthermore, information ma y be exchanged to allow negotiation and/or adaptation of the data rate used for transmission. This allows to optimize the throughput depending on the conditions (quality) on the channel.