公开(公告)号：DE69225709D1

公开(公告)日：1998-07-02

申请号：DE69225709

申请日：1992-10-15

Applicant: IBM

Inventor： CHERUBINI GIOVANNI DR ,  OELCER SEDAT DR ,  UNGERBOECK GOTTFRIED DR

IPC: H04B3/14

Abstract: Adaptive analog equalizer permitting 16 Mbit/s token ring (TR) transmission over unshielded twisted-pair (UTP) cables. The equalizer (29) is located at the wiring concentrator (25), and consists of a variable and a fixed filter section. The existing TR receiver (49) and transmitter (53) remain unchanged. To compensate for distortion introduced by the cable section (19b) preceding the equalizer, the level of the signal (B) at the equalizer output (35) is used as a control criterion. The additional distortion contributed by the cable section (21a) following the equalizer is accounted for by measuring the level of the signal (D) received from the transmitter (53) of the next TR station. By these two measurements, the equalizer is adjusted such that the cable-length dependent distortion is eliminated at the next receiver (49). Transmitted Manchester-coded signals are received essentially distortion-free for cable attenuation ranging between 0 and 25 dB at 16 MHz, corresponding to zero and maximum cable lengths between TR stations. The amplification provided by equalization at the concentrator significantly mitigates also the effect of near-end crosstalk from the transmitter into the receiver input of TR stations.

公开(公告)号：DE68915762D1

公开(公告)日：1994-07-07

申请号：DE68915762

申请日：1989-08-21

Applicant: IBM

Inventor： UNGERBOECK GOTTFRIED DR

IPC: H04L27/22 ,  H04L7/00 ,  H04L7/027 ,  H04L7/033 ,  H04L7/10

Abstract: For a modem receiver using an adaptive equalizer with fractional tap spacing, method and apparatus are disclosed for controlling the sample-timing phase. By evaluating bandedge components of the received signal in a particular way, a timing-phase vector signal is derived which is independent of the signal energy at the bandedges and of the quality of frequency separation of the filters for the bandedge signals. After an initial period, the current timing-phase vector signal is captured and stored as a reference. Thereafter, the sampling phase of the receiver is kept at its initial random value, represented by the stored reference timing-phase vector. The necessity to initially change the sampling phase in the receiver to a value which is forced by the received signal is avoided.

公开(公告)号：DE3174130D1

公开(公告)日：1986-04-24

申请号：DE3174130

申请日：1981-08-19

Applicant: IBM

Inventor： CHEVILLAT PIERRE DR ,  KAESER HANSPETER ,  MAIWALD DIETRICH DR ,  UNGERBOECK GOTTFRIED DR

IPC: G06F9/30 ,  G06F7/00 ,  G06F9/315 ,  G06F15/78 ,  G06F17/10 ,  G06F15/06