Pulse or digital communications – Equalizers – Automatic
Patent
1993-09-15
1995-10-03
Chin, Stephen
Pulse or digital communications
Equalizers
Automatic
375219, 375257, 375350, 379398, 379400, 379411, 379416, 370 6, 333 18, 333 28R, H03H 730, H03H 740
Patent
active
054558433
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.
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patent: 5271037 (1993-12-01), Szechenyi
Data Communications, vol. 19, No. 12, Sep. 21, 1990, pp. 41,42,44,46,48,50.
Data Communication, vol. 19, No. 8, Jun. 21, 1990, pp. 85,86,88,89.
IBM TDB vol. 32, No. 6A Nov. 1989 pp. 273-274.
Cherubini Giovanni
Oelcer Sedat
Ungerboeck Gottfried
Chin Stephen
Herndon Jerry W.
International Business Machines - Corporation
Le Amanda
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