Communication of an impairment learning sequence according to an impairment ...

(54) COMMUNICATION OF AN IMPAIRMENT

LEARNING SEQUENCE ACCORDING TO AN
IMPAIRMENT LEARNING SEQUENCE
DESCRIPTOR

(75) Inventor: Sverrir Olafsson, Reykjavik (IS)

(73) Assignee: Conexant Systems Inc., Newport Beach, CA (US)

( * ) Notice: Subject to any disclaimer, the term ol this patent is extended or adjusted under 35 U.S.C. 154(b) by 0 days.

(21) Appl. No.: 09/956,207

(22) Filed: Sep. 19, 2001

Related U.S. Application Data

(63) Continuation of application No. 08/969,971, filed on Nov. 13, 1997, now Pat. No. 6,332,009, which is a continuationin-part of application No. 08/922,851, filed on Sep. 3,1997, now Pat. No. 6,212,247.

(51) Int. C I. 11041. 7/00

(52) U.S. CI 375/368; 375/364; 370/509

(58) Field of Search 375/358, 221,

375/222, 356, 368, 357, 364; 370/509, 503, 514, 510, 515, 511, 512, 513

(56) References Cited

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FOREIGN PATENT DOCUMENTS

EP 0669740 A2 8/1995

A modem system includes a programmable synchronization signal format that can be configured at a first modem in response to a request received from a second modem. The synchronization signal format may define a number ol parameters ol the synchronization signal, such as the sign pattern for symbols transmitted by the first modem during a training sequence. The specific parameters ol the synchronization signal format may be associated with the design and operation ol the second modem. For example, the particular timing recovery and automatic gain control schemes used by the receiver portion ol the second modem may be optimally initialized with a synchronization signal having a specific length, amplitude, or spectrum. In one embodiment, a synchronization signal is configured to convey a single frequency tone for use during a synchronization routine. The modem system may also employ similar techniques to generate, transmit, and analyze a programmable line impairment learning signal. Such a programmable learning signal may be formatted such that characteristics of the communication channel are determined for individual signal points. In response to a particular learning signal, the second modem selects a number of preferred signal points for use by the modem system during subsequent data transmission.

24 Claims, 6 Drawing Sheets