Patent Number: 6,839,382

Title: System, methods and computer program products for identifying digital impairments in modem signals using signature analysis and signal level comparison analysis

Abstract: Digital impairments, including Robbed Bit Signaling (RBS) and impairments due to digital attenuation PAD (Packet Assembler/Disassembler) devices, may be identified in sets of Pulse Code Modulation (PCM) signal levels, such as sets of Digital Impairment Learning (DIL) signals transmitted from a server modem to a client modem during a plurality of DIL levels. Both signature analysis and signal level comparison analysis are preformed on the signals to identify digital impairments. Signature analysis compresses the set of signal levels into a signature. Digital impairments are determined based on the signature. In a preferred embodiment, the PCM signal levels are compressed into a signature by identifying clusters and/or skips. PCM signal level comparison analysis uses differences, between PCM signals and models of signals having various digital impairments. By using both techniques combination, the strengths of each technique are utilized while the weaknesses of each techniques are avoided.

Inventors: Davis; Gordon Taylor (Chapel Hill, NC), Dholakia; Ajay (Gattikon, CH), Hwang; Dongming (Cary, NC), Ware; Malcolm Scott (Raleigh, NC), Ye; Hua (Durham, NC)

Assignee: International Business Machines Corporation

International Classification: H04L 5/16 (20060101); H04L 005/16 ()

Expiration Date: 01/04/2022