Classifier for high speed voiceband digital data modem signals

Details Classifier for high speed voiceband digital data modem signals Classifier for high speed voiceband digital data modem signals

1990-06-05

1990-12-18

Kemeny, Emanuel S.

Electrical audio signal processing systems and devices

One-way audio signal program distribution

Public address system

381 46, G10L 500

Patent

active

049792113

ABSTRACT:
An unknown voiceband digital data modem signal is classified as being generated by one of a plurality of possible digital data modem signal sources, e.g., CCITT V.29, CCITT V.32, CCITT V.33 or the like digital data modems. Classification is achieved by employing a blind, i.e., self-recovering, adaptive equalizer to remove effects of linear channel impairments and to generate a sequence of magnitude estimates at the symbol rate of the unknown voiceband digital data modem signal. The sequence of magnitude estimates is compared to predetermined representations of known possible voiceband digital data modem signals and the results of the comparison are used to identify the digital data modem signal source of the signal. In one example, the predetermined representations are templates of conditional density functions of magnitude estimates obtained from known voiceband digital data modem signals generated by corresponding digital data modem signal sources. The symbol rate detector detects bit rate and type of modulation.

REFERENCES:
patent: 4542525 (1985-09-01), Hopf
patent: 4633499 (1986-12-01), Nishioka
Digital Communication, Edward A. Lee et al., Kluwer Academic Publishers, 1988, Sections 6.1-6.5, pp. 146-206.
IEEE Transactions on Communications, vol. COM-28, No. 11, Nov., 1980, "Self-Recovering Equalization and Carrier Tracking in Two-Dimensional Data Communication Systems" by Dominique N. Godard, pp. 1867-1875.
IEEE Transactions on Communications, vol. COM-30, No. 4, Apr. 1982, "Highly Sensitive Speech Detector and High-Speed Voiceband Data Discriminator in DSI-ADPCM Systems" by Yohtaro Yatsuzuka, pp. 739-750.

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