Pulse or digital communications – Repeaters – Testing
Patent
1988-08-02
1990-02-06
Safourek, Benedict V.
Pulse or digital communications
Repeaters
Testing
333 18, H04B 306
Patent
active
048993662
ABSTRACT:
In a modem receiver having a fixed sample rate relative to incoming symbols and a tapped delay adaptive equalizer with fractional tap spacing, coefficients used in the equalization computations are rotated relative to a reference tap in order to compensate for relative drift between incoming signals, representing real (i.e. non-training) data, and the clock controlling sampling. By itself, such rotation would tend to distort received data by shifting the sampling phase away from the center of the received symbols. Logic means included herewith operates to prevent such distortion, so that the integrity of the data output of the receiver is unaffected by the rotation. In the disclosed embodiment, such logic means operates to shift the phase of the "sum of products" computation (product of data and tap coefficients) relative to the flow of data into the fractionally spaced delay network. Since the present receiver does not require synchronization with incoming symbols it is well adapted to function in environments where such synchronization would be difficult to provide; for example, in situations where data transmitted at various baud rates is received via a digital carrier trunk and requires equalization or comparable filter processing.
REFERENCES:
patent: 3508153 (1970-04-01), Gerrish et al.
patent: 3694752 (1972-09-01), Gibson
patent: 3697689 (1972-10-01), Gibson
patent: 3868603 (1975-02-01), Guidoux
patent: 4145747 (1979-03-01), Sakaki et al.
patent: 4146840 (1979-03-01), McRae et al.
patent: 4285061 (1981-08-01), Ho
patent: 4343759 (1982-08-01), Kustka et al.
patent: 4384355 (1983-05-01), Werner
patent: 4550415 (1985-10-01), Debus, Jr. et al.
G. Ungerboek, "Fractional Tap-Spacing Equalizers and Consequences for Clock recovery in Data Modems", IEEE Trans. on Communications, vol. Com. 24, No. 8, Aug. 1976, pp. 856-864.
Cowan, C. F. N., Grant, P. M., "Adaptive Filters", Prentice-Hall Inc., 1985.
Rabiner, L. R., Gold, B., "Theory and Application of Digital Signal Processing", Prentice-Hall, 1975.
Hartman, P., Bynam, B., "Adaptive Equalization for Digital Microwave Radio Systems", IEEE International Conference on Communications, Paper 8.5, 1980.
Taylor, N. G., "Adaptive Antennas", Special Issue, Proceeding of IEE, vol. 130, No. 1, pp. 1 55, Jan. 1983.
Makhoul, J., Vishwanathan, R., "Adaptive Lattice Methods for Linear Prediction", Proceedings of ICASSP 1978, pp. 83-86.
Holt, L., Stueflotten, S., "A New Digital Echo Canceler for Two Wire Subscriber Lines", IEEE Trans. COM-29, No. 11, pp. 1573-1581, Nov. 1981.
Haykin, S., Cadzov, J. A., "Spectral Estimation", Special Issue, Proceeding of IEE, vol. 70, No. 9, Sep. 1982.
Ungerboeck, G., "Adaptive Equalization Techniques in Voiceband Data Transmission", Proceedings of Intl Conf on Communicatoins, Jun. 1980, pp. 8.4.1-8.4.6.
P. Thomas, "The Design and Implementation of a CCITT V.32 Modem on a General Purpose Digital Signal Processing Microprocessor", Proceedings of the IEEE International Conf. on Communications, 1987, pp. 12.5.1 to 12.5.4.
Desblache et al, IBM Technical Disclosure Bulletin, v. 21, No. 5, Oct. 1978, at pp. 1916-1918.
Davis Gordon T.
Mandalia Baiju D.
Downey Joseph T.
International Business Machines - Corporation
Lieber Robert
Safourek Benedict V.
LandOfFree
Tap rotation n fractionally spaced equalizer to compensate for d does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Tap rotation n fractionally spaced equalizer to compensate for d, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Tap rotation n fractionally spaced equalizer to compensate for d will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-446019