Communications – electrical: acoustic wave systems and devices – Receiver circuitry
Patent
1988-06-23
1990-02-20
Tarcza, Thomas H.
Communications, electrical: acoustic wave systems and devices
Receiver circuitry
367901, 36472418, 379411, H04B 106, H04B 323
Patent
active
049032470
ABSTRACT:
A digital echo canceller [1] with a good protection against double-talk comprises a first filter [9] for the echo cancellation proper, a second adaptive filter [11] for making continuously adapted filter coefficients available to the first filter [9] and gate means [15] which will only apply the adapted filter coefficients to the first filter [9] if certain conditions are satisfied. In the echo canceller [1] a specific filter combination is used, in which the first filter [9] is a time-domain programmable filter (TDPF) and the second filter [11] is a frequency-domain block-adaptive (FDAF), and further means [20,20(1)] are provided that are arranged in cascade with the gate means [15] for transforming the frequency-domain filter coefficients [W(p;m)] of the FDAF [11] into time-domain filter coefficients [w(i;m)] for the TDPF [9]. These measures result in the advantages of a negligible delay in the echo cancellation by the TDPF [9], and of the possibility to improve in a simple manner the convergence behavior of the FDAF [11] and considerably reduce its computational complexity.
REFERENCES:
patent: 4736414 (1988-04-01), Montagna et al.
patent: 4807173 (1989-02-01), Sommen et al.
K. Ochiai et al., "Echo Canceler with Two Echo Path Models", IEEE Transactions on Communications, vol. COM-25, No. 6, Jun. 1977, pp. 589-595.
C. W. K. Gritton and D. W. Lin, "Echo Cancellation Algorithms", IEEE ASSP Magazine Apr. 1984, pp. 30-38.
G. A. Clark et al., "A Unified Approach to Time-and Frequency-Domain Realization of FIR Adaptive Digital Filters", IEEE Transactions on Acoustics, Speech and Signal Processing, vol. ASSP-31, No. 5, Oct. 1983, pp. 1073-1083.
D. Mansour et al., "Unconstrained Frequency-Domain Adaptive Filter," IEEE Transactions on Acoustics, Speech, and Signal Processing, vol. ASSP-30, No. 5, Oct. 1982, pp. 726-734.
Kotmans Hendrik J.
van de Laar Franciscus A. M.
van Gerwen Petrus J.
Briody Thomas A.
Haken Jack E.
Pihulk Daniel T.
Slobod Jack D.
Tarcza Thomas H.
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