Adaptive noise cancellation

Details Adaptive noise cancellation Adaptive noise cancellation

1993-03-05

1995-11-07

Urban, Edward F.

Telecommunications

Receiver or analog modulated signal frequency converter

Noise or interference elimination

375349, H04B 112

Patent

active

054654130

ABSTRACT:
Method and apparatus for reducing or cancelling impulse noise from a signal containing noise. The desired noise-free signal is assumed to have a representative frequency .omega..sub.3, but may have a range of frequencies adjacent to this frequency, and is assumed to have substantially zero amplitude for all frequencies .omega.<.omega..sub.1 and/or for all frequencies .omega.>.omega..sub.2, where .omega..sub.1 <.omega..sub.3 <.omega..sub.2 or .omega..sub.1 <.omega..sub.2. An input (noisy) signal is filtered and analyzed in a narrow frequency region surrounding .omega.=.omega..sub.1 and/or a narrow frequency region surrounding .omega.=.omega..sub.2 to obtain one or two output signal components n.sub.1 (t) and/or n.sub.2 (t), respectively, that, ideally, contain no contribution from the desired signal. The input signal is also filtered and analyzed in a narrow frequency region surrounding .omega.=.omega..sub.3 to obtain an output signal s(t)+n.sub.3 (t) component including the desired signal s(t). A linear combination of signals, such as S(t)=s(t)+n.sub.3 (t).+-.[n.sub.1 (t)n.sub.2 (1)] .sup.1/2, or S(t)=s(t)+n.sub.3 (t)+.alpha.exp(-j.phi.) [n.sub.1 (t)n.sub.2 (1)].sup.1/2,or S(t)=s(t)+n.sub.3 (t).+-.n.sub.k (t) (k=1,2), or S(t)=s(t)+n.sub.3 (t)+exp(-j.phi.)n.sub.k (t), or S(t)=s(t)+n.sub.3 (t)+[exp(-j.psi.1)n.sub.1 (t)+exp(-j.psi.2) n.sub.2 (t)]/2, or S(t)=s(t)+n.sub.3 (t)+.alpha.[exp(-j.psi.) n.sub.1 (t)+exp(-j.psi.) n.sub.2 (t)]/2, is formed as a circuit output signal, and the .+-. sign and/or the multiplier .alpha. and/or the phase angles .phi., .psi.1, .psi.2 and .psi. are chosen to minimize the contribution of noise to S(t), according to a selected quantitative error measure. Three such error measures are the displacement of a signal from the median of a reference signal,the cumulative variation of a signal, and the least mean square value of a signal. Other combinations of the signals n.sub.1 (t) and n.sub.2 (t), replacing the (complex) arithmetic mean and geometric mean, may be used for the linear combination signal S(t). Methods for computation of the phase angles .phi. , .psi.1, .psi.2 and .psi. are also disclosed.

REFERENCES:
patent: 3541458 (1970-11-01), Klund
patent: 4067013 (1978-01-01), Smith
patent: 4092603 (1978-05-01), Harrington
patent: 4177430 (1979-12-01), Paul
patent: 4220926 (1980-09-01), Buckner
patent: 4287475 (1981-09-01), Eaton et al.
patent: 4363138 (1982-12-01), Franklin et al.
patent: 4537200 (1985-08-01), Widrow
patent: 4649505 (1987-03-01), Zinsnower, Jr. et al.
patent: 4719466 (1988-01-01), Farina et al.
patent: 4792964 (1988-12-01), Yoshida
patent: 4847860 (1989-07-01), Robert
patent: 4901150 (1990-02-01), Klingelhofer et al.
patent: 4912398 (1990-04-01), Jove et al.
patent: 5008903 (1991-04-01), Betts et al.
patent: 5018088 (1991-05-01), Higbie

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