Source: http://www.google.com/patents/US4683590?dq=6,202,008
Timestamp: 2016-07-27 06:38:24
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Matched Legal Cases: ['art 110', 'art 80', 'art 300', 'art 80', 'art 100', 'art 100', 'art 160', 'art 120', 'art 160', 'art 100', 'art 120', 'art 130', 'art 100']

Patent US4683590 - Inverse control system - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Sign inPatentsAn inverse control system is disclosed, which comprises FIR filters provided between transmitting elements at n (n=2, 3, . . . ) input points of a linear FIR system and a common signal source, for an inverse control such as to provide desired impulse responses between the signal source and m (n>m) output...http://www.google.com/patents/US4683590?utm_source=gb-gplus-sharePatent US4683590 - Inverse control systemAdvanced Patent SearchPublication numberUS4683590 APublication typeGrantApplication numberUS 06/839,677Publication dateJul 28, 1987Filing dateMar 14, 1986Priority dateMar 18, 1985Fee statusPaidAlso published asCA1242003A, CA1242003A1, DE3686497D1, DE3686497T2, EP0195416A2, EP0195416A3, EP0195416B1Publication number06839677, 839677, US 4683590 A, US 4683590A, US-A-4683590, US4683590 A, US4683590AInventorsMasato Miyoshi, Yutaka Kaneda, Juro OhgaOriginal AssigneeNippon Telegraph And Telphone CorporationExport CitationBiBTeX, EndNote, RefManPatent Citations (5), Referenced by (44), Classifications (11), Legal Events (4) External Links: USPTO, USPTO Assignment, EspacenetInverse control system
1. An inverse control system for an n-input m-output (m being 1 or a greater integer, n being an integer greater than m) linear finite impulse response (FIR) system defining n�m signal transmission channels between n input points and m output points, with n transmitting elements being disposed at the respective n input points for providing signals to said linear FIR system, whereinsaid inverse control system is disposed between said n transmitting elements and a common signal source for effecting an inverse control such as to provide desired impulse responses between said signal source and said m output points; said inverse control system comprises n FIR filters disposed between said signal source and respective said n transmitting elements; a j-th (j=1, 2, . . . , n) one of said FIR filters connected to a j-th one of said input points through an associated one of said transmitting elements has a number Li of taps which satisfies relationships represented by ##EQU25## for all i=1, 2, . . . , m and j=1, 2, . . . , n where wij is the number of discrete signals representing the impulse response gij (k) of said signal transmission channel between said j-th input point and an i-th (i=1, 2, . . . , m) one of said m output points of said linear FIR system and Pi is the number of discrete signals representing said desired impulse response ri (k) between said signal source and said i-th output point; and said j-th FIR filter having filter coefficients hj (k) (j=1, 2, . . . , n) satisfying a relationship ##EQU26## for all i=1, 2, . . . , m where ○* represents a discrete convolution. 2. An inverse control system for an m-input n-output (m being 1 or greater integer, n being an integer greater than m) linear finite impulse response (FIR) system defining m�n signal transmission channels between m input points and n output points, with n receiving elements being disposed at the respective n output points for receiving signals provided to said linear FIR system, whereinsaid inverse control system is disposed between said n receiving elements and n input terminals of adder means for effecting an inverse control such as to provide desired impulse responses between the output side of said adder means and said m input points; said inverse control system comprises n FIR filters disposed between said n receiving elements and the n input terminals of said adder means, respectively; a j-th(j=1, 2, . . . , n) one of said n FIR filters connected to a j-th one of said output points through an associated one of said receiving elements having a number Li of taps which satisfies the relationships represented by ##EQU27## for all i=1, 2, . . . , m and j=1, 2, . . . , n where wij is the number of discrete signals representing the impulse response gij (k) of said signal transmission channel between an i-th one of said m input points and the j-th output point of said linear FIR system and Pi is the number of discrete signals representing said desired impulse response ri (k) between said i-th input point and output side of said adder means; and said j-th FIR filter having filter coefficients hj (k) satisfying a relationship ##EQU28## for all i=1, 2, . . . , m where ○* represents a discrete convolution. 3. The inverse control system according to claim 1 or 2, wherein said desired impulse response ri (k) is represented by Pi discrete signals satisfying a relationship Pi &#8806;wij +Lj -1                       (3) for all i=1, 2, . . . , m and j=1, 2, . . . , n and said j-th FIR filter has a number Lj of taps satisfying a relationship ##EQU29## for all j=1, 2, . . . , n. 4. The inverse control system according to claim 1 or 2, whereinn=m+1. 5. The inverse control system according to claim 3, whereinn=m+1. 6. The inverse control system according to claim 1 or 2, which further comprises coefficients setting means for computing the filter coefficients hj (k) (j=1, 2, . . . , n) satisfying the relationships (1a), (1b) and (2) by utilizing said impulse response gij (k) and desired impulse response ri (k) and setting the computed filter coefficients hj (k) (j=1, 2, . . . , n) for said j-th FIR filter.
7. The inverse control system according to claim 6, wherein representing the relationship (2) by an expression R=G�H said coefficients setting means computes the filter coefficients hj (k) (j=1, 2, . . . , n) using a relationship H=GT (G�GT)-1 �R where ##EQU30## 8. The inverse control system according to claim 3, which further comprises coefficients setting means for computing the filter coefficients hj (k) satisfying the relations (2), (3) and (4) by utilizing said impulse response gij (k) and desired impulse response ri (k) and setting the computed filter coefficients hj (k) (j=1, 2, . . . , n) for said j-th FIR filter.
9. The inverse control system according to claim 8, wherein representing the relationship (2) by an expression R=G�H said coefficients setting means computes the filter coefficients hj (k) using a relationship H=GT (G�GT)-1 �R where ##EQU31## 10. The inverse control system according to claim 8, wherein representing the relationship (2) by an expression R=G�H said coefficients setting means computes the filter coefficients hj (k) (j=1, 2, . . . , n) using a relation H=G-1 �R where ##EQU32## 11. The inverse control system according to claim 6, wherein said coefficients setting means computes the filter coefficients hj (k) (j=1, 2, . . . , n) satisfying the relationship (2) by a recursive computation.
12. The inverse control system according to claim 11, wherein representing the relationship (2) by an expression R=G�H said coefficients setting means performs the recursive computation expressed as H(q+1)=H(q)+&#945;(q)�GT �(R-G�H(q)) (5) where q is the number of times the argorithm of the equation (5) is repeatedly executed, α(q) is a step size indicating an amount by which to move from H(q), and ##EQU33## 13. The inverse control system according to claim 8, wherein said coefficients setting means computes the filter coefficients hj (k) (j=1, 2, . . . , n) satisfying the relationship (2) through recursive computation.
14. The inverse control system according to claim 13, wherein representing the relationship (2) by an expression R=G�H said coefficients setting means performs the recursive computation expressed as H=(q+1)=H(q)+&#945;(q)�GT (R=G�H(q)) (6) where q is the number of times the argorithm of the equation (6) is repeatedly executed, α(q) is a step size indicating an amount by which to move from H(q), and ##EQU34## 15. The inverse control system according to claim 6, which further comprises a waveform memory for storing each said impulse response gij (k) of said linear FIR system to be read out therefrom and supplied to said coefficients setting means.
A first aspect of the invention is applied to an n-input m-output (n>m, m being 1 or a greater integer) linear FIR system having m�n FIR signal transmission channels between the n input points and m output points. Signals are fed into the linear system from n transmitting elements disposed at n input points. An inverse control system according to the invention is provided between these transmitting elements and a common signal source to control signals fed to the transmitting elements to provide desired impulse responses between the signal source and m output points. In the inverse control system according to the first aspect of the invention, FIR filters are provided between the signal source and n transmitting elements. When representing the impulse response gij (k) between the j-th one of the n input points and the i-th one of the m output points of the system with wij discrete signals and representing the desired impulse response ir (k) between the signal source and i-th output point with Pi discrete signals, the j-th FIR filter connected to the j-th input point through a transmitting element has a number L.sub. j of taps satisfying the relationships, ##EQU7## for all i=1, 2, . . . , m and j=1, 2, . . . , n and the coefficients hj (k) of the j-th FIR filter satisfies ##EQU8## for all i=1, 2, . . . , m, where ○ represents the discrete convolution.
A second aspect according to the invention is applied to an m-input n-output (n>m, m being 1 or a greater integer) linear FIR system having m�n FIR signal transmission channels between the m input points and n output points, where signals provided from the linear system are received by receiving elements disposed at the n output points. An inverse control system according to the invention is provided between the n receiving elements and an adder to control the outputs of the receiving elements to provide desired impulse response between the output of the adder and m input points. In the inverse control system, n FIR filters are provided between the n receiving elements and n input terminals of the adder. When representing the impulse response gij (k) (i=1, 2, . . . , m; j=1, 2, . . . , n) of the system between the i-th one of the m input points and j-th one of the n output points with wij discrete signals and representing the desired impulse response ri (k) (i=1, 2, . . . , m) between the i-th input point and the output of the adder with Pi discrete signals, the j-th filter connected to the j-th output point through a transmitting element has a number Lj of taps satisfying the relationships (3) and (4), and the coefficients hj (k) (j=1, 2, . . . , n) of the j-th FIR filter satisfy the equation (5).
1=g11 (z)�h1 (z)+g12 (z)�h2 (z) (7)
h1 '(z)=h1 (z)+g12 (z)�u(z)        (10a)
h2 '(z)=h2 (z)-g11 (z)�u(z)        (10b)
deg h1 '(z)=deg g12 (z)�u(z)&#8807;dg2 ( 11a)
deg h2 '(z)=deg g11 (z)�u(z)&#8807;dg1 ( 11b)
R=G�H                                             (13)
H=(H1 T H2 T)T R=(R1 T)T and ##EQU9## Under the principles of linear discrete convolution, the convolution matrix G on the right side of the equation (13) is a (w1j +Lj -1)�(L1 +L2) matrix where j=1, 2. The equation (13) can be solved as follows.
H=G-1 �R                                     (15)
H=GT �(G�GT)-1 �R (18)
H(q+1)=H(q)+&#945;(q)�GT �[R-G�H(q)](20)
H=G-1 �R                                     (23)
In this embodiment, m (m≦n-1) microphones 111 to 11m are disposed at respective controlled points, i.e., the output points of the n-input m-output linear FIR system. When an impulse is fed to the A/D converter 30, the outputs of the microphones 111 to 11m are fed to a waveform memory 60 through a switch 200. In the waveform memory 60 are thus stored m�n impulse response vectors Gij =(gij (1) gij (2) . . . gij (wij))T between the n loudspeakers 11 to 1n and m microphones 111 to 11m, where gij (k) is an impulse response, k is an integer, i=1, 2, . . . , m, and j=1, 2, . . . , n.
(6) G and GT (or E) are fed to respective input terminals 101-1 and 101-2 of the matrix multiplier 101, and their product G�GT (or G) is computed and output.
(7) From the output of the matrix multiplier 101 the inverse matrix computing part 110 obtains (G�GT)-1 (or G-1), which is fed to the matrix multiplier 102.
(8) The matrix multiplier 102 receives GT (or E) from the input terminal 102-1 and feeds GT (G�GT)-1 (or G-1) as output to the matrix multiplier 103.
The filter coefficients can be computed by various successive approximation processes in addition to the above processings (1) to (10). A successive approximation process requires attention to the convergency of the argorithm or the like. However, it is advantageous in view of the amount of computations and amount of memory compared to the above process of directly obtaining the inverse matrix G-1 or minimum norm g-inverse GT (G�GT)-1.
H(q+1)=H(q)+&#945;(q)�R-GT �(G�H(q)) (29)
This means that the desired impulse response vector Ri is 180�-out of phase relative to the phase of the m impulse response vectors Ri (i=1, 2, . . . , m) from the loudspeaker 9 to the microphones 111 to 11m. In other words, what is inverse in phase to the impulse response vectors Ri is obtained through this processing.
FIG. 16 shows a further embodiment of the invention, in which an inverse control is effected on the output of a linear FIR system 40. A desired signal source 11, which radiates a signal to be received, and noise sources 12 to 1m are disposed at respective m input points in a room sound field. Microphones 111 to 11n are disposed at n output points. The output signals u1 (t) to un (t) of the microphones 111 to 11n are converted through A/D converters 301 to 30n into discrete signals u1 (k) to un (k) (k is an integer index) which are fed to FIR filters 211 to 21n. The outputs of the FIR filters 211 to 21n are added together in an adder 27 to obtain an output y(k). In a waveform memory 60 are stored m�n impulse response vectors Gij (i=1, 2, . . . m, j=1, 2, . . . n) of the signal transmission channels between the loudspeakers 11 to 1m and microphones 111 to 11n. In a desired waveform memory 61 are stored desired impulse response vectors Ri with respect to the signal transmission channels between the loudspeakers 11 to 1m and the output of the adder 27. The impulse response vectors and desired impulse response vectors stored in the waveform memory 60 and desired waveform memory 61, respectively, are fed to an operation setting part 80 in a coefficients setting part 300. Similar processings to those (1) to (5) in the Embodiment 1 are then effected in the operation setting part 80 to produce desired impulse response vectors R and matrices G and GT (or unit matrix E) which are supplied to a filter coefficients determining part 100. The filter coefficients determining part 100 includes a matrix operating part 160 and a coefficients distributing part 120. The matrix operating part 160 may be identical to the portion of the filter coefficients determining part 100 shown in FIG. 9 other than the coefficients distributing part 120, and it sets the filter coefficients of the FIR filters 211 to 21n in the manner as described above. It is possible to use the recursive filter coefficients determining part 130 shown in FIG. 11 in lieu of the filter coefficients determining part 100. In this case, by setting the desired vectors R to be ##EQU23## the output y(k) of the adder 27 can be made to consist of the sole intended signal not influenced by any noise from the noise sources 12 to 1m.
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