Receiver and adaptive digital notch filter

Claim 2

A receiver comprising: first means for producing a digital baseband signal x(n) and second means for (i) filtering out narrowband interference corrupting x(n) and (ii) producing an output y(n), said second means comprising an adaptive digital notch filter connected for receiving x(n) and having z-transform transfer function H(z), said H(z)=(1+k.sup.* z.sup.-1)/(1+a.sup.* z.sup.-1) where a * =Bk * * is the complex conjugate operator B is a selected multiplier less than 1 k=(k R )/(W) k R =-C(n)/D(n) C(n)=GC(n-1)+P(n-1)P * (n) D(n)=GD(n-1)+P(n-1)P * (n-1) ##EQU2## and G is a selected multiplier less than 1 and W is a predetermined one of (I) |k R | or (II) a predetermined constant said a * and k * being iteratively computed and settling at substantially steady state values when the narrowband interference in y(n) is minimized.

Claim 3

A receiver as defined in claim 1 wherein W is equal to |k R |.

Claim 4

A receiver as defined in claim 2 wherein G is in the range of 0.5 to 0.99.

Claim 5

A receiver as defined in claim 3 wherein B is in the range of 0.6 to 0.99.

Claim 6

A receiver as defined in claim 4 wherein x(n) has quadrature components.

Claim 7

A receiver as defined in claim 1 wherein G is in the range of 0.5 to 0.99.

Claim 8

A receiver as defined in claim 1 wherein G is in the range of 0.85 to 0.99.

Claim 9

A receiver as defined in claim 2 wherein G is fixed at a value of approximately 0.95.

Claim 10

A receiver as defined in claim 1 wherein B is in the range of 0.6 to 0.99.

Claim 11

A receiver as defined in claim 1 wherein B is fixed at a value of approximately 0.9.

Claim 12

A receiver as defined in claim 1 wherein B is fixed at a value of approximately 0.9 and G is fixed at a value of approximately 0.95.

Claim 13

A receiver comprising: first means producing a digital baseband signal x 1 (n), and second means for (i) filtering out a plurality of at least j of narrowband interferences corrupting x 1 (n) and (ii) producing an output y j (n), said second means comprising a plurality j of adaptive digital notch filters connected in cascade so that the first filter receives x 1 (n) and outputs y 1 (n), and the jth filter receives x j (n)=y j-1 (n) and outputs y j (n), said j filters each having a z-transform transfer function H i (z), said H.sub.i (z)=(1+k.sub.i.sup.* z.sup.-1)/(1+a.sub.i.sup.* z.sup.-1) where i=1 . . . j a i * =B i k i * * is the complex conjugate operator B i is a selected multiplier less than 1 k i =(k Ri )/(W i ) k Ri =-C i (n)/D i (n) C i (n)=G i C i (n-1)+P i (n-1)P i * (n) Di(n)=G i D i (n-1)+P i (n-1)P i * (n-1) ##EQU3## and G i is a selected multiplier less than 1 and W i is a predetermined one of (I) |k Ri | or (II) a predetermined constant q i each said a i * and k i * being iteratively computed and settling at substantially steady state values when one of the narrowband interferences in y i (n) is minimized.

Claim 14

A receiver comprising: first means producing a digital baseband signal x 1 (n), and second means for (i) filtering out a plurality of at least j of narrowband interferences corrupting x 1 (n) and (ii) producing an output y j (n), said second means comprising a plurality j of adaptive digital notch filters connected in cascade so that the first filter receives x 1 (n) and outputs y 1 (n), and the jth filter receives x j (n)=y j-1 (n) and outputs y j (n), said j filters each having a z-transform transfer function H i (z), said H.sub.i (z)=(1+k.sub.i.sup.* z.sup.-1)/(1+a.sub.i.sup.* z.sup.-1) where i=1 . . . j a i * =B i k i * * is the complex conjugate operator B i is a selected multiplier less than 1 k i =(k Ri )/(W i ) k Ri =-C i (n)/D i (n) C i (n)=G i C i (n-1)+P i (n-1)P i * (n) Di(n)=G i D i (n-1)+P i (n-1)P i * (n-1) ##EQU3## and G i is a selected multiplier less than 1 and W i is a predetermined one of (I) |k Ri | or (II) a predetermined constant q i each said a i * and k i * being iteratively computed and settling at substantially steady state values when one of the narrowband interferences in y i (n) is minimized.

Claim 15

A receiver as defined in claim 12 wherein W i is equal to |k Ri |.

Claim 16

A receiver as defined in claim 13 wherein each G i is in the range of 0.5 to 0.99.

Claim 17

A receiver as defined in claim 13 wherein each G i is in the range of 0.85 to 0.99.

Claim 18

A receiver as defined in claim 13 wherein each G i is fixed in value and each G i has a value of approximately 0.95.

Claim 19

A receiver as defined in claim 13 wherein each B i is fixed in value and each has a value of approximately 0.9, and each G i is fixed in value and each has a value of approximately 0.95.

Claim 20

A receiver as defined in claim 14 wherein each B i is in the range of 0.6 to 0.99.

Claim 21

A receiver as defined in claim 14 wherein each B i is fixed in value and each B i has a value of approximately 0.9.

Claim 22

An adaptive digital notch filter for use in (i) filtering a digital signal x(n) corrupted with interference, and (ii) providing digital signal output y(n) where the corrupting interference has been reduced, said filter having a z-transform transform function H(z), said H(z)=(1+k.sup.* z.sup.-1)/(1+a.sup.* z.sup.-1) where a * =Bk * * is the complex conjugate operator B is a selected multiplier less than 1 k=(k R )/(W) k R =-C(n)/D(n) C(n)=GC(n-1)+P(n-1)P * (n) D(n)=GD(n-1)+P(n-1)P * (n-1) ##EQU4## and G is a selected multiplier less than 1 and W is a predetermined one of (I) |k R | or (II) a predetermined constant said a * and k * being iteratively computed at new input samples and settling at substantially steady state values when the interference in y(n) is minimized.

Claim 23

An adaptive digital notch filter for use in (i) filtering a digital signal x(n) corrupted with interference, and (ii) providing digital signal output y(n) where the corrupting interference has been reduced, said filter having a z-transform transform function H(z), said H(z)=(1+k.sup.* z.sup.-1)/(1+a.sup.* z.sup.-1) where a * =Bk * * is the complex conjugate operator B is a selected multiplier less than 1 k=(k R )/(W) k R =-C(n)/D(n) C(n)=GC(n-1)+P(n-1)P * (n) D(n)=GD(n-1)+P(n-1)P * (n-1) ##EQU4## and G is a selected multiplier less than 1 and W is a predetermined one of (I) |k R | or (II) a predetermined constant said a * and k * being iteratively computed at new input samples and settling at substantially steady state values when the interference in y(n) is minimized.

Claim 24

A filter as defined in claim 20 wherein W is equal to |k R |.

Claim 25

A filter as defined in claim 21 wherein B is in the range of 0.6 to 0.99, and G is in the range of 0.5 to 0.99.

Claim 26

A filter as defined in claim 22 wherein B is fixed at a value less than its maximum when G is simultaneously fixed at a value near its maximum.

Claim 27

A filter as defined in claim 23 where B is approximately 0.9 and G is simultaneously approximately 0.95.

Claim 28

A filter as defined in claim 22 wherein G is fixed at value less than its maximum when B is simultaneously fixed at a value near its maximum.