Passive channel calibration method based on non-linear antenna array
View Patent ↗Taught herein is a passive channel calibration method wherein a non-linear antenna array sets an antenna array to a non-linear formation that contains at least a combination of translation invariant dual array-element couples, detects single-azimuth ocean echoes via combinations of translation invariant dual array-element couples, estimates channel amplitude mismatch coefficients via the single-azimuth ocean echoes to implement amplitude calibration, and estimates channel phase mismatch coefficients via the single-azimuth ocean echoes after amplitude calibration and the known array position information to implement phase calibration.
1. A passive channel calibration method based on a non-linear antenna array, comprising:
setting an antenna array to a non-linear formation that contains at least a combination of translation invariant dual array-element couples;
detecting single-azimuth ocean echoes via said combinations of translation invariant dual array-element couples;
estimating channel amplitude mismatch coefficients via said single-azimuth ocean echoes to implement amplitude calibration; and
estimating channel phase mismatch coefficients via said single-azimuth ocean echoes after said amplitude calibration and the known array position information to implement phase calibration.
2. A passive channel calibration method based on a non-linear antenna array, comprising:
setting an antenna array to a non-linear formation that contains at least a combination of translation invariant dual array-element couples;
detecting single-azimuth ocean echoes via said combinations of translation invariant dual array-element couples;
estimating channel amplitude mismatch coefficients via said single-azimuth ocean echoes to implement amplitude calibration; and
estimating channel phase mismatch coefficients via said single-azimuth ocean echoes after said amplitude calibration and the known array position information to implement phase calibration, wherein
said channel amplitude mismatch coefficients are estimated by said single-azimuth ocean echoes using the equation
g
^
i
=
1
L
∑
l
=
1
L
Y
i
(
l
)
2
Y
1
(
l
)
2
to implement said amplitude calibration,
ĝ i , is an estimated value of the channel amplitude mismatch coefficient of array element i;
i=1, 2, . . . , M;
M is a number of array elements;
Y i (l) is an output of the lth single-azimuth echo received by said array element i;
I=1, 2. . . L, and
L is a number of said single-azimuth echoes.
3. A passive channel calibration method based on a non-linear antenna array, comprising:
setting an antenna array to a non-linear formation that contains at least a combination of translation invariant dual array-element couples;
detecting single-azimuth ocean echoes via said combinations of translation invariant dual array-element couples;
estimating channel amplitude mismatch coefficients via said single-azimuth ocean echoes to implement amplitude calibration; and
estimating channel phase mismatch coefficients via said single-azimuth ocean echoes after said amplitude calibration and the known array position information to implement phase calibration, wherein
said channel amplitude mismatch coefficients are estimated by said single-azimuth ocean echoes using a equation
g
^
i
=
1
L
∑
l
-
1
L
Y
i
(
l
)
2
Y
1
(
l
)
2
to implement amplitude Calibration;
ĝ i is an estimated value of the channel amplitude mismatch coefficient of array element i;
i=1, 2, . . . , M;
M is a number of array elements;
Y i (l) being the output of the lth single-azimuth echo received by said array element i,
l=1, 2, . . . , L, and
L is a number of said single-azimuth echoes.
4. A passive channel calibration method based on a non-linear antenna array, comprising:
setting an antenna array to a non-linear formation that contains at least a combination of translation invariant dual array-element couples;
detecting simile-azimuth ocean echoes via said combinations of translation invariant dual array-element couples;
estimating channel amplitude mismatch coefficients via said single-azimuth ocean echoes to implement amplitude calibration; and
estimating channel phase mismatch coefficients via said simile-azimuth ocean echoes after said amplitude calibration and the known array position information to implement phase calibration, wherein
said channel amplitude mismatch coefficients are estimated by said single-azimuth ocean echoes using a equation
g
^
i
=
∑
l
=
1
L
Y
i
(
l
)
/
∑
l
=
1
L
Y
1
(
l
)
to implement amplitude calibration;
ĝ i is an estimated value of the channel amplitude mismatch coefficient of array element i;
i=1, 2, . . . , M;
M is a number of array elements;
Y i (l) is the output of the lth single-azimuth echo received by said array element i,
l=1, 2, . . . , L, and
L is a number of said single-azimuth echoes.
5. A passive channel calibration method based on a non-linear antenna array, comprising:
setting an antenna array to a non-linear formation that contains at least a combination of translation invariant dual array-element couples;
detecting single-azimuth ocean echoes via said combinations of translation invariant dual array-element couples;
estimating channel amplitude mismatch coefficients via said single-azimuth ocean echoes to implement amplitude calibration; and
estimating channel phase mismatch coefficients via said single-azimuth ocean echoes after said amplitude calibration and the known array position information to implement phase calibration, wherein
said channel amplitude mismatch coefficients are estimated by said single-azimuth ocean echoes using a equation
g
^
i
=
∑
l
=
1
L
Y
i
(
l
)
/
∑
l
=
1
L
Y
1
(
l
)
to implement amplitude calibration;
ĝ i is an estimated value of the channel amplitude mismatch coefficient of array element i,
i=1, 2, . . ., M;
M is a number of array elements;
Y i (l) is the output of the lth single-azimuth echo received by said array element i,
l=1, 2, . . . L, and
L is a number of said single-azimuth echoes.
6. The method of claim 5 , wherein
said channel phase mismatch coefficients are estimated by said single-azimuth ocean echoes after said amplitude calibration and the known array position information from
Ψ
^
=
arg
min
Ψ
Y
-
f
′
(
Ψ
)
2
to implement phase calibration;
Ψ
=
[
θ
1
,
θ
2
,
⋯
,
θ
L
,
ϕ
2
,
ϕ
3
,
⋯
,
ϕ
M
]
T
;
Y
=
[
Y
2
Y
3
⋮
Y
M
]
;
Y
i
=
[
Y
i
(
1
)
,
Y
i
(
2
)
,
⋯
,
Y
i
(
L
)
]
T
;
f
′
(
Ψ
)
=
[
f
2
′
(
Ψ
)
f
3
′
(
Ψ
)
⋮
f
M
′
(
Ψ
)
]
;
f
i
′
(
Ψ
)
=
[
Y
1
(
1
)
ⅇ
j
[
2
π
λ
(
x
i
sin
θ
1
+
y
i
cos
θ
1
)
+
ϕ
i
]
,
Y
1
(
2
)
ⅇ
j
[
2
π
λ
(
x
i
sin
θ
2
+
y
i
cos
θ
2
)
+
ϕ
i
]
,
⋯
,
Y
1
(
L
)
ⅇ
j
[
2
π
λ
(
x
i
sin
θ
L
+
y
i
cos
θ
L
)
+
ϕ
i
]
]
T
θ l is the arrival angle of the lth single-azimuth echo;
Φ i is the channel phase mismatch coefficient of array element i;
(x i , y i ) is the array element position coordinates, and array element 1 is the origin of coordinates, i.e., (x 1 , y 1 )=(0,0);
λ is the echo signal wavelength; and
{circumflex over (Ψ)} is the estimated value of Ψ.
7. The method of claim 6 , wherein
three array elements are selected from all array elements to form a triangular array;
said triangular array is utilized by the processes to decrease the dimension number of global optimization; and
said channel phase mismatch coefficients are estimated via pre-estimation of initial values and local optimization methods.
8. The method of claim 5 , wherein
said channel phase mismatch coefficients are estimated by said single-azimuth ocean echoes after said amplitude calibration and the known array position information from
Ψ
^
=
arg
min
Ψ
Y
-
f
~
(
Ψ
)
2
to implement phase calibration;
Ψ
=
[
θ
1
,
θ
2
,
⋯
,
θ
L
,
ϕ
2
,
ϕ
3
,
⋯
,
ϕ
M
]
T
;
Y
=
[
Y
2
Y
3
⋮
Y
M
]
;
Y
i
=
[
Y
i
(
1
)
,
Y
i
(
2
)
,
⋯
,
Y
i
(
L
)
]
T
;
f
~
(
Ψ
)
=
[
f
~
2
(
Ψ
)
f
~
3
(
Ψ
)
⋮
f
~
M
(
Ψ
)
]
;
f
~
i
(
Ψ
)
=
[
A
^
(
1
)
ⅇ
j
[
2
π
λ
(
x
i
sin
θ
1
+
y
i
cos
θ
1
)
+
ϕ
i
]
,
A
^
(
2
)
ⅇ
j
[
2
π
λ
(
x
i
sin
θ
2
+
y
i
cos
θ
2
)
+
ϕ
i
]
,
…
,
A
^
(
L
)
ⅇ
j
[
2
π
λ
(
x
i
sin
θ
L
+
y
i
cos
θ
L
)
+
ϕ
i
]
]
T
;
A
^
(
l
)
=
1
M
∑
i
=
1
M
Y
i
(
l
)
ⅇ
-
j
[
2
π
λ
(
x
i
sin
θ
l
+
y
i
cos
θ
l
)
+
ϕ
i
]
=
1
M
{
∑
i
=
2
M
Y
i
(
l
)
ⅇ
-
j
[
2
π
λ
(
x
i
sin
θ
l
+
y
i
cos
θ
l
)
+
ϕ
i
]
+
Y
1
(
l
)
}
;
θ l is the arrival angle of the lth single-azimuth echo;
Φ i is the channel phase mismatch coefficient of array element i;
(x i , y i ) is the array element position coordinates, and array element 1 is the origin of coordinates, i.e., (x 1 , y 1 )=(0,0);
λ is the echo signal wavelength; and
{circumflex over (Ψ)} is the estimated value of Ψ.
9. The method of claim 8 , wherein
three array elements are selected from all array elements to form a triangular array;
said triangular array is utilized by the processes to decrease the dimension number of global optimization; and
said channel phase mismatch coefficients are estimated via pre-estimation of initial values and local optimization methods.
10. The method of claim 9 , comprising
1) selecting three array elements to form a triangular array, along with three single-azimuth echoes for parameter estimation;
2) choosing any element of said triangular array as a reference channel and estimating the phase mismatch coefficients of other two channels and the arrival angles of three single-azimuth echoes via global optimization methods;
3) adding a single-azimuth echo for parameter estimation of said triangular array, and thus obtaining its arrival angle;
4) obtaining arrival angles of other single-azimuth echoes according to step 3);
5) combining said triangular array with another array element to form a 4-element array, and using all single-azimuth echoes for parameter estimation of said 4-element array, so as to obtain the channel phase mismatch coefficient of the newly-added array element; and
6) obtaining channel phase mismatch coefficients of other array elements according to step 5).
11. The method of claim 10 , wherein after step 4) and before step 5), using all said single-azimuth echoes for parameter estimation of said triangular array, and regarding the obtained estimated values of said arrival angles of said single-azimuth echoes and said channel phase mismatch coefficients as initial values, obtaining more accurately estimated values of these parameters via said local optimization methods.
12. The method of claim 10 , wherein after step 6), using all said single-azimuth echoes for parameter estimation of the whole array, and regarding the obtained estimated values of said arrival angles of said single-azimuth echoes and said channel phase mismatch coefficients as initial values, obtaining more accurately estimated values of these parameters via said local optimization methods.
13. The method of claim 10 , wherein for an M-element L-form array, array element 1, 2 and M are used for parameter estimation as a triangular array selected in step 1), so as to implement channel phase calibration.
14. The method of claim 10 , wherein for a 4-element L-form array, array element 1, 2, 4 or array element 2, 3, 4 are used for parameter estimation as a triangular array selected in step 1), so as to implement channel phase calibration.
15. The method of claim 10 , wherein for a 4-element rectangular array, any three array elements are used for parameter estimation as a triangular array selected in step 1), so as to implement channel phase calibration.
16. The method of claim 1 , comprising
said estimating channel amplitude mismatch coefficients via single-azimuth ocean echoes having unknown direction to implement amplitude calibration; and
said estimating channel phase mismatch coefficients via said single-azimuth ocean echoes having unknown direction after said amplitude calibration and the known array position information to implement phase calibration.
17. The method of claim 1 , wherein said single-azimuth ocean echoes have unknown direction.
18. The method of claim 1 , wherein said non-linear formation of said antenna array comprises unconnected elements that do not lie on a straight line.
19. The method of claim 1 , wherein said estimating channel phase mismatch coefficients does not comprise using any auxiliary signal sources.
20. The method of claim 19 , wherein said method is a passive channel calibration method comprising direct estimation of channel phase mismatch coefficients from measured data and array format information.