System for self-localizing near field data processing
View Patent ↗A system, processor and method of use for calibration processing is provided to calibrate acoustic vector sensor data collected at comparatively close range. Vector sensor data collected at close range includes data collected with source-to-receiver separations ranging from a one-tenth to approximately two acoustic wavelengths. The calculations substantially account for the acoustic impedance of a spherically diverging wave front, where the curvature is sufficiently pronounced to cause errors in resulting measurements in the calculations. The processing uses information contained within the vector sensor data to increase the accuracy of the vector sensor data.
1. A system for self-localizing acoustic sensors, said system comprising:
an acoustic source positionable to generate an acoustic signal;
a reference hydrophone positionable to have a source-to-reference distance along a first direction, and positionable to sample the acoustic signal to produce a reference sample set of collected data;
a first acoustic sensor positionable to a first source-to-sensor distance along a second direction different from the first direction, and positionable to sample the acoustic signal to produce a first sensor sample set of collected data; and
a processor positionable to determine a range difference error in response to a comparison of the reference sample set of collected data and the first sensor sample set of collected data, and positionable to correct at least partially an estimated range of the first source-to-sensor distance in response to the range difference error;
wherein a first portion of the range difference error is used to correct the estimated range of the first source-to-sensor distance and a second portion of the range difference error is used to correct the source-to-reference distance.
2. A system for self-localizing acoustic sensors, said system comprising:
an acoustic source positionable to generate an acoustic signal;
a reference hydrophone positionable to have a source-to-reference distance along a first direction, and positionable to sample the acoustic signal to produce a reference sample set of collected data;
a first acoustic sensor positionable to a first source-to-sensor distance along a second direction different from the first direction, and positionable to sample the acoustic signal to produce a first sensor sample set of collected data; and
a processor positionable to determine a range difference error in response to a comparison of the reference sample set of collected data and the first sensor sample set of collected data, and positionable to correct at least partially an estimated range of the first source-to-sensor distance in response to the range difference error;
wherein the first source-to-sensor distance is corrected using a complex pressure sensitivity determined in accordance with the equation
M
uut
0
=
M
ref
v
uut
0
v
ref
r
uut
+
η
δ
r
r
ref
+
(
η
-
1
)
δ
r
ⅇ
j
k
(
r
uut
-
r
ref
-
δ
r
)
where M uut 0 is the complex sensitivity of the first acoustic sensor, M ref is the complex sensitivity of the reference hydrophone, v uut 0 is the complex voltage measured on the first acoustic sensor, v ref is the complex voltage measured on the reference hydrophone, k is the wave number, r uut is the first source-to-sensor distance, r ref is the source-to-reference distance, and δr is the range difference error.
3. A system for self-localizing acoustic sensors, said system comprising:
an acoustic source positionable to generate an acoustic signal;
a reference hydrophone positionable to have a source-to-reference distance along a first direction, and positionable to sample the acoustic signal to produce a reference sample set of collected data;
a first acoustic sensor positionable to a first source-to-sensor distance along a second direction different from the first direction, and positionable to sample the acoustic signal to produce a first sensor sample set of collected data; and
a processor positionable to determine a range difference error in response to a comparison of the reference sample set of collected data and the first sensor sample set of collected data, and positionable to correct at least partially an estimated range of the first source-to-sensor distance in response to the range difference error;
wherein the first source-to-sensor distance is corrected using a complex acceleration sensitivity determined in accordance with the equation
M
uut
1
=
M
ref
v
uut
1
v
ref
r
uut
+
η
δ
r
r
ref
+
(
η
-
1
)
δ
r
ρ
k
(
k
(
r
uut
+
η
δ
r
)
1
+
j
k
(
r
uut
+
η
δ
r
)
)
ⅇ
j
k
(
r
uut
-
r
ref
-
δ
r
)
where M uut 1 is the complex sensitivity of the first acoustic sensor, M ref is the complex sensitivity of the reference hydrophone, v uut 1 is the voltage measured on the first acoustic sensor, v ref is the complex voltage measured on the reference hydrophone, r ref is the source-to-reference distance, r out is the first source-to-sensor distance, η is a control parameter that is greater or equal to zero and is less than or equal to one, ρ is the fluid density, k is the wave number, and δr is the range difference error.
4. The system in accordance with claim 3 , wherein the control parameter η is used to selectively apportion a first portion of the range difference error to correct the estimated range of the first source-to-sensor distance and to selectively apportion a second portion of the range difference error to correct the estimated range of the source-to-reference distance.
5. The system in accordance with claim 3 , wherein the range difference error is used to correct a source-to-sensor range that varies due to translation that occurs during rotation of the first acoustic sensor during production of the first sensor sample set of collected data.
6. A processor arranged to receive a reference sample set of collected data from a reference hydrophone arranged having a source-to-reference distance along a first direction wherein the reference sample set of collected data is produced by sampling an acoustic signal generated by an acoustic source, that is arranged to receive a sensor sample set of collected data from an acoustic sensor that is arranged having a source-to-sensor distance along a second direction that is different from the first direction wherein the sensor sample set of collected data is produced by sampling an acoustic signal generated by the acoustic source, is arranged to determine a range difference error in response to a comparison of the reference sample set of collected data and the sensor sample set of collected data, and that is arranged to correct at least partially an estimated range of the source-to-sensor distance in response to the range difference error;
wherein said processor is arranged to correct the source-to-sensor distance using a complex pressure sensitivity determined in accordance with the equation
M
uut
0
=
M
ref
v
uut
0
v
ref
r
uut
+
η
δ
r
r
ref
+
(
η
-
1
)
δ
r
ⅇ
j
k
(
r
uut
-
r
ref
-
δ
r
)
where M uut 0 is the complex sensitivity of the acoustic sensor, M ref is the complex sensitivity of the reference hydrophone, v uut 0 is the complex voltage measured on the acoustic sensor, v ref is the complex voltage measured on the reference hydrophone, k is the wave number, r uut is the source-to-sensor distance, r ref is the source-to-reference distance, and δr is the range difference error.
7. A processor arranged to receive a reference sample set of collected data from a reference hydrophone arranged having a source-to-reference distance along a first direction wherein the reference sample set of collected data is produced by sampling an acoustic signal generated by an acoustic source, that is arranged to receive a sensor sample set of collected data from an acoustic sensor that is arranged having a source-to-sensor distance along a second direction that is different from the first direction wherein the sensor sample set of collected data is produced by sampling an acoustic signal generated by the acoustic source, is arranged to determine a range difference error in response to a comparison of the reference sample set of collected data and the sensor sample set of collected data, and that is arranged to correct at least partially an estimated range of the source-to-sensor distance in response to the range difference error;
wherein said processor is arranged to correct the source-to-sensor distance using a complex acceleration sensitivity determined in accordance with the equation
M
uut
1
=
M
ref
v
uut
1
v
ref
r
uut
+
η
δ
r
r
ref
+
(
η
-
1
)
δ
r
ρ
k
(
k
(
r
uut
+
η
δ
r
)
1
+
j
k
(
r
uut
+
η
δ
r
)
)
ⅇ
j
k
(
r
uut
-
r
ref
-
δ
r
)
where M uut 1 is the complex sensitivity of the acoustic sensor, M ref is the complex sensitivity of the reference hydrophone, v uut 1 is the voltage measured on the acoustic sensor, v ref is the complex voltage measured on the reference hydrophone, r ref is the source-to-reference distance, r uut is the source-to-sensor distance, η is a control parameter that is greater or equal to zero and is less than or equal to one, ρ is the fluid density, k is the wave number, and δr is the range difference error.