Vaisala IRIS - Aircraft Tail Radars

A
⋅
−1
=
A
⋅
11
−1
A
⋅
12
−1
A
⋅
13
−1
A
⋅
21
−1
A
⋅
22
−1
A
⋅
23
−1
A
⋅
31
−1
A
⋅
32
−1
A
⋅
33
−1
where:
A
⋅
11
−1
= −
P
⋅
sinPcosθ −
θ
⋅
cos Psin θ
A
⋅
21
−1
= −
P
⋅
sinPcosθ −
θ
⋅
cos Pcos θ
A
⋅
31
−1
= −
P
⋅
cos
These equations show that the motion of the antenna can be expressed as a translational
motion of a reference point (either at the INU or at the ship center of rotation), plus a
rotational motion about a moment arm from the reference point to the antenna.
The translational motion of the reference point is:
As sensed by the INU for the INU Case:
y
⋅
I
=
u
v
w
As sensed by the GPS for the Gyro Case: y
⋅
S
=
u
v
w
As a special case, if the INU and antenna are located at precisely the same position, then,
INU Case:
Δy′
AI
= 0
so that
y
A
⋅
= y
I
⋅
In this case, the antenna velocity is equal to the INU velocity since the moment arm is 0
length.
B.1.3
Aircraft Tail Radars
For aircraft tail radars, the math for the velocity correction is dierent.
Appendix B – Radial Velocity Correction
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