User manual

Table Of Contents
hand indicated the positive direction of rotation.) Similarly, TY measures rotation about the x-
axis and is positive when the profiler tips to starboard. (Note that this rotation is consistent with
the "right-hand rule".) The units of tilt are degrees. Full scale for both pitch and roll is ±45°. Tilt
values near zero indicate that the profiler is vertical.
The next three numbers in each ACM scan are HX, HY, and HZ, the three components of
the local magnetic field as measured by the compass. Each component is normalized by the
strength of the magnetic field vector. Thus, for example,
222
hzhyhx
hx
HX
++
=
where hx, hy, and hz are the measured components of magnetic flux along each axis of the
compass. HY and HZ are determined similarly. Note that for the normalized values it is
necessarily true that HX
2
+ HY
2
+ HZ
2
= 1. The normalized values are also, by definition, the
direction cosines of the magnetic field in the frame of the MMP.
By convention the magnetic flux to be maximally positive along an axis of the compass is
defined when the magnetic field vector is parallel to that axis. The magnetic flux is maximally
negative along an axis of the compass when the magnetic field vector is anti-parallel to that axis.
The magnetic flux is zero along an axis of the compass when the magnetic field vector is
perpendicular to that axis. Using this convention see:
ϕ
sin
=
HZ
where φ is the angle of the magnetic field vector measured from the horizontal. φ is positive if
the field vector points above the horizontal and negative if it points below. Also there is:
HHorizontal
HHorizontal
HY
HYHX
HY
HX
HYHX
HX
θ
θ
cos
sin
22
22
==
+
==
+
Appendix D-5