hey mate,
Gyro wander divides into 2 types.Real wander and apparent wander.
Real wander is any physical deviation of the the gyro axis from a fixed direction in space. Due to diff.forces acting on it (friction of gimbals,spin axis,turbulence...) the errors in precessing rate will slow down or accelerate the rotor of the gyro.
Apparent wander states that NO physical movement in gyro itself takes place.It appears to an observer that there has been a change in direction due to movement of earth rotation.Be
aware that the gyro still maintains its direction with reference to space as we rotate with the earth!Therefor "apparent "wander.
The formula for Total Drift (TD) =
TD=RW + LN + ER + TW
RW= Real wander , LN= Latitude nut
ER= Earth rotation , TW=Transport wander (watch out for TW east or west depending on Northern or Southern Hemisphere)
The LN only compensates if stationary on the Ground at the Latitude to which it is set up for!
Purpose:compensates for apparent wander by making the gyro process in the horizontal plane about the vertical axis.
If working on example this may help:
Northern Hem. / Southern Hem.
ER - / +
LN + / -
TW east - / +
TW west + / -
TW can also be calculatet:G/S * tan. latitude
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6o
hope this helps,greets andi
