Veripos ld7, Руководство по эксплуатации

Страница: 59 / 62

Manual Title: LD7 Operations Manual
Ref.: AB-V-MA-00555
Rev No:
A9 Page 59
Receiver Heading calibration methods
Typical accuracy will be (With heading mode fixed) :-

1m separation , expected heading accuracy to be better than 0.3 deg with RTK fixed
quality

3m separation , expected heading accuracy to be better than 0.1 deg with RTK fixed
quality

At 10m separation , expected heading accuracy to be better than 0.03 deg with RTK
fixed quality
The NMEA HDT output string is the Azimuth from Main to Aux antenna direction.
If both the antennas cannot be setup directly on the vessel heading line, a standard gyro calibration
can be carried out
on vessel’s bow and stern centreline position by land survey method to derive the
Computed minus Observe (C-O) corrections.
If both the antenna X, Y are measured accurately relative to the vessel centreline (within a few cm),
you can compute the C-O or biased angle based on arc Tan ((Xm-Xa)/(Ym-Ya)) where m=main and
a=aux antenna X and Y value.
The quickest way to derive the C-O
is to line up the GNSS heading unit to the ship’s heading (ship’s
gyro reading minus GNSS HDT). If accuracy is OK to few degrees for purely positioning purposes
e.g. for general barge moves, setting for anchor handling tug etc.
Below are two examples for deriving the C-O or biased angle corrections for the IMU HDT heading -
1) Where antennas parallel to vessel centre line
1) Where antennas parallel / close to vessel centre line