Furuno SC-60 Manuale Utente
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PRINCIPLE OF OPERATION
Own ship's heading can be determined by decoding the data in the carrier
frequency in addition to ordinary GPS parameters. In principle, a pair of two
antennas A1(ref) and A2(fore), each connected with an associated GPS engine
and processor, are installed along the ship's fore-and-aft line. GPS systems at
A1 and A2 calculate the range and azimuth to the satellite. Difference in range
between A1 and A2 is
frequency in addition to ordinary GPS parameters. In principle, a pair of two
antennas A1(ref) and A2(fore), each connected with an associated GPS engine
and processor, are installed along the ship's fore-and-aft line. GPS systems at
A1 and A2 calculate the range and azimuth to the satellite. Difference in range
between A1 and A2 is
∆λ
+ n
λ
where
λ
is 19 cm. “n” is automatically found
during the initialization stage by receiving three satellites. A fraction of a carrier
wavelength,
wavelength,
∆λ
, is processed by FURUNO’s advanced kinematic technology in
geographical survey, thus determining a vector (range and orientation) A1 to A2.
In reality, a third antenna is used to reduce the influence of pitch, roll and yaw,
and five satellites are processed to process 3D data. If the GPS signal is blocked
by a tall building or the vessel is under a bridge, the 3-axis solid-state angular
rate gyros in the processor unit take place of the satellite compass, maintaining
the current heading continuously.
In reality, a third antenna is used to reduce the influence of pitch, roll and yaw,
and five satellites are processed to process 3D data. If the GPS signal is blocked
by a tall building or the vessel is under a bridge, the 3-axis solid-state angular
rate gyros in the processor unit take place of the satellite compass, maintaining
the current heading continuously.
Heading
θ
Antenna A1
Antenna A2
Antenna A3
Difference between the
range from satellite to
antenna 1 and the range
to antenna 2.
range from satellite to
antenna 1 and the range
to antenna 2.
n
λ
∆λ
λ
Fore-
an
d-aft
line
Vector
to
decid
e
heading
Principle of satellite compass operation