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Subject: Is this quite the thing or not?
From: Dan Allen (danallen46@XXX.XXX)
Date: Tue Nov 05 2002 - 14:30:02 EST
Simrad has a new product with two GPS receivers in one instrument for
added redundancy. Of course if the GPS system goes down this
redundancy does nothing for you.
Anyway, here is their simple description of the device: what does the
group think of it? Are their claims justified? Does anyone know what
it is doing -- the carrier phase data? In the spirit of having
multiple ways of tracking your position (GPS, dead reckoning, celestial
nav), it may be a big step backwards as it claims to replace a
gyrocompass. It is this aspect that I am particularly interested in.
--- From the Simrad website: ---
The HS50 replaces several vessel instruments, such as a gyrocompass,
GPS navigator and speed log in one compact navigation package. In
addition the HS50 provides added position redundancy with two complete
GPS receivers.
Precision heading is derived from the fixed-distance dual GPS antenna
arrangement in the Sensor Unit, using carrier phase data to generate
heading information independent of latitude and vessel dynamics. GPS
position and velocity are calculated from both of the two antennas,
which gives total redundant position and velocity sources in this
product.
DGPS signals may be input to the HS50 to improve position and velocity
accuracy. The inertial rate element provides yaw information. In case
of short GPS outages, the inertial rate sensor automatically takes over
as the prime source for heading determination until the GPS comes back
on line. The rate element and GPS’ are working together seamlessly to
insure accurate, continuous and robust heading information even when
the vessel is sitting still.
---See http://www.simrad.com/ for more details.
Dan Allen
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