ComNav Vector G2/G2B Installation & Operation Operation
Document PN 29010078 V2.0 - 45 -
DRAFT #3 – 29 May 2009
Normal Operation
Once the Vector G2 has successfully acquired a sufficient number of GPS signals, of
high enough quality, it begins to generate navigational data – position, heading, speed
and so on.
It’s up to you what you do with that data, of course!
The G2 is configured at the factory with a specific set of output data settings … enabled
output data “sentences”, update rates and Baud rates. All those are described in this
section.
The suggested standard wiring diagrams (see Figure
12, Figure 14 and Figure 15) are
based on that factory-default output configuration. But you may change the G2’s
configuration as required, and even wire it differently than shown in the standard
diagrams.
Output Ports
Typically, the user of a G2 wants it to output certain navigational data, updated at rates
that are suitable for the other equipment connected to the G2, and for what the overall
“navigation” system is supposed to be doing.
As well, the “bit rate” (i.e., Baud rate) at which the G2’s two output ports are transmitting
data (& receiving data, if necessary) must match the device(s) to which each is
connected.
The G2’s two output ports – Port A and Port B – allow for two different sets of navigation
data to be output from the G2. Each port can be configured with its own combination of
enabled output data sentences, sentence update rates, and Baud rate.
• For example: when a ComNav autopilot is being used with the G2, heading and
speed from the G2 are needed by the autopilot, in order for it to be able to steer
the vessel safely on the course that the user wants to follow.
– All ComNav autopilots need heading to be updated at a rate of about 10 Hz
or more; any slower causes the autopilot’s steering control algorithm to
respond too slowly to changes in the vessel’s actual heading (from wind,
waves, current, etc.).
– Speed is only needed at 1 Hz (or less), since it is not used in the steering
algorithm, but only to select which set of steering parameters is being used
by the autopilot.
– Baud rate is always 4800.
• When used with other types of equipment – e.g., a Chartplotter, a Navigation
program on a PC, a Radar set – typically there is other information needed:
position, course over ground, time & date, the GPS satellites’ status and so on.
Update rates required are usually slow – 1 Hz or less.
As mentioned previously, the G2 is configured at the factory for easy use in typical
marine situations, such as illustrated in Figure
1.
• On Port A is a set of sentences for “general-purpose marine Navigation use”,
which collectively provides the following information:
– Position, course & speed over ground, time & date, True & Magnetic
heading, rate of turn, and GPS satellite status (all at 1 Hz or less).
• On Port B are sentences for “autopilot use”:
– True & Magnetic heading (at 10 Hz), and speed (at 1 Hz).
• Both ports are at 4800 Baud.
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