Gps Check - Raymarine a65 Operation Instructions Manual

14.4 GPS Check

Checking GPS operation
You can check that the GPS is functioning correctly
using the chart application.
From the Homescreen:
1. Select the Chart application.
2. Check the screen.
You should see:
Your boat position (this indicates a GPS fix).
Your current position is represented by a boat
symbol or solid circle. Your position is also
displayed in the data bar under VES POS.
A solid circle on the chart indicates that neither
heading nor Course Over Ground (COG) data
is available.
Note: Raymarine recommends that you check the
displayed vessel position in the Chart application
against your actual proximity to a known charted
object. GPS / GNSS receivers typically have an
accuracy of between 5 and 15 m.
Note: A GPS Status page is available from the
GPS Set-up menu: (Homescreen > Set-up >
System Settings > GPS Set-up > View Satellites
Status). This provides HDOP and EHPE data
which can provide an indication of how accurate
your vessel's GPS position is.
GNSS Status
The GPS status page enables you to view the status
of the available satellites that are compatible with
your receiver.
The satellite constellations are used to position your
vessel in the Chart and Weather applications. You
can set up your receiver and check its status from
the GPS Set-up menu: Homescreen > Set-up >
System Settings > GPS Set-up. For each satellite,
the screen provides the following information:
1
160
1. Sky view
2. Satellite status
3. Position and fix information
Sky view
Sky view is a visual representation that shows
the position of navigation satellites and their type.
Satellite types are:
• Circle — A circle identifies a satellite from the
GPS constellation.
• * Diamond — A diamond identifies a satellite from
the GLONASS constellation.
• Square — A square identifies an (SBAS)
differential satellite.
Note: * GLONASS satellites are only available
when connected to a compatible GNSS receiver.
Refer to the Technical specification for your
product to identify your receiver type.
Satellite status area
The Satellite status area displays the following
information about each satellite:
• Type — Identifies which constellation the satellite
belongs to.
• ID — Displays the satellites identification number.
• CNO (Carrier-to-noise ratio) — Displays the signal
strength of each satellite shown in the Sky view:
– Grey = searching for satellite
– Green = satellite in use
– Orange = tracking satellite
• Azimuth and Elevation — Provides the angle of
elevation and azimuth between the location of the
receiver and the satellite.
Position and fix information
The following positional and fix information is
provided:
• Horizontal Dilution of Precision (HDOP)
— HDOP is a measure of satellite navigation
accuracy, calculated from a number of factors
including satellite geometry, system errors in
the data transmission and system errors in the
receiver. A higher figure signifies a greater
positional error. A typical receiver has an accuracy
of between 5 and 15 m. As an example, assuming
a receiver error of 5 m, an HDOP of 2 would
represent an error of approximately 15 m. Please
remember that even a very low HDOP figure is
NO guarantee that your receiver is providing an
accurate position. If in doubt, check the displayed
vessel position in the Chart application against
2
your actual proximity to a known charted object.
• Estimated Horizontal Position Error (EHPE)
— EHPE is a measure of the estimated error of
a position fix in the horizontal plane. The value
displayed indicates that your position is within a
3
circle radius of the stated size 50% of the time.
• Fix status — indicates the actual mode the
receiver is reporting:
D13122-1
LightHouse MFD operation instructions