FLIR RAYMARINE E125 - GPS Check; Checking GPS Operation; GNSS Status

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
x). 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. Sky view
2. Satellite status
3. Position and x 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 identies a satellite from the
GPS constellation.
• * Diamond — A diamond identies a satellite from
the GLONASS constellation.
• Square — A square identies an (SBAS)
differential satellite.
Note: * GLONASS satellites are only available
when connected to a compatible GNSS receiver.
Refer to the Technical specication for your
product to identify your receiver type.
Satellite status area
The Satellite status area displays the following
information about each satellite:
• Type — Identies which constellation the satellite
belongs to.
• ID — Displays the satellites identication 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 x information
The following positional and x 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 gure signies 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 gure is
NO guarantee that your receiver is providing an
accurate position. If in doubt, check the displayed
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