14.4 GPS CheckChecking GPS operationYou can check that the GPS is functioning correctlyusing 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 boatsymbol or solid circle. Your position is alsodisplayed in the data bar under VES POS.A solid circle on the chart indicates that neitherheading nor Course Over Ground (COG) datais available.Note: Raymarine recommends that you check thedisplayed vessel position in the Chart applicationagainst your actual proximity to a known chartedobject. GPS / GNSS receivers typically have anaccuracy of between 5 and 15 m.Note: A GPS Status page is available from theGPS Set-up menu: (Homescreen > Set-up >System Settings > GPS Set-up > View SatellitesStatus). This provides HDOP and EHPE datawhich can provide an indication of how accurateyour vessel’s GPS position is.GNSS StatusThe GPS status page enables you to view the statusof the available satellites that are compatible withyour receiver.The satellite constellations are used to position yourvessel in the Chart and Weather applications. Youcan set up your receiver and check its status fromthe GPS Set-up menu: Homescreen > Set-up >System Settings > GPS Set-up. For each satellite,the screen provides the following information:123D13122-11. Sky view2. Satellite status3. Position and fix informationSky viewSky view is a visual representation that showsthe position of navigation satellites and their type.Satellite types are:• Circle — A circle identifies a satellite from theGPS constellation.• * Diamond — A diamond identifies a satellite fromthe GLONASS constellation.• Square — A square identifies an (SBAS)differential satellite.Note: * GLONASS satellites are only availablewhen connected to a compatible GNSS receiver.Refer to the Technical specification for yourproduct to identify your receiver type.Satellite status areaThe Satellite status area displays the followinginformation about each satellite:• Type — Identifies which constellation the satellitebelongs to.• ID — Displays the satellites identification number.• CNO (Carrier-to-noise ratio) — Displays the signalstrength 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 ofelevation and azimuth between the location of thereceiver and the satellite.Position and fix informationThe following positional and fix information isprovided:• Horizontal Dilution of Precision (HDOP)— HDOP is a measure of satellite navigationaccuracy, calculated from a number of factorsincluding satellite geometry, system errors inthe data transmission and system errors in thereceiver. A higher figure signifies a greaterpositional error. A typical receiver has an accuracyof between 5 and 15 m. As an example, assuminga receiver error of 5 m, an HDOP of 2 wouldrepresent an error of approximately 15 m. Pleaseremember that even a very low HDOP figure isNO guarantee that your receiver is providing anaccurate position. If in doubt, check the displayedvessel position in the Chart application againstyour actual proximity to a known charted object.• Estimated Horizontal Position Error (EHPE)— EHPE is a measure of the estimated error ofa position fix in the horizontal plane. The valuedisplayed indicates that your position is within acircle radius of the stated size 50% of the time.• Fix status — indicates the actual mode thereceiver is reporting:160 LightHouse MFD operation instructions
