[CA] [CA11] Internal GPS Behavior - Axiom 9 - Should I consider an External GPS antenna?

[ventus]

I have noticed over this past season my Axiom 9 sometimes takes a while to gather satellites and get a fix on position. Sometimes I even have to restart the internal GPS. I have also noticed that the SOG will jump around sometimes (ex...6.5 to 13, then come back down to 6.5 if I am going 6.5). This behavior doesn't happen all the time but does happen often. I have the Axiom 9 as the GPS master and it is located in my sailboats cockpit under a sunbrella Bimini and inside a NavPod. Should I consider an auxiliary GPS antenna? If so, which is best for my network? I would need to rail mount it. I have a GPS antenna on the rail currently for the AIS700, could I mount this one next to that without creating any interference issues?

I have attached my system diagram for reference.

[Chuck - Raymarine - Moderator]

Welcome back to the Raymarine Forum Ventus,

Chartplotting / MFD products featuring internal GPS receivers differ in their sensitivity, not only due to the quality of the GPS receiver/antenna assemblies used, but also in the RF interference effects of additional circuity (ex. fishfinder, video processing, etc.) housed within the the product. Accordingly, satisfactory GPS reception of a prior Chartplotter / MFD in an installation location is no guarantee of another Chartplotting / MFD design in that same location. While a hard top would qualify as an obstruction to GPS signal, a fabric bimini would not typically be considered an obstruction which should offer significant GPS signal reduction. That said, should the chartplotting product / MFD be the system's GPS data source and be installed in a location affording it an unobstructed view of the skies overhead and be unable to acquire a GPS position FIX, intermittently lose GPS FIX, be slow to acquire GPS position FIX (should take less than 3 minutes), or produce an inaccurate GPS position FIX (typically accompanied by high HDOP ... which is normally 1.0 or less, then it would be recommended that the chartplotting product / MFD be sent to Raymarine’s Product Repair Center to be bench checked / serviced. Alternatively, an external GPS sensor (ex. Raystar 150, Raystar 130, etc.) may be interfaced to the system to function as the system's GPS data source. Please click here to view a FAQ addressing NMEA's recommendations regarding minimum antenna spacing distances, where it recommends a minimum of 1/2' spacing of GPS antennas & GPS sensors.