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GPS intenal antenna - can(39)t find/hold satellite signal-gctid388360

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    GPS intenal antenna - can(39)t find/hold satellite signal-gctid388360

    I've recently installed a Raymarine A57D chart plotter/fishfinder on my little fishing boat.It takes a long time for the GPS to acquire satellites and get a fix. And it often drops them, losing the fix. If I'm headed north, I get much better reception. But if I'm headed south, and the windshield occludes the southern sky, I get 4 birds, maybe 5 at best, and I lose my fix.The unit sits on the dash, in behind a glass windshield (Taylormade windshield). The boat has no hardtop or canvas. Except for the windshield, the unit should be able to see the full sky all the time.I've talked to Raymarine and the retailer (local guy who I know well). They both say this antenna has a good track record; no record of complaints.Raymarine gave me a compact flash card with the latest software to install. I was hopeful that would help, but found that my unit already had the latest version/build. Argh!Raymarine tech support suggested I set my SOG/COG filter to high, but I know this won't help me hold a satellite signal.I'm facing 2 options;1. Take the unit off and ship it to Raymarine, which means I'll lose it for weeks and weeks, or2. Buy the external antenna (>$300). The whole unit was

    #2
    Can you move the unit temporarily so that the windshield can be completely eliminated from being a possible source of interference?

    Comment


      #3
      I have a Lowrance and installed the external antenna on the advice of my local marina. It has worked faultlessly for 6 years now. Recently, I spoke with Lowrance at a boat show and they told me that the internal antennas work very well unless placed below a metal hardtop, so that if I were to replace my unit (with a larger screen model) I needn't worry about the antenna.

      Having said all of this, you may just have a bum unit from how you've described your installation.
      2007 Discovery 246
      300mpi BIII
      Welcome island Lake Superior

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        #4
        Mike,

        Can you reload the firmware? Even if its the current version, I would try to reload again anyway. Maybe a factory reset?

        I have had a lowrance fry the "puck" external antenna before, had to replace it. It was a 24v power surge over my 12v lines, gg repair shop cant hook up batteries right.

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          #5
          I have the identical unit installed in the dash under a hardtop with no external antenna . it works great. is there possibly some thing interfering with it under the dash ?

          Comment


            #6
            Take it out of the boat and power it with a battery. See if the unit itself with no other interference shows high satellite signal levels or not. You can get interference not just from obstructions, but also electrical noise and other electrical issues.

            Obstructions with GPS can seem really minor and cause a problem. I had a unit mounted into the dash of my 2455 so the only obstruction was fiberglass, and that caused it to lose position all the time. Had to add an external receiver.

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              #7
              I like to test boat electronics at home before I use them on the boat. I use a cheap Radio Shack AC/DC converter, wire up the unit and mess around with it until I'm comfortable that it works and that I know how to use it.

              I've never had a problem with an internal antenna GPS unit not getting or holding signal. I have two chartplotters on my boat and both have internal antennas.

              I suspect you have a bad unit. How about other boats in your location? Do they get good signal with internal ants?

              Comment


                #8
                Mike when I have my boat hauled to Midland I have to go into my setup on the GPS and tell it I am now in a different area. If I travel the Severn through the locks it makes the switch to Georgian Bay from Lake Ontario area no problem. The first time it did it, it was having trouble locating the sat, for close to 5 min. Once I change the area it is less than a second.

                I think your external antenna is fried, the summer you came north to Little Current, Steve fried both external antennas on his 2955, it was caused by a radar unit. It was doing the same as yours we used my ext ant on his boat and his units worked fine, it was an expensive replace for him.

                Ken
                300SD all options sold.

                Comment


                  #9
                  When I mounted my Lorance there was a note about not being to close to an electrical device. Recheck your instalation manual for something like this note. You probably already did this. Gary
                  GARCHAR
                  1988 2655
                  2009 Volvo Penta 5.7 300 hp DP F3s
                  Twice Past Commodore
                  Northwest Outboard Trailer Sailors, Eugene,OR

                  Comment


                    #10
                    If the unit can't pick up and lock on the sats in an open boat it's defective.

                    I have a Lowrance on my F/B with internal antenna, no problems.

                    I used a hand held GPS when I travel for street maps all over the world (just got back from England) and it sometimes picks up sats inside the steel cruise ship. It has no trouble getting a fix in my town house, first floor and I have never had an issue when it was in the open.

                    When I worked for the Ministry I tested several brands of GPS with internal antennas and the only time I had issues was inside metal enclosures. As long as it's shooting through F/G or canvas their should be no issue.

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                      #11
                      Thanks for the help everybody. It looks like I need an external antenna. My problem is the Taylormade windshield; it must have some unique coating in the safety glass lamination.

                      I removed the GPS unit from the boat, and made up a jumper so I could power it up remotely using a 12VDC jump box. Standing on my dock, holding the GPS unit in my hand, the nearest building is about 200' away and I picked up 10 or more satellites (on average).

                      Then, still using the jump box power supply I returned the plotter to the boat (on the trailer in the barn) but not under the shadow of the windshield. Still had 6 satellites or more, while in the barn. Moving it under the windshield near its mount dropped me to 4-6 satellites, and all weak signals. And the unit couldn't find those satellites again if I restarted the GPS.

                      I then returned the plotter to its proper dash mount and reconnected it to the boat's power supply and pulled the boat around with the tractor. As long as the windshield wasn't between the unit and the southern sky, I was OK.

                      So, it's that damn Taylormade windshield. Who's got a new Raystar 130 for sale, cheap?

                      Comment


                        #12
                        Interesting. Is the windshield tinted? A lot of tint contains metal.

                        Comment


                          #13
                          SwampNut wrote:
                          Interesting. Is the windshield tinted? A lot of tint contains metal.
                          Yes, but not a deep tint. It has a very solid feel to it; heavier frame than most windshields on runabouts. I have no idea what they put into the safety glass laminations on this one but it sure does attenuate satellite signal.

                          I often remind my kids that serious problems are those you can't fix with money. This is not a serious problem.

                          Comment


                            #14
                            Yeah, metallic tint then I'm sure. Good to know next time someone asks.

                            Comment


                              #15
                              whiskywizard wrote:
                              Yes, but not a deep tint. It has a very solid feel to it; heavier frame than most windshields on runabouts. I have no idea what they put into the safety glass laminations on this one but it sure does attenuate satellite signal.

                              I often remind my kids that serious problems are those you can't fix with money. This is not a serious problem.
                              The safety glass has a plastic lamination.......the tint is usually plastic as well...sounds like you got lucky with some sort of metal. Never heard of that before!

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