Quark-elec NMEA Marine electronics › Forums › Marine Electronics(AIS/NMEA Multiplexer) › GPS Jitter (A026)

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  • 02/01/2019 at 7:44 pm #13501
    Anonymous

      Hi, I am seeing quite a bit of jitter in the GPS feed from a A0206 compared to a star-iv GPS puck. It is really noticeable when the device first starts up but settles down after a few mins. Even after 10mins the jitter is leading to a sog that jumps from nearly zero to 0.3 nm. It there anyway to tune this out of the system?

      Thanks in advance

      04/01/2019 at 10:49 am #14247
      Quark Elec

        Hello

        This is very odd and I haven’t come across this before. We feel there could be a few reasons for this issue with your GPS. Could you please help us to understand the scenario by answering a few of these questions?

      • which GPS antenna are you using that is causing the issues?


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      • do you have other GPS devices like IPad and mobile phones using GPS?


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      • do you have GPS from another equipment attached to your NMEA/CAN system on your boat? for example chart plotter with built in GPS.


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      • have you checked the location of the antenna to make sure it is free from general and water damage?


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      • what kind of materials is the antenna attached to and what location is the GPS antenna located?


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        please answer these questions to help us understand. we feel that the antenna is either not receiving a good enough signal due to satellite coverage (this could be down to general location of boat or the location of the antenna). or there is interference from other sources like another GPS signal nearby or other equipment causing issues.

        please let us know this information and we can go from there.

        Best regards

        Joshua

      04/01/2019 at 5:34 pm #14246
      Anonymous

        Hi, with respect to your questions

        The GPS antenna I am using one of your AS04 to evaluate the kit

        I am only using the nmea feed for now and feeding it to Expedition – see http://www.expeditionmarine.com/index.html

        There are no other feeds being used

        I am evaluating the kit at home, so water not an issue

        I have placed the antenna inside the back window so it has a clear south facing view of the sky and GpsNum is typically 7 or better

        Here’s an extract from the log file that shows the deduced SOG based on the changes in lat/lon (sorry the alignment not better)

        GpQual PDOP GpsNum GpsAge Altitude GeoSep GpsMode Lat Lon COG SOG

        1 2.4 10 13.1 45.7 2 51.4645947 -0.2279232 178 0.745

        1 2.41 7 10 45.7 2 51.464624 -0.2278743 0.582

        1 2.41 7 11.9 45.7 2 51.4646515 -0.2278438 0.502

        1 2.41 7 13.4 45.7 2 51.4646633 -0.2278328 0.422

        1 2.4 7 11.8 45.7 2 51.4646492 -0.227846 0.526

        1 2.4 7 14.2 45.7 2 51.4646615 -0.2278337 0.745

        1 2.41 7 14.9 45.7 2 51.4646615 -0.2278337 0.419

        1 2.4 7 10.4 45.7 2 51.4646515 -0.2278438 0.1

        1 2.4 7 14.3 45.7 2 51.4646763 -0.2278185 0.422

        1 2.4 7 10 45.7 2 51.4646258 -0.2278717 0.519

        1 2.4 7 15.7 45.7 2 51.4646615 -0.2278337 0.745

        10/01/2019 at 3:02 am #14248
        Anonymous

          I saw this when inadvertently feeding TWO GPS signals into an iPad app. Had to turn off the iPad GPS and the jiggle disappeared.

          HTH.

          Bill

          11/01/2019 at 10:33 am #14249
          Quark Elec

            Hello

            Yes we recommend only using one GPS source for your NMEA data. If you are using two then they will conflict due to the different positions of the GPS antennas.

            Best regards

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