GPS Satellite 'Fix' problems
  • I have just returned from 2 months touring Western USA using Navigator Free on an Archos 80 tablet running Android 4.0.4.

    I have been most impressed and think the interface far superior to the PC version.

    I did experience a few ‘glitches’ with routing but these were almost certainly due to errors and omissions in Open Street Maps.

    The TomTom (TeleAtlas) maps seem good value and I will down-load these before my next trip.

    One problem I did experience on about four occasions was an inability to get a GPS fix.

    I realise that signals can be shielded by vehicle body work but even when I took the unit outside where there was an uninterrupted view of the sky it was often many hours (often overnight) before I could get a fix. I tried closing and restarting both the tablet and then just Navigator, but without success.

    The GPS info screen would display a number of satellites (maybe up to 5 or 6) but these refused to ‘lock’and the number of satellites listed below remained zero. What do the colours (orange/yellow/green) on the bars signify? I realise that there is a minimum number of satellites requires for accurate navigation, but how many is this?

    As I write this (in UK) I can now see only 2 satellites bars: number 4 which alternates between yellow and green and 31 which is slightly higher (stronger signal?) and remains solid green. It has been like this for 15 minutes.

    I wondered whether there might be a problem with my hardware so installed a separate GPS tester. This immediately displayed 10 satellites and was ‘using’8 of them. I closed this down and checked Navigator again and now have 7 satellites! This could of course just be a coincidence.

    I would be interested to hear if anyone else has experienced the same phenomenon.

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  • I have also seen the problem whereby it is not possible to lock to the GPS even though the satellites are displayed and a lock is indicated.  I have used the following reasonably successfully:-

    https://play.google.com/store/apps/details?id=com.eclipsim.gpsstatus2&hl=en

    It is often necessary to download/reset the A-GPS data to promote a fast lock and this tools seems to accomplish this.

    To answer your question, " I realise that there is a minimum number of satellites requires for accurate navigation, but how many is this?"  try reading this link:-

    http://www.gpsinformation.net/main/gpslock.htm

    I have no idea if the info is correct but I hope this gives you a feel to the complexities of the GPS system.

    Thomas, I am also interested in the meaning of the colours, you asked, "What do the colours (orange/yellow/green) on the bars signify?" so Thomas, is there any chance of an answer to this question?

     

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