GPS App Questions

Discussion in 'GPS Software' started by Cedric, Jan 2, 2023.

  1. Cedric

    Cedric

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    I use GPS measurement to record Family History related locations. I want to pass onto succeeding generations, item locations that may be lost sometime in the future. Hence GPS seems to be more time proof than an address (street names might change over time, road location might change, cemeteries might be redeveloped thereby negating current row and grave numbers, etc). It seems to me that 3 metre accuracy is adequate to locate a building, but to locate a grave I need 1 m. GPS Status often reports 3 m accuracy, but I need improved methods and/or hardware to get 1m accuracy.

    Over the last 10-years I have used several devices, 1st a Garmin nuvi 500 (it didn't seem to give good results), later several phones. I currently use a Samsung S20 FE 5G, on the Telstra network which is claimed to have the best network coverage of any network in Australia. A lot of my measurements are made in country areas.

    I realise the Australian tectonic plate is one of the fastest moving plate on our planet ~6 cm pa (6 metres per century) (and different parts are moving in differing rates or directions). So I record date of measurement and ellipsoid, reported accuracy, in addition to Lat and Long.

    At present I have the GPS Status App installed on the phone. So 2 rather different questions:
    Q1) What GPS App gives good accuracy, and hopefully reliable error estimates?
    Q2) Am I correct the GPS Status App uses the WGS84 ellipsoid?
     
    Cedric, Jan 2, 2023
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  2. Cedric

    Nuvi-Nebie Moderator

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    The GPS receiver in your cell phone is not dependant on cell phone network coverage at all, the GPS will work when you have zero network signal, all it needs to 'see' are satellites, also the GPS receiver is not dependant on any App. running on your cell phone, the satellite signals are received by a GPS antenna inside the cell phone and are then passed to a GPS receiver 'chip', the output of the chip are NMEA sentences like this :-

    Apps can use these sentences from the receiver but can't change the accuracy of the Latitude / Longitude that they contain

    You can get better accuracy with a dedicated GPS or cell phone by performing GPS averaging, where the receiver is kept stationary while a number of Lat. / Long. measurements are taken and then averaged out to get a better 'guess' at the location, or by using a GPS unit that uses a dual frequently receiver (See HERE), such as the GARMIN GPSMAP 65 / 66
     
    Nuvi-Nebie, Jan 2, 2023
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  3. Cedric

    Cedric

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    Nuvi-Nebie,
    Thanks for your info, I am trying to understand how I improve my measurement accuracy, within a limited budget.
    My practice is to start an observation by checking co-ordinates shown for a known survey mark with that mark's published co-ordinates, then take several observations of the item I am interested in, then observe the survey mark again.
    I may not need Internet for my phone to observe co-ordinates, but I need Internet to find nearby survey marks, and details of them - eg as shown in the NSW SCIMS database of survey marks. So it pays to download info from SCIMS prior to traveling to the point of interest - and as survey points are regularly destroyed by construction works and other causes, it pays to download several nearby points.

    Turning to the list of dual-band items, it shows One Plus use the Snapdragon 865. The gsmarena website shows my phone (Samsung Galaxy S20 FE 5G) has Qualcomm SM8250 Snapdragon 865 5G (7 nm+) chipset. I also have a Nokia 6.1, which gsmarena shows has a Qualcomm SDM630 Snapdragon 630 (14 nm) Chipset.
    Am I correct in understanding the Samsung can receive dual frequencies? If so, I guess I have to find an App to do that.
     
    Cedric, Jan 3, 2023
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  4. Cedric

    Nuvi-Nebie Moderator

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    Another way of getting a better satellite 'fix' is to approach the marker from 3 different directions, obviously each time you arrive at the marker you should get the same Lat. / Long. readings but due to errors it is likey you will get 3 different locations in a triangle with the true location somewhere inside it

    The App. 'GPS Test' by Barbeaudev shown in the link above will show if you are getting dual band information, look in the CF column for '5' entries

    GPSTest.jpg

    2023-01-03_11.14.56.jpg
     
    Nuvi-Nebie, Jan 3, 2023
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