Accurate GPS

Discussion in 'GPS Technical Discussion' started by Name Redacted, Jun 15, 2021.

  1. Name Redacted

    Name Redacted

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    I am looking for a GPS that can be used to locate existing property corners in heavy brush. My older Garmin 60cx is not very accurate (30-50ft radius by my estimate). I have spent a lot of time cutting brush and scratching in the dirt. Is there a better unit that will get me closer? Hopefully within ten feet. I am looking at a Garmin 66sr but it is not clear how much better it will be. Garmin says it has the best accuracy of any handheld they offer but don't give specifics. I can't spend the money on a survey quality unit. Is the 66sr even using the L5 enhancement?

    Any thoughts on the accuracy of the 66sr or are there better alternatives? Preferably something cheaper than the 66sr.

    John
     
    Name Redacted, Jun 15, 2021
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  2. Name Redacted

    Nuvi-Nebie Moderator

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    The Gpsmap 66sr does use 'dual frequency' GNSS (L1 + L5) and is undoubtedly more accurate than a 60cx, the Gpsmap 65/65s uses the same 'dual frequency' technology and is considerably cheaper, the question is will either of these units do what you want, I would say under a clear sky - yes, under heavy brush, it's hard to say, this is why Garmin are vague about accuracy, there are other steps that can help, most Garmin hand helds can perform waypoint averaging where a stationary unit takes multiple location measurements and then averages thrn into a single more accure location

    Take a look at the 'dual frequency' info here :-
    https://www.gps-forums.com/threads/what-is-dual-band-gnss.46938/

    I have a tablet with 'dual frequency' and I would expect either of the above Garmin unit to be at least as accurate as this :-
    2021-06-15_23.37.27.jpg
     
    Nuvi-Nebie, Jun 15, 2021
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  3. Name Redacted

    Name Redacted

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    Great response. The brush is only a couple of feet high and the trees are kind of sparse in the area so I generally have a clear sky view. I have another question. How do I tell which units are dual frequency? I will be in the market for a replacement tablet and/or smart phone in the near future. It might be smart to roll the money I was planning to spent on a hand held into a upgraded tablet or smartphone if it is just as accurate as the 65/65s/66sr. I could not find the dual frequency GPS in the tech specifications of any of the tablets or smart phones that I am interested in. Do you know of a list handheld/tablets/smartphones with dual frequency units?
     
    Name Redacted, Jun 16, 2021
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  4. Name Redacted

    Name Redacted

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    After doing about 3 searches the following list was found. The list is based on crowdsourced tests using GPSTest android app. The interesting thing is some tests showed Dual Frequency is "supported" and "not supported" on seemingly identical units in different tests. I guess that happens with crowdsourcing a test. It is usually consistent and still useful.
    Code:
    https://docs.google.com/spreadsheets/d/1jXtRCoEnnFNWj6_oFlVWflsf-b0jkfZpyhN-BXsv7uo/edit#gid=0
    
    You can actually download the excel spreadsheet and sort on it.
     
    Name Redacted, Jun 16, 2021
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  5. Name Redacted

    Nuvi-Nebie Moderator

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    As I said in the What is Dual Band page it is not easy to determin which Android / dedicated devices are currently working in dual frequency because you need a 'dual band chip' to be fitted BUT you also need the correct level of operating system and dual band software running on the device, I have found on my Samsung Tab A7 (2020) that even with all this in place that the unit doesn't always seem to use the second frequency for some reason
     
    Nuvi-Nebie, Jun 16, 2021
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