Carlson BRx6+

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Just got the BRx6+, so I'm not entirely sure yet.?ÿ But I can say that the BRx5 was damn good in the canopy. This past summer I was staking out to a couple corners in the back of 5 acre parcel, just to find them.?ÿ They came in under a tenth to record position. So with the additional constellations it reads over the BRx5, I would hope it's even better than the previous version.?ÿ?ÿ

I've discovered similar things. What amazes me is the ability to get these amazingly tight floats, RMS figures almost identical to 'fix' figures.

What concerns me though is the system's ability to just give bad location data. I just had to have the crew reshoot a drainage channel that the elevations were bad by almost 15 feet (i.e. top elevations were about 5 feet below the toe elevations). There doesn't seem to be any reason for the bad coordinates other than the GPS (or perhaps the Carlson DC) just wanted to give/record bad results. Got to keep a sharp eye on the results for sure.

@andrew-clark

That sounds like the DC parameters where changed to accept a float solution for those points.

I did that once, when I was trying to just get a rough location on a trail.  Walked the whole thing accepting float solutions that would be close enough to plot, then went back to boundary work and forgot to change the DC to 'accept fixed only'  Had to redo a couple of boundary monuments after that.

@toivo1037

I wish it were that simple. My DC is set to only accept a fix solution. Usually the elevation bust or horizontal bust is so bad it stands out. It also helps to live in a generally flat area, so a sudden elevation change tends to stand out.

@ken I agree with the BRX5 as far as horizontal positioning under umbrage.?ÿ the verticals haven't been that bad either. plus minus a tenth or so.?ÿ I assume the BRX6 is much lighter ??ÿ ?ÿ

Have a good one !?ÿ

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@andrew-clark

Andrew,

Did you have your Carlson DC to accept only verified fixes or just regular fixes?

@frank-willis Where do you set that at? We try to do a 3 epoch average on our topo shots, but it doesn't seem to catch the problem.

@andrew-clark

Andrew, I don't have Carlson GNSS software here because I am using Trimble GPS, but I have spoken with others using it, and they say there is a setting for that.?ÿ I know that Carlson checks the heck out of manufactured devices before they put their name on it, and in fact communicated with Bruce Carlson yesterday who clearly explained to me the absolutely extreme, rigorous testing they do before adopting anything and releasing for surveyor use.?ÿ I know they are good, but I had no idea that they go to that extreme.?ÿ I've never had a single?ÿ non-resolvable problem with anything Carlson has ever sold me over 25 years, and there is no better tech support than theirs.

So I recommend you check with support and get the setting for point verification.?ÿ Three epochs is not enough to check a point that might have had minimal statistical checking prior to display.?ÿ RMS means nothing other than it compares the data collected during that particular observation.?ÿ A lot more goes into it with Carlson's software, including what is involved in the point verification setting to protect against bad fixes.

I hope that setting fixes it.?ÿ

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@andrew-clark The setting for where to "Store Fixed Only (GPS)" is found under the Equip tab -- Configure:

For GNSS receivers that support the "SureFix" configuration, there will also be an additional toggle that will only permit the storage of measurements that achieve that quality indicator of the receiver. Bear in mind that in challenging environments (e.g. high multi-path and canopy), the enabling of a SureFixed solution may take longer-than-desired to achieve. In these situations, reverting to "Store Fixed Only (GPS)" may be the preferred solution.

Additional quality checks can be established under Equip -- Tolerances to help prevent (or allow) measurements based on user- and job-constraints.

I hope this information helps.

@ladd-nelson I didn't have that option in the configure screen. It was found under the GPS Rover Settings, Advanced tab. Support was quite helpful.