Carlson Brx7

If cost is not an option, you really want a Trimble R12.
They are just simply streets ahead of anything that came before - especially under canopy

I've heard good things here about the Carlson under canopy. I guess that the thing to do is to a demo with all the models you may be considering.

Even if cost is not an issue, interoperability with your chosen data collectors is a major convenience and a worthy consideration.

For the record, I'm pretty happy with my pair of Leica GS18's.

I’ve heard the Carlson Brx7’s are outstanding. Curious though, I am running GeoMax Zenith 35 Pro’s as well right now and they work incredible under canopy. I’m also using a Satel 35W external radio which may have something to do with it.

I use a 35w radio sometimes as well. My issue is under conifers where, sometimes, it takes a long time to get a fix. Possibly a radio issue, I had never thought to consistently use the 35w radio. The only applications I use it now are when I can't find a base location that is suitable in the nearby area.

@caleb

Have you checked with dealer if you have latest firmware on both receivers and are you using all constellations?

I know I'm using all constellations, but firmware hasn't been checked for awhile. Good point I will check into it, thank you!

I run Zenith40's personally and find they are just as precise as the Lecia GS18's I use for a firm I contract to. Obviously no tilt but I turn that off for the boundary work I do anyway as I want <10mm 2d positions. I find GNSS passible under light canopy for topo but for accurate control I like to be two tree lengths from nearest tree for GNSS.

Think the Zenith35 Pro has same 555 channel chip as Zenith40 but different firmware, no extra safe option for the Zenith40 (not that I can tell if extrasafe makes much difference).

For radio range what makes a bigger difference than a higher powered radio is getting a 1m whip aerial, long cable and getting it up on a 5m topo pole, I've found. Also putting your base on the highest point around helps.

I favor the Trimble R12i honestly but I have been head to head with Carlson BRX7 in canopy.

There is nothing wrong at all with the BRX7. If you wanted to compare the BRX7 to R12I. They are not far from each other in all honesty. The price difference is favorable for the Carlson for sure. Now the reason I like Trimble is not just the GNSS reciever but the total solution from Trimble Access in the field and the office of Trimble Business center.

If you don’t get caught up into the sales pitches of take a 5 second shot or 30 second shot and follow good field procedures and multiple observations at a gap in time between those preferably 4 hours but 2 to 3 hours at minimum you can get some good results when in canopy you might have to make a 3rd or 4th observation and at minimum I use a 180 epochs for control and any property corners. I do not like to Topo in canopy unless I have a lot of relief and when I have had to I always set up random points that are flush with the ground to come back and perform spot checks as I have seen some bad results at times. The Carlson BRX7 performance was great no doubt. Are results were minimal differences side by side in almost every observation. However there were some that differed outside the error of comfort at times. It amazed the guy that was running it as he was a one shot and done person and said he never knew if the data collector said it was good then it must be. By doing multiple observations as we ran the circuit he saw why I did the procedure I did.

We were seeing who could initialize faster the end precision values how close our results were to each other and the known.

Trimble was a bit faster most of the time resolving but in the cases where it did not beat the Carlson also proved that those were the same points when we returned where The Trimble position was closer to the truth than the Carlson. Setting side beside the Trimble would come in and out of a good solution more than the Carlson as when the Carlson was resolved it seemed it stayed resolved but I believe this is because Trimble was doing more checks more often but I have no facts of this. But when Trimble fixed and leveled out for the full 180 epochs it was good . The Carlson did not prove to do this as often. But if I were a solo small shop it would take a lot to not buy the Carlson on the price point alone. Now I have very little experience with carlsons data collection software and I am sure I could figure it out. If I was thrown into a situation today I would go Trimble just a lot of that is I know it and understand it and the learning curve would be minimal. The other is the longevity and support I would be paying for. Yes maintenance agreements are a cost and high for Trimble but I would still eat that to a certain extent for the benefit of saving so much time in being able to work and manage data from field to office and back in a very good workflow and the ease of performing qa/qc on that side.

".....the reason I like Trimble is not just the GNSS reciever but the
total solution from Trimble Access in the field and the office of
Trimble Business center....."

Bingo!! This is ever so much important. There really isn't much - if anything at all - between one modern receiver and another. It is all about how the system fits into your particular workflow.

So true. I am sure they will comeback history always seems to repeat itself in some form or another. But for now the days of mismatch of equipment and software are not as proficient in my personal opinion than to choose a SYSTEM and role with it completely. I look more at Trimble as a complete system than others although the gap is closing for sure and fact

Carlson cad the field collector and them now OEM hardware is not a bad system at all.

If Trimble is lacking in anything it’s the final drafting cad side but even that is not bad on TBC it just different and is completely achievable while from a cad only standpoint Carlson has it beat in many aspects of being able to run it on top of a autodesk platform I think if Trimble would have implemented more of the draft side from Terramodel which is where I had mor drafting time in it would have been so many miles ahead of everybody from a total system approach

Carlson BRx7 is superb under canopy.