Carlson BRx7
Well, I am happy to say that Carlson BRx7 sent me a nice little email today, with pics of their gear being used in challenging places.
I have a few questions, from the USERS and MAKERS of these kind of Pics.
What method is used to determine accuracy? How do you analyze and extract the good data, from the bad? Working in deep woods, introduces curved lines from the Satellite, to the GPS. These "Curved" lines are bouncing around all over. My experience with this kind of equation is that you can spend more time, and take more and more shots, until you start believing some of the shots. This process is automated by Javad, and that's quite satisfying.
Can anybody articulate the quality of data in the deep dark woods, and how to determine what is good and what is bad?
I have used the old Legacy E from Topcon.
I have used Javad, and consider them to be one of the pioneers in data analysis, in bad places.
So, can I get feedback?
I know Trimble has been working on this, and so have others.
It is our job to try to keep current with our gear.
Thanks
Nate
Every RTK unit I've ever used, and I've used multiple examples of each of the big 3, yields a coordinate quality estimate. These are aspirational. A redundant measurement, preferably from an alternate base, is the thing to have.
"These are aspirational."
That sums it up nicely.
And, BTW, your idea of different solutions with the same results is essentially what JAVAD claimed with their approach.
Which leads to a kind of unrelated observation:
Unfortunately, the entire precision location through GNSS industry is predicated on exaggeration and secrecy and an intense desire to "black-box" and claim that their approach is best, but offer zero independent analysis that would prove this. Every test and lab analysis is cloaked with NDA's and vague assertions.
<div>“These are aspirational.”
</div><div>
I have been trying to break my javad for years.
It's pretty good. Not broken yet.
Nate
</div>
I went out this afternoon with a solo guy to stake some property lines and another job for site plan. Anyway we he had the BRx6+. It was not a bad set up. It does seem clunky on all the steps to get connected to start the base and rover Bluetooth connection etc. I guess Trimble spoiled me in all that as it’s pretty seemless if you have the survey style or styles set up and ready. First time me running a Carlson surveyor 2. But me and the LS had a nice wet day and got what needed to be done done. He does want to test it in canopy soon so that will have to be another weekend for me to figure out its breaking points and how to best approach that. Redundancy is usually king when pushing any of them hard for sure.
Nate, I am a former Trimble guy who converted to Carlson. I considered Javad, but, at the time, I want an integrated GPS-total station-data collector work flow. When I made my switch, I felt most confident with Carlson. This is just me.
My focus was on the BRx7 GPS base/rover setup. I wanted to use it as much as possible. So, I was determined to use it in challenging situations. It hasn't disappointed.
To answer your question, Carlson uses a method it calls "SureFix". The Hemisphere S631 and Stonex S900 also use this method as they are essentially rebranded BRx7's.
SureFix basically uses all satellites available and calculates fixes with two different methods (algorithms). It then compares the two different solutions and uses statistical analysis to limit accepted solutions that maintain a precision specified in Carlson SurPC's survey style.You can also setup styles to include multiple sub-observations within an overall observation and an antenna dump at each sub-observation. You can set up custom styles with different precisions/techiniques/observation durations.
To sum up my experience, I would state the following. When I have checked my BRx7 GPS solutions with a gun, if SureFix says it's good, then horizontally it's good (within required survey tolerances). For vertical, I would say it's good 95% of the time. The other 5% I have found vertical error up to 0.15' in challenging situations. You just can't replace your brain with fancy equipment and software - we have to use our equipment responsibly.
Can you explain how Javad approaches its solutions and QA/QC methods?
Carlson's BRx7's and SurvPC use a method they call SureFix.
Surefix uses all available satellites and computes 2 different solutions from 2 different fixes. The two different fixes use different methods/algorithms.
Through the use of a setup survey style, observations can be of varying durations, have re-fixes at specified intervals, and require a certain precision in the two different fixes. This is all customizable.
When I first started using this setup, I ran several independent checks with a gun. In my experience, if it says SureFixed, horizontal is good. In a very few occasions, I had some vertical error up to 0.15'. So, be careful with the vertical in tough conditions.
Javad has been dividing signals, and developing fixes from differing points of view, for a long time. They finally came up with the idea that anything within 0.20' is a "Good Fix". I am not sure about vertical error allowance. The idea is that is the STARTING place. IF you are getting a shot on a power pole, or an old fence corner, usually 0.2' is good enough. Then, if you NEED more accuracy, leave it to cook longer. And, it can cook out most stuff. My usual goal for boundary work is 0.05'. But, it is a developing technology.
Nate
If a Leica, Trimble, or even a Topcon receiver is telling you that it is fixed you can rely on ±0.2' results. The questionable part is when they are telling you that the coordinate quality is 0.02', you may be actually getting anywhere between perfect and ±0.04', more or less. But a "fix" meaning better than ±0.2' is not unique to Javad.
Are you saying that coordinate quality is the RMS HZ and VT the precisions . I never heard that term used that way. Yeah when I am teaching guys in the field. I will often let them see it get down to the .02’ at DRMS then switch it to 95% confidence so they have and understanding visually that is not the accuracy. It’s an estimate at whatever sigma. They have set.
