That test doesn't tell you anything more than the consistency of the instrument in that location. Being able to prove work by independent means is the only real check (I don't mean on every shot just a number of times to prove the concept)
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Do you ever verify these points using a total station from control out in the open where GNSS is unaffected? We did with the Javad LS base rover (GPS/GLO only) pair and the boss and I were disappointed with the results, certainty didn't match up with the videos we had seen online. GNSS fixes would agree but not with total station positions. Worked like any other GNSS in the open though.
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The auditing government surveyor here tells a story about one job where there were three original monuments placed on a straight line on a street, 1&3 in the open and 2 had a tree nearby. The surveyor did the job with GNSS and said monument 2 by the tree was offline now. Shortly after the auditing?ÿ surveyor sets up his GNSS and gets the same result, he then sets up his total station and lo and behold the three marks are actually still on line. He said this is common where people use the GNSS to save time but is the wrong tool for the job (urban monuments here are set to 0.01-0.02m typically).
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Hence my reluctance to believe GNSS results in challenging conditions that aren't regularly verified by independent means.
You can get more shots faster with a nail in the field, a robot, here is the typical tradeoff.
It takes 5 or 10 or 15 minutes per point, (some of these are multiple shots) and you have typicly 0.05' of error.
?ÿThis is a normal picture.
Nate
15 minutes per observation???ÿ Is that how long it takes for you to get a fix or are you choosing to observe for that long??ÿ?ÿ
If you are doing RTK, there's no reason (if your receiver is modern - aka 4 constellation) to observe RTK for long than when the predicted precision values stop decreasing.?ÿ So it could be as short at 15 seconds.?ÿ With RTK, all you are doing is observing where you are (delta X,Y,Z) relative to your base receiver.?ÿ It's like a total station side shot recording those same delta values.
Well worth a watch to temper your IMU expectations. Great for topo/setout, not for bounday/control (unless just rough boundary staking)
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Disagree. A coworker (We use Trimble R12i) set a property pin being only able to push the bottom of a fence out at the time using RTK and tilted rod, and wasn't able to get over the fence. The next time he was by there, the owner was there and could get in the fence. He checked the pin that he set, using a plumb pole this time. Pin checked within 0.03' of stakeout coordinates.?ÿ In the hills and with trees around.
And I had a pipe that was at the edge of a big tree, which was growing above the pipe. No way to get a plumb rod over it. If located by a total station, would have to set a point, setup over it, and maybe even locate the pipe reflectorlessly to not hack some of the tree off (never want to upset property owners or to bicker who owns the tree or if it's in the road r/w or not.?ÿ I observed the pipe 3 times with a titled rod, resetting satellite tracking after each one.?ÿ Oh and the tree was on the south side of the pipe.?ÿ I'll have observed that pipe within 0.03' if doing it with a total station, and saved 45 minutes too.
I agree REPEATABILITY does not equate to accuracy.... So, do your test like this:
Set 5 nails down in the gnarly hole between some trees.
Set 2 nails out in wide open use one for backsite, occupying the other with total station. Take doubled angle shots on the 5 nails. Now gps on them. With a javad.
Do this all day long. The scatter of epochs, and shape of the scatter will generate a single coord, with an estimated accuracy, that is reasonable.
Wonder if our tree cover is different to yours and affects signal differently? Could never work out why our pair of LS's never seemed to match up with what we saw on Javad forums.
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Our pine forests are GNSS no go (also radiata pine eats rtk signal, lucky if you get 500m when on a farm it's more like 5km) and the native bush not much better.
Yep can always have some great results that beat the product spec but the spec sheets state (Leica/Trimble at least) that the IMU adds additional uncertainty to the standard rtk 8mm + 1ppm.?ÿ Also those values are only 68% confidence so I double them which gets closer to the 95% level.
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Once you've done it a hundred times and ninety five have the same precision I'd be impressed.
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Everyone's boundary work will have a different precision requirement so was more making the point it adds error to standard GNSS obs (Assuming your gear is correctly adjusted, not always a safe bet with some crews. If your pole bubble not checked much it may be an improvement!).
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For the record if I can afford it next time I buy I certainly want the IMU rover, obviously no point getting one at the base unless you split them as network rovers.
A javad shot is NOT the same as a shot from any other brand.
It is a large pile of sequences, and resets, that flushes out the bad data. And, with the good data, gives you a pretty good estimate of its tolerances, or hundredths of slop.
I will agree that decade old GPS equipment should be upgraded because it has made quantum leaps in that time.?ÿ New equipment will change your life.?ÿ Trimble is great stuff but spendy, Carlson makes a fine receiver that I've heard good things about.?ÿ?ÿ
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I spent a lot of time deciding which way to go and went with Javad and couldn't be happier.?ÿ I have their latest and greatest and it gets shots (good shots) in places you would never believe.?ÿ More than that, the information available on each shot allows you to instantly judge how trustworthy each shot is.?ÿ Another bonus is the compact package.?ÿ You can put the rover head on a collapsible lightweight pole and it is its own data collector so no heavy chunk on the side.?ÿ You can also get the Jtip which is a screw on metal detector on the bottom of the rod and head deep into enemy territory by yourself with less gear and weight.?ÿ I am also a solo guy and lean and mean is important.
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Not sure how fast you want to make a decision but the decision makers at Javad corporate have realized that word of mouth has been their best advertising so they have knocked off 25% for a base/rover package until the end of May (Monday) I believe which will save a purchaser over $8,000.?ÿ You can get what I think is not only the best priced but the best GPS equipment available in the world for about $25,000.?ÿ Like Nate, I am not a salesman, just a surveyor that loves his equipment.
Mine is the OLD not upgraded LS. I'm using a t2 on base. I've turned on EVERYTHING the t2 can do. (I got help from another user, who is smarter than I am, to do this) so, I'm running all the USA satellites, all GLONASS, and a portion of bideu, and a portion of Galileo.
I'm running the 2 engine firmware. It's as good as it can do. Without spending some money.?ÿ
I've ordered a new t3. It's not here yet. This will give me full 4 constellation. But, the LS will not fully process all this data, as good as the LS plus will. Robert, there is alot more going on in a javad, than probably any other gear.?ÿ
After I get both the t3, and LS upgrade, you will hear more noise out of me.
