I have learned that when it gets a shot, in the woods, it makes a PILE of dots on the screen. This pile represents a compilation of all the shots, on that point. The actual coordinate is usually inside that blob of dots on the screen. BUT it is GIVING you a "in the field" graphical representation, of that shot. So that you can quality check it. When you do a shot like the one above, in a field, the 0.032' number is the SIZE of the approximately 1" square. And all the shots are there. I did a woods shot, (not shown) that had that blob about 0.16' across. In other words, accuracy IS degraded in the woods. BUT, you can SEE it, and decide what to do with it. In other words, you can SEE what you are doing.
The above shot in the thicket, was a job for my dad. He is 88. He was trying to tell me what to do.. (fathom that!) and eventually came back to see what I was doing. His moment was when he said: "That thing tells you where to go". I had used it to get within a tenth, and dug, without a metal detector, and found an old rebar.....
There have been about 6 updates to the J-Field software, in the 6 wks or so I have owned it. The software engineers, have personally responded to my comments. And, have made changes in the software. I knew I was getting on a ride, that was going to change as I rode. And, so far, it has changed for the better. And, the company has been very responsive to any and all my ideas.
I wish I had gotten one of these 30 yrs ago! He he he
Nate
Here is the screen shot, taken at the end of 200 epochs. As you can see, it generated a horizontal box, that is 0.108 square. And, all the coords it shot were there. The vertical was worse. It was 0.213'
I had total station data already on the above point. (no vertical) The actual coord for the above shot was 0.08' away. from the green dot, (Which is what is stored in the LS) I shot this several times.
This was the worst shot. I picked the worst shot on purpose.
The better shots had a square box about 0.04' square.
The average of 4 shots on the above point, was within 0.025' of the total station shot. And, I was on this point for 8 minutes. That is a total time of 8 minutes.
What I'm saying, is that I am playing with this new equipment, and learning. And, if you want to really tie a point down well, shoot it a number of times, and take their average. We are talking near total station accuracy, if you let it cook for a bit.
I will also say that it has nearly doubled my field efficiency. Even with all the redundancy, and cooking out shots, and checking their spread. Since I am still learning, I want to kind of test things, against what I know.
BTW, the total station data, was derived from a least squares adjusted post processed network, of control, that also had alot of EXTRA time in it, so that a Static GPS point that could have been good in 1/2 hr, was typically shot for 2 hrs. and then using a leica gun to shoot monuments. So, maybe there is a hundredth or 2 there too. Most shots fit within 0.04 of the total station work.
What do I think? I like it. Does it work as good as a total station? well, yes, and no. You can take individual shots with a total station faster, into thickets. And they will be more accurate. But, it does cook out the bad inits. And does a pretty good job of cooking out a pile of shots, that are in bad environments. It took about 2 minutes total to get the above shot. It did resets, resetting the GPS engines. At the point when it stored the shot, it had 5 GPS engines fixed.
If you can take a little time, and get several shots, it will improve the specific accuracy, in the woods.
So the receiver and data collector are the same unit? Isn't that a pain when you are doing a topo and you have to reach up constantly to punch in new codes?
Allen Wrench, post: 350453, member: 6172 wrote: So the receiver and data collector are the same unit? Isn't that a pain when you are doing a topo and you have to reach up constantly to punch in new codes?
No, there's an app for that:) android or iPhone.
Allen Wrench, post: 350453, member: 6172 wrote: So the receiver and data collector are the same unit? Isn't that a pain when you are doing a topo and you have to reach up constantly to punch in new codes?
Yes, they are in the same unit which is typically operated at head height so you don't really need to "reach up". I find this makes it a more ergonomic design to operate and input data as it doesn't require the user to hunch over to operate and input data. I know in the past, I have found using a traditional data collector will cause my neck to become sore after a long day of stakeout work, this is not the case with the LS.
You can use the capability to have a shot triggered by simply putting the pole on the point to me measured. No button push required.
Very little button pushing is required. If you are doing cross section topo, just let Auto Sequence handle your descriptions for you.
[USER=467]@John Evers[/USER] curious how that works.
I was thinking about this the other day in an area of scrub and trees following a fence.
I placed my 2 metre pole on top of post, data recorder in hand, staff bubble on bottom of pole.
Wondered how I'd do that with one if these units?
Richard,
There are several options if you must elevate.
If I am just locating the fence, I would normally not shoot the line posts, as I would normally be more interested in locating the actual fence wire which is actually at the side of a line post.
If you must elevate, a shot can be set to start with a time delay. The built in flash light will indicate that the shot is beginning, and completed. Pull it down, analyze the information on the display, and accept.
You can also use a cheap tablet if you desire, for full remote control and display, and you can even pretend that the tablet is the actual data collector. Doing this, you could put the LS on any height pole you desire, and it would be exactly like what you are currently doing.
Set it to take a shot "when lifted" and stop "when tilted". It is basically just when the pole becomes stationary and when it moves again is when it starts taking a shot and when it stops. It works very well for topo.
If you do not use time delay, but you tell it to reject shots that are too far off, then as you lift it, it will exceed this amount. Then, it will start when it gets up there.
N
matt8200, post: 350460, member: 6878 wrote: I find this makes it a more ergonomic design to operate and input data as it doesn't require the user to hunch over to operate and input data. I know in the past, I have found using a traditional data collector will cause my neck to become sore after a long day of stakeout work, this is not the case with the LS.
I just read that having your head bent forward and looking downward for long periods of time when using a smartphone or in our case, a traditional data collector, can lead to spinal problems. See the article in the Washington Post: Û÷Text neckÛª is becoming an Û÷epidemicÛª and could wreck your spine
Richard, post: 350491, member: 833 wrote: [USER=467]@John Evers[/USER] curious how that works.
I was thinking about this the other day in an area of scrub and trees following a fence.
I placed my 2 metre pole on top of post, data recorder in hand, staff bubble on bottom of pole.
Wondered how I'd do that with one if these units?
Can I answer that? OK, thanks!
Let's start at the beginning. You have your GPS antenna on the top of a 2 meter pole. You have a bubble down at the bottom of it. You are somehow managing to place the bottom of that 2m pole on TOP of a fence post. You are desiring a coord on TOP of this fencepost?
Ok, And, this 2m+fencepost tall is to get the GPS antenna up there, where there is LESS multipath, enough sky view, to get the shot. Because your unit does not work very well in a multipath environment?
There are many ways to skin this cat. How important is this shot? Is within 3' good enough? What if your GPS gave you a bad init?
Here is a workflow, with a JAVAD unit.
I use a 12' HIXON pole, with a SECO bipod. Having a taller rod, enables me to get shots in dense forest, faster. (Faster, easier, Faster easier)
I'd leave the pole down at 6', and get it all set for the shot, (Albeit 0.3' from the fence) Get the Javad unit all ready, maybe a 10" delay shot. Press the U-1 button (Resets the 6 GPS engines) Run it up to 10' tall. Study it for a moment, and then LEAN the pole into the fence, ESTIMATING the 0.30 offset. It would often be DONE in 30" to a minute. VERIFIED. (depends on how dense the sky cover it) I'd have a shot, that I could pretty well count on being within a tenth, or two.
BUT that is not all. It is the CONFIDENCE level that is so sweet with the Javad, with V-6 verify. It is still GPS. It will come back to earth, (back from being 10' tall) with a little square box, telling me the spread of shots, that were averaged into the final position. So, that box MAY tell me it was a shot within 0.17'. And, I wobbled a little, and I estimated the lean into the fence. Shot could be 0.2' off. BUT I am SURE it is not 6' off.
And, that is why I like the Javad.
I can live with a 0.3' error, (All errors combined) on a fence shot like that. I cannot live with a error of 6 feet.
O nevermind, go buy a New T10. I don't work for Javad!
🙂
Happy new year!
Nate
Nate isn't that little 1" box, just telling you your precision?
The entire "blob" of shots could be shifted due to multipath could it not?
I understand the software has routines to attempt to detect a shift and it probably works very well.
It's still a precision indicator right?
The "Blob" is telling you a sanctified report, on ONE bucket of shots.
It sits there, and WHEN a shot lands 6 feet away, it STARTS another bucket. Starts storing shots in this bucket number 2. Then, another shot 6' the other way, starts another bucket.
AFTER it gets up to 10 buckets going (real bad multipath environment) then it either throws things all out, and starts over, or it picks one, that is STATISTICALLY more sound, than the others. Lets it fill. and THAT is the box we see. THEN at the end of that shot, if throws everything out, and starts over. (This is the verify thing) if things are ok, then this is the shot you get. IF not, this one also gets thrown out, and it starts over. This is sort of like a casino, that only has to have a 3-5% win rate, (Or something like that) for the house, and they will make money, because in the long haul, they will bring money in. However, the Javad works with a BETTER number system than that.... maybe 90% win rate. So, it statistically fills one bucket of coords FASTER than the others. Then, after filling a bucket, and statistically averaging them, based on RMS etc. Then it kicks back, to see which bucket fills fastest, again. This is verify. After it verifies it, we are done. And, it all happens real fast, due to the 5 hz rate. (Everything is running at 5 hz) not just part of it. The radio is actually doing 5 hz. So, it's like watching an indy 500. touch the brakes, and they glow!
🙂
thanks for asking!
When I can't see something or can't set on something, I will get a shot 5å±ft one side of and then 5å±ft the other side of and the object will be in the middle of those two shots.
0.02
Good idea!
I have offset some random dist, and the pt desc reads NE 22.23' to pipe. (Pt No 750)
then, leave the pole.
Walk back some 50', with plumb bob. I-ball the pipe, and pole, set the bob. (Pt 751)
Move the pole. The pt dsc is LN 22.63' (That means I have the dist between the two shots, to compare with an inverse) This helps to check things.
And, now I use the traverse routine, to compute the pipe,
Inst at 750, BS 751, fs 752 Ang 180å¡ 22.23ft Fd 1" pipe in NS fnc, 1.2' N to Fc N-S-E
The dist is then inversed between 750 & 751 to see what it is like. Usually it is within 5-6 hundredths. (That is with my old Topcon system) I have not had my new system very long.
N
normally (is that a surveying qualification?) where I want a bit of precision I take 2 or three offsets at rotating around the object, and calculate point then stake point just to compare direct distance from GPS.
This case I would have involved climbing back and forth over an offset electric fence (two fences in effect) on a steep slope. That wasn't my preferred option in this instance.
Far quicker to put the pole on the post as it was then above the skyline of obstructions and quick to get a fix.
I'd very much like to see your devices in action in the real world of surveying.
I can see it could be a really useful addition to the survey arsenal of measuring devices.
I don't know how, but I'd suggest, that you go and spend 2 days in the field with the equipment, with somebody that knows HOW to run it. Then, spend another 1/2 day in the office, understanding WHY it is set up that way. Several other things to keep in mind, is that it gets updated very often, and it potentially can become the standard for gps, if they get the REST of the software going... fluently!
It works now, but it will become faster, and more intuitive.
N
A Harris, post: 350885, member: 81 wrote: When I can't see something or can't set on something, I will get a shot 5å±ft one side of and then 5å±ft the other side of and the object will be in the middle of those two shots.
0.02
Not a good idea... Shots should be at å±90å¡ angles
Jim in AZ, post: 350991, member: 249 wrote: Not a good idea... Shots should be at å±90å¡ angles
I hate to veer off topic, but...I prefer straight-line offset to 90 degree offsets.
With straight-line: if I'm off .02 at one end; i'm only off .01 at the center (the fip)
With 90 degree: if I'm off .02 at one offset; I'm off .02 at the center (the fip)
