Recent in accuracies...

[Nate The Surveyor]

Update: I went out last night, (there was nearly no breeze) and set up that pole, near a tree branch. And, meddled with it. All I could get out of it was about 0.05' of max wiggle. Its a good pole. The pole can go to 25 feet. I had it only extended to 15.2', using the larger parts of the tube. This makes a quite stiff, and stable setup.
Whatever it was, it was not a wiggley pole. Although, that was a very good guess.
I'm thinking of setting it out, in another location, but with the tall base again, to test it, and see if I can get it to repeat. Maybe all night, with auto store running, and then repeat up on that mountain. It'd probably be safe unattended, but I'd probably want to camp with it.
Since no one else has reported this kind of behavior, I think it is unique to the site.
Either tall pole,
Or electrical interference,
Or the 2 together, possibly related to the tall pole, acting as an RF collector, and interfering.
I might even go for a day, Or 1/2 day, and set the base on a tripod, And see if it still does it.
But, I'd like to check my shots with base to rover processing first. But, that's out of commission for now...
It tends to shake you, when things that you count on, break.
N

 

[Sean Joyce]

Great description Sean of a job that really shows just how versatile the Javad equipment really is!! RTK, then RTN, then back to base radio and collect PPK. Just nothing else out there with that kind of versatility.

Darren;
My thoughts exactly about versatility when I was doing the survey. The only capability that I would like to see added (and I don't know if it is possible)is the ability to pick points processing against a different base in the same session, since we could find ourselves needing to use different modes to communicate on a survey (radio or internet) to get our RTK corrections.

 

[Nate The Surveyor]

As we discussed this, being up on the top of a mountain, puts you in the path of loads of RF. putting it up 15.2', up on the mountain, obviously puts the t2 in the path of lots of things. Cell towers and all.
And, it could be time of day dependant. Ie, not behave the same at night, as it does during day.
So,
This leads to the question, how much multipath mitigation can the T2 handle?
Another way to say it, is would that t2 Be better off closer to the ground, even though that gives more multipath?

And, I see using the top of a car for a mounting place.... Effectively giving the T2 a serious ground plane.
Would the T2 work better, with a ground plane disk under it, up on that 15.2' pole?
Whatever the case may be, I want to wait til base to rover processing works, before continuing testing. Any suggestions would be appreciated.
N

 

[Matt Johnson]

As we discussed this, being up on the top of a mountain, puts you in the path of loads of RF. putting it up 15.2', up on the mountain, obviously puts the t2 in the path of lots of things. Cell towers and all.
And, it could be time of day dependant. Ie, not behave the same at night, as it does during day.
So,
This leads to the question, how much multipath mitigation can the T2 handle?
Another way to say it, is would that t2 Be better off closer to the ground, even though that gives more multipath?

And, I see using the top of a car for a mounting place.... Effectively giving the T2 a serious ground plane.
Would the T2 work better, with a ground plane disk under it, up on that 15.2' pole?
Whatever the case may be, I want to wait til base to rover processing works, before continuing testing. Any suggestions would be appreciated.
N

GNSS signals use right hand circular polarization, when they are reflected off an object including the ground, the reflected multipath signals are left handed polarized. GNSS antennas are designed to mitigate the left handed polarized signals. The further from the ground the antenna is, the weaker the multipath signals. Multipath introduces error in a sin wave type period. The closer to the ground the antenna is, the greater the frequency of this sin wave patterned error and the less time it takes to average out this error. Raising the antenna reduces the amount of multipath but increases the time it takes to average out the induced error in the position from any remaining multipath.

I would expect to see the vertical error about twice that of the horizontal error if multipath or interference was your problem. I think you said the vertical results are good so it seems that the antenna is moving around horizontally between shots.

 

[Wes Cole]

It would have been even better if all the static data I collected on the 2 points against the NYRTN base could somehow be processed, at least with CORS.

This would be a great feature! Hope to see it implemented in the future.

 

[Sean Joyce]

[
I'm telling you every thing I can think of that could cause problems. The horizontal dithering seemed to be a constant problem on this job.


Nate;
Not making light of this but the T-2 looks like a nice place for a bird to land on and hang out for a while.
Any "evidence" of that around your point.
I have had them land on my radio and stay for a while.

 

[Adam]

[
I'm telling you every thing I can think of that could cause problems. The horizontal dithering seemed to be a constant problem on this job.


Nate;
Not making light of this but the T-2 looks like a nice place for a bird to land on and hang out for a while.
Any "evidence" of that around your point.
I have had them land on my radio and stay for a while.

This is very possible, I watched a bird pirched on my T2 for about 15 minutes one day.

 

[Nate The Surveyor]

That's possible. Butt, no "Signs". I wonder how much that could affect it? I suspect simple radio interference.
N

 

[Nate The Surveyor]

Matt, Elevations were going up and down, 1 foot, 1/2 foot. Bouncing around.
N

 

[Matt Johnson]

That's possible. Butt, no "Signs". I wonder how much that could affect it? I suspect simple radio interference.
N

For interference to occur the source of interference would need to be broadcasting at or near the same frequency as the GNSS spectrum. Cell phone towers use 824-896 MHz and 1850-1990 MHz in the US which aren't near the GNSS frequencies but if you would post the screenshot or attach the project archive we could see the interference levels

 

[Nate The Surveyor]

If you set up your radio, turn it on, THEN run a radio scan, from 20 ft away, it will show interference, on all channels.
This is due to proximity of the RF source.
I got a call, from a local surveyor, who read this thread, who told me that these rural, Arkansas cell towers, are not "cable fed" but are "microwave fed". Meaning, that if you are near a tower, and the "horn" of the microwave device is aimed your direction, (there are 2 towers on this mountain, and my base was directly between them) then, for these 2 towers to communicate, it is probable that I was getting bleed over, from the towers, microwave communication devices.
I know my base was stable, and wind was not a factor. I looked at the verticals, and they were wobbling 0.5 ft to a foot.
Which fits the old adage, that error in verticals are roughly 3x the horizontal.
It kind of shook me up, to find these errors.... But I suspect that these problems will go away, after I move my base to another location.
I don't yet know how to use a Google drive, and the file is 72 mb.
But, I plan to take the LS back up there, to perform a "spectrum analysis". I can post screen shots of that.
The lesson learned, is to use the spectrum analyzer, if I'm in an area that could have RF. I even heard of a surveyor, who set his base near an air conditioner, which was giving all kinds of RF.
I hope my experiences save somebody else some trouble.
Back in the 1840's +-, when the original surveys were run, we did not have all this trouble with RF! (Grin)
Thanks for all the suggestions.
I'll post back screen shots of the RF, from the spectrum analysis scans.
Nate

 

[Nate The Surveyor]

I sent the file glenwood LS 2016 into the development team to try to figure out why base to Rover processing was not functioning thank you
Nate

 

[Darren Clemons]

Nate, if you don't have a gmail account go to www.google.com and create one. Once you do, you will have 15gb of storage available on google drive
https://www.google.com/drive/
Once you get there just click on "new" and upload your file or folder.
Once the file or folder is uploaded, right click on it and click "share".
Then you can type in anyone's email you'd like to send the link to to open or view the files.

 

[Nate The Surveyor]

When I click "ReDpos", then "Re-Send to Dpos" it waits about 15 seconds, thin CHING, Like it's done, but Still I cannot see any iteration, except RTK.
For the whole session, shot in with 97 as the base.
N

 

[Sean Joyce]

If you set up your radio, turn it on, THEN run a radio scan, from 20 ft away, it will show interference, on all channels.
This is due to proximity of the RF source.
I got a call, from a local surveyor, who read this thread, who told me that these rural, Arkansas cell towers, are not "cable fed" but are "microwave fed". Meaning, that if you are near a tower, and the "horn" of the microwave device is aimed your direction, (there are 2 towers on this mountain, and my base was directly between them) then, for these 2 towers to communicate, it is probable that I was getting bleed over, from the towers, microwave communication devices.
I know my base was stable, and wind was not a factor. I looked at the verticals, and they were wobbling 0.5 ft to a foot.
Which fits the old adage, that error in verticals are roughly 3x the horizontal.
It kind of shook me up, to find these errors.... But I suspect that these problems will go away, after I move my base to another location.
I don't yet know how to use a Google drive, and the file is 72 mb.
But, I plan to take the LS back up there, to perform a "spectrum analysis". I can post screen shots of that.
The lesson learned, is to use the spectrum analyzer, if I'm in an area that could have RF. I even heard of a surveyor, who set his base near an air conditioner, which was giving all kinds of RF.
I hope my experiences save somebody else some trouble.
Back in the 1840's +-, when the original surveys were run, we did not have all this trouble with RF! (Grin)
Thanks for all the suggestions.
I'll post back screen shots of the RF, from the spectrum analysis scans.
Nate

 

[Nate The Surveyor]

OK, I went and got some "Interference Spectrum" shots

And, a battery shot. The LS was quite hot. Well, and batteries were pulling low too.
Still cannot get ppk working. I forced a reload of Jfield this morning, and retried the Re-Dpos.
thanks

N

 

[Sean Joyce]

Sorry about the errant post.
Nate do you think the microwaves are the cause of your troubles?
They can cause a lot of interference.

 

[Nate The Surveyor]

Not a problem. I think that somebody more familiar with my "Interference Spectrum" shots, could comment. Things that cross my mind, is that interference can come, and go, due to changes at the towers. That is, you could set up, and all is good, and clean. Work for an hr, and suddenly the cell tower does another thing, in it's cycles, or ability, and now it meddles with things, for a while, and stops.
So, my feeling is "Keep your base away from cell towers". But, there will be times this is not possible. So, we need to know how to read these interference spectrum shots. And, if we suspect interference, we should be able to use are read these shots.

We live in an electronic world....

N

 

[Matt Johnson]

Nate, your screenshots are not showing abnormal interference. If you look at the screenshots of the points you could see the inference levels while the points were being collected.

 

[Nate The Surveyor]

Thanks Matt. I don't know what those are supposed to be like...
I got a feeling that whatever it was... It was not consistently doing it. That it was intermitant.
How do you "ctrl click", on the LS, to select muliple files? Ie, to copy them over to a thumb drive?
Thanks for the reply.


N