Static training

Ha. We could probably tell you how to do it on here is a couple paragraphs...

I'm all ears...or eyes I guess..

Joe
I'm assembling a class on TBC, which will include static processing, to be taught by Michael McInnis in January if you are interested but you probably need Topcon and TDS rather than TBC.
John

Static Training EASY, Just Don't Move

Paul in PA

SORRY!under wrong area/

Down the hyper manuals and read them. Basicly set up the receiver and collect data. Down load the data and post process the data. It will take some time to learn where you can push close to cover. You will need Topcon tools to process. You can download and process up to points in demo mode. You can use a CORS if one is close or OPUS. Do some search and reading on the net.

It's easy set up on your known points, then occupy your unknowns. We used Trimble our time was 2 mins per mile away from known points (Minimum was 10 mins). More vectors you have the better. Using opus will increase number of vectors and accuracy. Also if you have enough receivers we used to try to burn as many unknown points as possible. Going back getting 1st set up, setting it up on next point. You'll increase vectors this way also. example 1,2,3 are unknown. Let them burn..move 1 to 4, then 2 to 5, leaving others going. Then you'll have vectors from known, opus, and 2,3 when burning 4, etc.
Hope this made sense.

We had an instructor come up from "Topocon University" free within the company but outsiders could pay to sit in...well worth the cost.. maybe get something like that going...it was a 4 day class
heres a link http://www.topconuniversity.com/

OK, Joe, you set out 3 recievers, and place them into RECORD STATIC mode, whereby it then stores what it gets from the sats.

You must measure the Ant. Height above the point. Either Slant, or straight HI.

(That step can be omited, if elevation does not matter, AND if you are totally sure that a re-observation is not going to be)

Write down the start time, and stop time.

Set out all the recievers you have, and then take them home, and down load them, with TT.

Post process it, and see what you got.

Tell you PP software what you want for output, SPC, NAD 83, etc.

Get your scale factors, and then you will have it.

Nate

In GPS you must never neglect heights.

GPS is a 3D measuring system; heights are critical to a good solution. GPS is not a plane measuring system like your total station; it measures on the ellipsoid and the software converts the answers to the plane system of your choice.

If you use all 2 meter poles then I guess you could ignore heights except for the CORS you are tie-ing into or OPUS so I still enter the heights.

And if you are going to do conventional ties from your GPS observations and process it all in your network least squares software then you need heights there too.

In fact I always do everything 3D because it isn't that hard to do.

I took a 3 day TGO post processing class about 8 years ago and a 2 day RTK class at the same time.

You can measure one baseline if you want to.

Static is a very useful tool to have in your toolbox. I use it 90+% of the time when using GPS.

You set up as many receivers as you have or want on your points and have them collect a file. Keep good notes, point number, start time, stop time, type (static), which receiver, slant or ARP in meters and feet and description. I enter the height into the controller in meters (1.531M enter) and it converts to feet which I can compare to make sure I don't have a height blunder.

The processor generates 3D vectors from mon point to mon point and shows you what it thinks the accuracies are. You can also export that information to a file for your network least squares which will use the 3D vector and covariance matrix to adjust your network. Generally in Static you try to get a network but you can do a radial survey just like RTK (only better) if you want to.

One advantage of static is that you can get more than one vector into a point with a single obersvation. For example if you have three receivers running then you can get 2 vectors into a point. If you have 4 running then you can get three vectors into a point.

Just bear in mind that the three vectors share the same biases (such as multi-path) so you don't really have as much redundancy as you think.

Trimble used to teach that you can only use N (receivers) -1 baselines (Trimble speak for vector) per session (a session consists of your receivers running simultaneously on some points, when you move some or all receivers then you have a new session). They would say three receivers yields 2 baselines and 1 trivial baseline (you choose which is trivial) and it would take another session to close the loop with a 3rd vector. This is controversial because the processors generate each vector independently. I personally use all the vectors but just keep in mind that really tight loop closures may mask a problem with one of your network points. For example, if all of your vectors into that point are subject to the same multi-path error then you could have compensating errors making your loop closure look really good although the coordinate for that point is not good. Of course in RTK you can have the same thing, often with only one observation or the myth that you can just do 5 RTK observations in rapid succession which doesn't really do much but confirm a bad answer.

I think the Trimble way was a way to encourage you to get true redundancy into your network.

A loop closure is a routine where it takes all of your vectors and adds them up to see if they make a closed figure similar to a closed traverse. If you select all of your processed vectors in Topcon Tools and do a loop closure it will generate a list of all the possible closed figures in the network and how they fit together. It is a way to search out bad vectors.

Howdy,

I'd look at this

Document describing GPS surveys as performed by Aeronautical Surveys program of NGS

If link does not work, cut and paste text below:

http://www.ngs.noaa.gov/AERO/Genspecs_A/Volume%20A_Attachment%2011-19.pdf

Wow. People still do static.

Cheers,

DMM

dave

> In GPS you must never neglect heights.
>
> GPS is a 3D measuring system; heights are critical to a good solution. GPS is not a plane measuring system like your total station; it measures on the ellipsoid and the software converts the answers to the plane system of your choice.
>
> If you use all 2 meter poles then I guess you could ignore heights except for the CORS you are tie-ing into or OPUS so I still enter the heights."""

i agree dave, NEVER work without height of antenna.

GPS/GNSS computes on a Cartesian X,Y,Z frame. don't mistake the cartesian x/y/z for n/e/ortho(state grid) or lat/ lon/ ellip(WGS84). the xyz is an earth centered earth fixed reference frame that does not match origin exactly with, say, the origin of WGS84. we need to remind ourselves what this xyz frame looks like, and how it works to realize that the antenna height 'telegraphs' through these conversions of reference frames; and, consequently, how they will affect the data.

it is the field firmware or office software that converts locations to other reference frames, such as state grid, WGS84, among others.

maybe not working with an antenna height, the horizontal coordinate error will be small, maybe, but why flirt with that possibility? besides, you can get respectable ellipsoidal heights from proper care and procedures. compute the geoid separation and you have a decent ortho height, too.

note: other people, more expert than myself, such as shelby, loyal, geodd, mike mulcare, ddd, many others; can explain this more eloquently. this is my angle on things, i am having a hard time describing them. maybe it was the wedding reception last night that has me head in a fog.

A good friend (in spite of being an engineer) bit the bullet and paid for a 4 hour training session with the local Topcon rep to learn how to do static work and OPUS submissions with his Legacy system. He is a year veteran of RTK, and has a Cadillac system (wonder how that happened) so they were able to focus in on specifically what he needed to do differently from RTK. With a RAM upgrade, he can now do both simultaneously and is doing legacy updates to control.

He maintains it was money very well spent.

I was trained in about an hour (probably less) one morning at my first surveying company. I wrote copius notes in a little pocket field book I kept on me. I think that day was taking observations on the baseline at Shiflet Field in Marion, NC.
WE didn't know we going to do that that day. Nor, did I know what baby-sitting on a static setup was all about. From that day on I brought a book with me in case we got sent on another. Talk about boredom!!

About a year or so later we got sent out like that again. This time we had 4 of us with 3 static setups on a mountain. I was solo on my setup and had a helluva climb to my point. Knowing I had the climb ahead of me, I left all my stuff in the truck since I already was packing heavy with the equipment. It was freakin cold and windy that day. No radio communication or cell phones with my cohorts as we were told it might interfere with the receivers. I'm all alone on top this mountain wondering how I can entertain myself. Then it started snowing like hell. We were to do about 4 observations around 45 minutes each so I knew I'd be stuck there for a while. After a couple hours the party chief sent the spare 4th person to come check on me and my setup to be sure I was "doing it right". I think I was only on my 2nd or 3rd setup and it was snowing really good by then. About the time the girl showed up (yes, girl surveyor) to check on me I had made myself a bed, was sound a$$ asleep (probably snoring like a steam engine) and about half covered up with snow.

That's pretty much about my only experiences with static GPS.

John,

I have been looking around for some training on TBC myself. Do you have more information about the training you are putting together?

I may know of some other individuals in OR that would be interested in TBC training.

Please feel free to drop me an email:

kevin_r_samuel(at)yahoo.com

Respectfully,

Kevin Samuel, PLS

Kevin
I have been organizing these classes since GPSurvey and have continued through TGO and now TBC. Michael McInnis is a Trimble trainer and has authored user manuals for all three software packages(included with the class). The classes are somewhat informal in that attendees bring their questions and problems to be answered rather than Michael simply lecturing. One great thing about the class is that he stresses proper survey procedure and geodesy as well as specific elements of the software. I learn something every year as well as get reminders about stuff I had forgotten or do not very often. You can go to his website www.gpstraining.com for a more in depth review but keep in mind that this class is a little different because it is user driven. We usually have beginners to advanced users attending with over half the class being repeats. Last year we had people from Montana attending.
Also a great catered lunch is included.
We haven't set a firm date yet but are shooting for January probably in Albany.

Let me know if I can answer any questions.

John Minor

dave

> maybe not working with an antenna height, the horizontal coordinate error will be small, maybe, but why flirt with that possibility?

At normal antenna heights (e.g. 2 meters) the deflection of the vertical is submillimeter and thus lost in the noise of the baseline solution. GPS vectors are first computed antenna-to-antenna, and then dropped normal to the ellipsoid to get the ground station position; if horizontal position is all that's required, antenna heights can be ignored.

That said, there's rarely any compelling reason to do so.

dave

I agree if you use the same ARP height (for example 2 meters on a pole) at every setup.

But if you have redundant observations or a network of connections and use variable height setups (tripod) then not entering heights will cause problems with the least squares adjustment.

If CORS are used in the project they rarely sit on a 2 meter pole so will have a different height.

My original post may be misleading in that baseline processors reduce the baseline to mark to mark therefore a 3rd party LS software will not use the heights since the vectors are already reduced to ground level. This is different from the way they handle conventional observations which will use the HIs and THs in the line with the angles and distances.

dave

> But if you have redundant observations or a network of connections and use variable height setups (tripod) then not entering heights will cause problems with the least squares adjustment.

There are ways around that if horizontal position is all that's needed -- in Star*Net, for example, you could assign an alternate vertical scalar or increase the vertical centering error. I suppose that might be useful if you needed to salvage a day's work in which someone forgot to record antenna heights.

Since I very, very rarely use anything other than 2-meter tripods for GPS work, it's never been an issue for me.