Something I want my RTK GPS to do

> Lee,
>
> You are right on.
>
> That's exactly what I'm up to!
>
> N

If it is only a half mile, why not set up the base on known control at the old site?

1

I'm using TDS.

Here is what I am TRYING to do:

I am on my 2010 job base, and I select another good location for a base, and take 3 observations, or shots, on a point 2 miles away, in an open field. Each one is 5 mins + (that's what I like to do) They agree within 0.03' of each other.

I then take the middle one, and use it. Now, I have a new point, to use as a base. I can move up on it.
---------------------------------------------------

Fast foreward. to 2015. I want to do the SAME thing stated above, BUT I want to simply do it in reverse. Set base on NEW point, and work backwards, to ACCOMPLISH the same thing, but with the base and rover reversed. (This will work nicely in Static observations)

So, the sequence of events could also have a RE connect to base, before beginning the actual survey, to SEND the new Lat Lon into the base. Now, it has FULLY done the observation, with the base and rover reversed.

----------------------------------------------

I have thought of another mechanism.

Start a NEW job, on grid brngs, ground dist, at the new base site. Carefully re-observe several of the points on the old job, Including the old base site. (It is weighted heavier)

Write down the inverse between the old and the new base sites. And, the inverses between the new base site, and the old coord check shots.

Go back to the original job file, and use "Point in Direction, to make the new base coord, (also from several previously shot points) this gives you some idea of how well things are going, and checks for blunders)
Now, you have a new northing and easting for the new base site.
Restart the base, on the selected coordinate. Set the theta. Go back, and check the old base site. BUT this will result in a slightly different projection. Because the lat long is autonomous.

It would work, but it seems like a long way around, and not as efficient.

N

If it was me doing this, I would go back to the base and restart it from the new calculated coordinates before taking any shots on the new survey you are starting.

:good: :good:

I know it takes longer, but when you do it that way (restarting the base using the corrected numbers) you know in the field that everything is working together, there isn't a shift to "fix" things, I do it the same way.

What you need for base coordinates is the correct geodetic coordinate. OPUS is the easiest way to get them. It doesn't matter what projection (SPC. UTM,LDP) you are using to view the project. An RTK base broadcasts corrections calculated from the punched in geodetic coordinates you give it. As long as your base has the correct geodetic coordinates and the projections you use are centered on the correct geodetic coordinates it doesn't matter where your base is located. I can start a base in one file with a different projection and switch to another file with a different projection and it works just fine (as long as the base points you use have the correct geodetic coordinates). Staring a base with a HERE key and measuring over to a known coordinate and correcting for the HERE, doable but maybe not the best (accurate way) to do things.

Starting a base off a rover coordinate in an old job should work. After the base is started just switch to the new project coordinate system at the rover. The base coordinate will only be a good as the old coordinate was in relation to its base and quality of base coordinate.

Restart the base, on the selected coordinate. Set the theta. Go back, and check the old base site. BUT this will result in a slightly different projection. Because the lat long is autonomous.

I think you just about have it, you can work in the projection and the file you want to, you don't need to start another one with a different projection.

Like LRDay said Nate, it's the geodetic position that is critical to get correct. I understand what you're doing, I'm just not sure it's the best way to go about it. In a word, I'd post process as well as submit base data to OPUS. Don't rely on a 'on the fly' RTK solution or you might be chasing and compounding errors rather than corralling and minimizing them. Just my humble .02'.

Kent,

Like it or not, RTK is here. And, + - 0.10' is ok. And, you are outvoted. The realtors, and happy landowners outvoted you.

I'm not altogether happy about it.

But it's like that. I don't agree with alot in the world around me.

But, when you retire, your market niche will be sucked up by somebody with RTK.

Scary, huh?

N

I know it's not Halloween yet, or April fools, but BOO!

I am using a Sokkia GRX-1 base and rover with a network capable rover. When the GNSS signal is low or weak, or if I am going to be working in hills and hollows, I find a clear, open high point and use my Ranger with TDS Pro to connect to a network over the internal modem and put my rover unit on the two-meter tripod. I let it gin for 10-15 minutes while I unload my ATV and load it up with all my gear. By that time, there are enough "counts" (>500) to get the horizontaal accuracy number to less than 0.01 based on the network generated position. However I know that subsequent measurements to that same point at different times with my rover unit are typically 0.04 to 0.07 feet "off."

Next, I usually shut down the job, mount the base unit on the tripod and start the base on that now "known" point and collect data for OPUS comparison while I work. When I go to nearby jobs and re-shoot some of the control points for comparison, I see the same 0.04 to 0.07 foot differences.

For general topography location work, I can accept those numbers as good. For more critical points, such as corners found and control points, I use a method learned on this forum: multiple shots and different times of the day, and rotate the rod 180° between shots.

I use SPC for my work and resort to geodetic direction and ground distance for each job. I like the network capability in that I can be up and going in about 15 minutes. I have picked up a lot of good information here and appreciate the input others are willing to share.

I don't have any kind of local network to hook up with. OPUS is 50+ miles away.

I'm in Hot Springs.I use OPUS quite a bit. I don't usually have any trouble getting 9 or so CORS sites for an OPUS-RS solution. Even if you couldn't get that many CORS sites; you only need 3 for an OPUS-S solution.

How far is "a piece"/??// If it's close enough to get a "good" rtk shot, why not just set up on your original base there? leave a coon dog to guard the base station for 30 minutes while you set a new base on the new project.

I want my RTK to be a tap of nice cold beer at the end of a long day surveying the beaches of the Gulf of Mexico, but that doesn't happen, either!

He's is trying to save the setup time, since you get a vector between the two points it much quicker to recalculate the new point than set the base up twice. I've been "saving time" that way for quite a while now, lol

My base is a monster to move. And, sometimes there is stuff parked near the old base, or cows or whatever!

N

oh, I see. I'm thinking of my Hiper Pros... setup takes about 5 minutes. no wires.. no batteries, no external radio transmiter.

There are times when it isn't a good idea to use a base monument, horses in the pasture, cows, whatever. I will set the antenna on the top of the truck, the receiver and radio locked inside the truck, locate the base monument then recalc the receiver location and restart it as the base for the day. 😉

I usually give it a name like truck base or something so I know it's not over a monument.

Saves a lot of time over going back and finding my antenna wire chewed through and the tripod lying on the ground

Call it a One Point Nate Resection

There have been times I would have used it if it was available in Survey Controller.

James

Moe

Your solution scares the wee wee out of me. What do you do? Re-localize each time?

This means that your base is + - 0.05' each time. That's no big deal. BUT the rotation? Unless you are re-localizing on points out at the perimeter of your project, you can have a cannabis bearing system, (+ - one minute, or even maybe 10" or so, but you don't know. Insert "Best Regards here!") for each occupation. Now, I like you personally, but your method spooks me. OK?

N

Moe

What rotation Nate? Did you read what I posted above regarding localizations.

There should be no rotation.

Moe

IF I set a base on a point, and then shoot 4 points out 50' away from the base, then I ignore the base, and reset the base on a truck, and LOCALIZE on the 4 points, previously shot, then the new base coord will be pretty close. but, it's rotation will be a little off.

Hmmmm unless we are on SPC to start with....

Ok.

N