Permanent GPS base

we put the top part of an old prism pole in a pipe we set in the ground in concrete. we drilled holes through it and put wire in the holes. we then filled the pipe with concrete. it's remained incredibly stable for over a decade. you could probably accomplish the same thing with all-thread or a long bolt (maybe a foot long), putting some washers and nuts at the end to help anchor it to the concrete.

I would recommend using a brass bolt and pipe thread tape for any long term setup.

I have a steel threaded pole that has been together since 1974 and cannot separate without damaging.

0.02

I have seen several that are 300-400mm diameter pvc pipe stood vertically and filled with concrete.

They obviously have an appropriate amount to concrete and reo bars in them and their base to stop movement and a threaded fitting mounted in the concrete at the top for the antenna.

Here's a pic of an X90-OPUS receiver on the "POST"

A somewhat unattractive shot of the top of our "POST". This is a picture of the x90-OPUS receiver that I reviewed in this month's American Surveyor Magazine

American Surveyor Magazine: X90-OPUS Review

This is overkill but you may want to use the Ohio DOT CORS example as a model. The link is to a 2004 Professional Surveyor article.

I should clarify, the point is permanent but we won't always have a GPS receiver on it. We will just setup on it when working in town. As far as depth goes, as far down as we can dig with post hole diggers, 4 feet or a little more if we are lucky.

The threads are 5/8" x 11, the same as a typical bolt of that size. Get one in stainless. Cast it into a concrete post sunk below frost level, using a sonotube from Home Depot. If you want a little cleaner look use a 3" steel pipe for the form.

Here is one in Wyoming that I use for the month of June every year.

The 2' wide hole extends 7' to bedrock, 2" steel pipe in center is sitting on bedrock, the hole, 10" PVC and 2" pipe are all filled with concrete.

We pull the SECO adapter off and put a plastic cap on the PVC pipe when we are not using it. The trick is to spray WD40 all over the pipe so the threads stay un-rusty on the 2" NPT.

We have been using it since 2008. Seems to be okay. Bought everything at Ace Hardware in Rapid City for less than $150.

We have three rovers and check in every day and evening for the month. Everything seems to be a-ok.

M

Wouldn't work for long term, but on sites where I have to set up a base for machine control I set an 8' long 3" dia. Chain link fence post 3' deep with quickcrete around it. Then take an 8" long 5/8" bolt with a nut and lock nut that leaves just enough thread exposed to screw on the antenna and use a couple of radiator clamps to clamp it on the top of the post after its set. Then spray it with some orange paint so you can tell if its been messed with.

Having installed almost 500 GNSS Reference stations globally in my career, there are all sorts of really good designs out there. Some are ground based installations consisting of "Pour-in-Place" concrete pillars with structural rebar and built in Lightning protection systems. Some are building mount designs with Lightning suppression kits. I have seen the good, the bad and ugly GNSS Reference Station installations.

The best accessory is the SECO Adjustable Tilt Monument Mounts for Male 5/8 x 11 TPI
2072-33

http://www.surveying.com/Products/GPS-and-GNSS-Survey-Accessories/Monument-Adapters/2072-33

If you need to install > remove re-install your GNSS Reference Station Antenna periodically, the SECO Adjustable Tilt Monument Mount is the ticket, pretty much gets the GNSS antenna back into the same position each/every time, plumb + level >> orientated to True North. A quick check with your RTK Rover equipment to aknown Control point is the reality test.

NOAA/NGS has a PDF > Guidelines for Establishing and Operating CORS. A great reference PDF, maybe too much, too expensive to adhere to the NGS Specification for most guys, but never the less > a great reference document.

http://www.ngs.noaa.gov/CORS/Establish_Operate_CORS.shtml

Just my two cents...
-BbB B-)

This is the standard that we use.

Jeez,

That's more than a quarter mile tall. Who's the lucky guy that gets to put the antenna on it?:snarky:

I'll bet the range is tremendous.

JA, PLS SoCal

haha, well we use millimeters 😛

What is the benefit of the concrete filled pipe inside the PVC pipe, with the void also filled with concrete?

How is this better than the sonotube or just a larger concrete filled steel pipe?

Ken

Here is one I built on my property. Used for GPS and for testing EDM, prisms, etc. You can see the companion in the background near the barn (for EDM testing).

I really like your ability to just put a cap on top of that when not in use. Will protect the threads, and give the birds something to land on besides the top of your mount. If I ever have to build one, this is exactly what I am going to use. You could even make it shorter, and screw a range pole to it to get some height.

Make a setup like this one, paint the PVC green and don't give it a second thought!

Funny, I have never been there when the wind was not blowing at least 30 MPH. But it would make a great bird stand.

The most violent lightning/thunder storm I have ever seen blew through there one day and I had to run like the devil to drop the radio antenna down on the ground.

I can't imagine how horrible the weather would be right now.

I forgot to mention that it works out better if you can get some young kids to dig the hole. 😀

M

As I understand the thinking:

When the sun rises it heats up the eastern side of the steel pipe. But the west side is still cool. Repeats in reverse in the evening. We might see extremes of 50 deg F at night to 115 deg F at 2:00 pm. The pipe can get dang hot on one side. There might be 5 mm of side to side motion at the top.

I have been told that an unfilled PVC pipe breaks the radiant heating and the pipe stays the same temperature on both sides as it uniformly heats and cools.

Filling the PVC pipe makes it MUCH stiffer. If you push on the top of the 2" steel pipe (left or right) with your index finger, it will move 1 cm. If you fill the void between the steel pipe and the PVC, it does not move much.

We fill the inside of the pipe ALL THE WAY to the top (and even put a little hump on the top) so no water will get in the pipe. If water gets in the pipe, it will freeze and the steel pipe will split, the outside PVC pipe will split and then the concrete will break off. And then you won't have much.

At that monument I posted above, it routinely is -35 deg F at night in the winter. (Without windchill.)

We have toyed with the idea of putting a CORS station there (we have dependable 5 Meg symmetric internet with a radio link back to Gillette). But it has been my experience that an unattended CORS station there would be a nightmare to keep running (Solar powered to start off with.) I don't need anymore stuff with batteries in places that it takes 3 hours to hike to in the winter.

M

Here is the semi permanent base most days i just place the box on a
top of a trailer or pile of earth.

Very seldom set over a point usually push a couple of spikes into the ground and place the corners of the box on the spikes with the door facing north in summer and use the door in the winter to keep the head a little warmer. Then do the HERE "carlson speak" and localize and the usual grid or ground and check into various formal control points but usually only hold one vert and hor

A large pile of earth the base sat on the ground and did not move for 6 - 8 months
i usually only set a post if the base head is there for greater than 6 months or more.

Now use a plastic dish instead of the white palstic wrap in the photo above
held in place by velcro

As the can see the unit sits under its own weight on to of the top soil pile on site
that the paint is starting to fall off after two years in the rain sun. The office desk can be a post or pile of dirt it does not matter much. On most weekends i just leave the base house on top of a pile of dirt on the ground and its there on monday
just have to put in a fresh batt and im good for two days.

If you want a autocad of pdf of the drawing please email i will send and it should work for any GPS head just have to cut the right hole to fit the model you have.
and a little coax for the antenna.