GPS help???

1.) There is Post processed GPS. And, real time GPS,

2.) There is L-1 only. There is L-1 and L-2. Now there are a few more signals out there, with modern units.

3.) There are units, that require YOU to supply the BASE, and there are some cities, where you can pay and get your corrections from a cell connection.

4.) There is opus.

So, Stoner, you have to know your needs, to go ahead.

N

The job is pipeline construction, so layout and as-built or pipe locations. I'm thinking robotic total station might be better option. What is the accuracy and reliability of GPS.

Thank you for the help.

Well, Mr Stoner,

I know several things about this.

There is a point where you no longer own your equipment. The equipment owns you. That is, we all want a nice new tool in our tool bag, but the commitment level to ownership often exceeds our desire to learn. What this means is that there is alot to learn, before it can work efficiently, in our application.

For this task, you want RTK, with knowledge, and ability to move your base station, and easily work in State Plane coords, and easily convert to ground.

I honestly suggest you call around, and get yourself a local surveyor that knows how to use RTK GPS, SPC datums, and USE him to do your first project.

There is so much to learn, it is really mind boggling. When I bought, I hired a local RTK guy for several days. Learned alot. Then, after buying, I got help from another surveyor, who did not understand projections, and their applied use. He did all in TRUE from the base, and had to ROTATE from each base station, to get the bearings all to be on the same datum. He asked me why each base setup was on a new brg system. He did not know. And had owned it for maybe 5+ yrs, doing pipeline work!!

Are you a PLS, or a field hand? What do you know, and where are you coming from?

N

I am not a PLS, I have been doing construction surveying for 10 years. I have been mentored by PLS's and SIT's. I am currently a party chief/ 1 man crew for a construction company which is going out of business. I am in the process of taking job with different company which has pipeline job. I am knowledgeable in the fundementals of surveying, bearings, coordinates, datums.

I am assuming the base station must have a known horizontal and vertical location and must also be oriented to a specific bearing. Then triangulates to the roving device to determine the real time loaction??

Do you suggest any books on GPS theory?

>
> Do you suggest any books on GPS theory?

Aloha, Stoner1826:
This book was suggested in several old posts.
GPS for Land Surveyors by Jan Van Sickle. It is available on Amazon.com

Aloha

>
> Do you suggest any books on GPS theory?

Jan Van Sickle's book is probably the best for introductory level, does a good job of explaining GPS for land surveyors and introduces you to the associated Geodesy without getting into the higher math. Pretty concisely written with a lot of how to field procedure type of stuff.

Click on the link

GPS for Land Surveyors

> I am not a PLS, I have been doing construction surveying for 10 years. I have been mentored by PLS's and SIT's. I am currently a party chief/ 1 man crew for a construction company which is going out of business. I am in the process of taking job with different company which has pipeline job. I am knowledgeable in the fundementals of surveying, bearings, coordinates, datums.
>
> I am assuming the base station must have a known horizontal and vertical location and must also be oriented to a specific bearing. Then triangulates to the roving device to determine the real time loaction??
>
> Do you suggest any books on GPS theory?

First of all I have very limited experience with GPS. Given that statement I do know enough to say that your assumption above is about half correct. The computations are based on signal travel time from several GPS satellites. The satellites "know" their location and transmit it and a time signal. The base SHOULD have known location. However each GPS unit computes a current location at regular intervals. Triangulation between base and rovers is not involved. The base compares the computed location with the known and transmits a correction to the rover units. The rovers apply the correction in real time to give your rover a corrected location.

ALL OF THIS IS A VERY SIMPLIFIED OVERVIEW.

As for a text "GPS for Land Surveyors, Third Edition" by Jan Van Sickle is widely recommended. I am sure other posters here will correct my errors and recommend other resources.

> The job is pipeline construction, so layout and as-built or pipe locations. I'm thinking robotic total station might be better option. What is the accuracy and reliability of GPS.
>
> Thank you for the help.

If you are asking the above statement, you have a lot more to learn than just how to use GPS.

I was stating the work will be layout and as-built of pipe locations. Only question was on the accuracy and reliability of GPS. Ive heard GPS can be a hassle if there is any tree cover and that the vertical isnt very good which is very important for pipe work. My opinion is a robotic total station will most likely be best option. I am pretty sure I can choose what how I do the work.

> .... the vertical isnt very good which is very important for pipe work.
These petroleum pipelines are pressure vessels. The elevation is not so very critical.

> ...My opinion is a robotic total station will most likely be best option. I am pretty sure I can choose what how I do the work.
Until you have worked on the day on the job, and until you have learned how to use the equipment, maybe you better keep your opinions under your hat. You will be laughed off the job if you insist on using a robot. Your job site is going to span miles.

Sometimes you've got to hit the books and study before you even know what the right questions to ask are. I think that's where you are. No shame in it. Everyone started at the beginning. Best to be honest with yourself and prospective employers about what you know. Don't try to bs your way through.

Exactly why I posted here. I don't know what I don't know. I am new to pipeline work and GPS. I ordered the book that was suggested. I don't understand why guys get so bent outta shape when someone doesn't know something, I think of it as we are ALL on a journey as surveyors. We are all at a certain spot of the journey, right now my position in the journey is a lot farther back than most of you, I'm ahead of others. But we are all on the same journey.

Thanks for the help I appreciate it greatly!

> Exactly why I posted here. I don't know what I don't know. I am new to pipeline work and GPS. I ordered the book that was suggested. I don't understand why guys get so bent outta shape when someone doesn't know something, I think of it as we are ALL on a journey as surveyors. We are all at a certain spot of the journey, right now my position in the journey is a lot farther back than most of you, I'm ahead of others. But we are all on the same journey.
>
> Thanks for the help I appreciate it greatly!

Don't let the negative vibes bother you. Many of us here are nearing the other end of that journey. We have become very careful about answering questions like yours. There are way more "button pushers" and "expert measurers" out there than thinking surveyors. They learn the technology and leave out the critical question "Should I believe the answer this magic black box just gave me?"

Many can not tell if a total station or level is out of adjustment. If it appears to work they accept the result as correct. We have cleaned up after these and try to encourage learning the critical thinking before the technology. That usually results in a better product.

depending how and what GPS devices are being used, GPS can be very accurate. know what hardware and software you need and is it flexible enough to work on different projects you'll be on in the future.
rent or buy 2 used receivers (1 base station and 1 rover.) and just as important are the antennas, 1 or 2 geodetic and/or 1 rover antenna. buy the used controllers for each device and the controller software for each controller. and get the software for your PC. take the hardware and controllers out somewhere, a park or in the boonies and start testing and learning. and read that book. spend time reading posts on UNAVCO and other forums as such will help in understanding the hardware involved. knowing and understanding this hardware and staying ahead of the curve is an imperative. the more creative minded you are the better. you don't want to be a brain dead just turn it on and go type. personally i'd go with Trimble products because the software is intuitive and you don't have to this, that and the other thing to obtain a solution. I use Trimble and would never use anything else, it's expensive though. Ashtech, JAVAD or Novatel would be another choice and are just as good. get some Trimble R6's and/or R8's
You mentioned a concern about multipath (trees and buildings), you can get good measurements if you are patient, train yourself and get good offsets. if you have the flexibility you can post process today's data and offset the position at a later date. Many possible approaches, i can't tell you how, that's your job. i have colleagues, we all are after the same thing doing the same type of layouts and work, we all have different approaches customized and tailored out of our experiences and personalities.
in the open you'll get better than 1 cm resolution. mm's resolution. in high multipath and refracted signals, it depends, so many variables. in 150 foot tall timber with moderate canopy cover we typically get 1 to 4 cm resolution with a base setup with in a mile. better if the base is with in a 1/2 mile. depending on the quality and number of observations.
one thing to keep in mind about hardware are the bells and whistles, you don't need GLONASS to get good data, the imperative is you need good receivers and good antennas, close base stations and good offsets. and keep it simple. its not as complicated as it may appear or as it may be implied.
WHAT FUN!!

> I was stating the work will be layout and as-built of pipe locations. Only question was on the accuracy and reliability of GPS. Ive heard GPS can be a hassle if there is any tree cover and that the vertical isnt very good which is very important for pipe work. My opinion is a robotic total station will most likely be best option. I am pretty sure I can choose what how I do the work.

Re-reading my comments I guess they did come off as negative, however that wasn't the case. My comment came from hundreds of miles of pipeline experience and hundreds of thousands of acres being surveyed for oil and gas companies.

Yes, you can use whatever equipment you think will be right for the job, however the minute you can't keep up with x-ray or have to setup your robot every time a weld needs to be shot in before they bury the pipe you will be quickly be asked to leave and a new survey company will be out there the next day.

It's just the way it works out there. Plant/facility and pipeline work is not for the faint of heart and you either perform quickly, without mistake or they will find someone who will. In the grand scheme of things the survey bill is the cheapest thing. Wait till a contractor wants to start charging you standby time for a crane.

Sometimes I wonder if Kent posts these just to prove his point.

Is it possible that someone just posted a request for a full explanation of "GPS" technique?

This has to be a fake post.

Lot of good info here...

http://www.ngs.noaa.gov/PUBS_LIB/UserGuidelinesForSingleBaseRealTimeGNSSPositioningv.3.1APR2014-1.pdf

http://www.ngs.noaa.gov/PUBS_LIB/NGSGuidelinesForRealTimeGNSSNetworks.pdf

> Sometimes I wonder if Kent posts these just to prove his point.
>
> Is it possible that someone just posted a request for a full explanation of "GPS" technique?
>
> This has to be a fake post.

LOL! Not my work. Read it and weep. The great thing is that if the poster goes with RTK, he won't have to really know anything about GPS as long as the system is returning numbers, eh?

Thanks for the info. I did not ask for "full explanation" I asked for resources and guidance on where/how to learn about GPS. I really dont understand some guys. Were you born a master surveyor with license in hand? Why is it so hard to understand at one time you were exactly where I am now. I thought the point of belonging to a forum is to give and recieve information from others in the field, not to tell everyone how great you are and pathetic they are because they don't know everything you know.

But to those that do understand, thank you for the suggestions.