I work for a small survey firm in Palm Beach County, FL and have been semi - put in charge of setting up a local RTK network for localizing our unit vertically and horizontally. Instead of hunting down state and county vertical and horizontal benchmarks, my firm would like to set up a network of it's own to check into for various jobs. Being a small firm we do not have all of the latest and greatest technology but have recently invested in a new Leica GS14. So far no complaints, and I feel I have a good handle on how to use it accurately and proficiently. I am curious though as to the procedures of the rest of the survey industry of how to gain accuracy and set up such a local network. Typically when doing a GPS survey, we will localize to the county points and rock n' roll, however given the nature of RTK with no base station to localize too, I often doubt the accuracy of simply localizing to the known points. My plan was to set a couple of points around town, shoot them various times for a given amount of time and correlate them to the known points. Any input on procedures from you guys that do this kind of work would be greatly appreciated!
Thanks,
Brian
Just to be clear, are you already using the FPRN? But you want to set up a system of control points in your area to localize to and check into?
It seems like flordia has a free cors network. Running annetwork rover would eliminate the need to localize as long as you are working in the same system the cors is broadcasting in. what are you trying to accomplish with the localization.
I would set two points right in front of your office and observe them with long (4 hour) OPUS observations to determine reasonably good positions. I'd then check in them at the beginning and end of each day.
I would not use them to "localize," as others have said this is unnecessary.. but I would use it as part of a QA/QC program.
Pseudo Ranger, yes we are a using the FPRN network and I understand how it works, we check into horizontal and vertical BMs around the area we would just like to create a local point network to eliminate discrepancies without having to search for county BMs (lazy way out!). Hardline, I like your idea, that was what I was originally planning to do, as well as doing this with other points around town close to our projects. Thank you all for you input.
McCracker,
No disrespect. But I'm not sure about your methods. By using a network RTK, there is no need for you to localize, as others have suggested. You will most likely create more error by localizing with RTK. Why do you feel so inclined to do this? If you stay on state plane coordinates you can check with OPUS, Static GPS, NGS markers, and other surveys. I would try very hard NOT to localize any control projects. Best to work on known projection. Best to use static GPS for control work. Suggest using 4 or more static receivers for simultaneous sessions. Add CORS into your static work. Then take data back to office for post processing and analyze it for yourself, to compare the differences from your RTK checks. I prefer to manually verify the differences.
Lee Green
No disrespect at all I am looking for this kind of input. As I previously stated we do not have the 4 receivers at our convenience and we do check into such knowns as NGS and other points.
Before people question his methods, I'm curious how much difference you are seeing vertically between your local benchmarks and the elevations you get from the FPRN?
I see about 0.20' difference pretty consistently between FPRN and our brand new county-wide 1st order bluebooked benchmarks, so I can see why someone would be tempted to localize for closer elevations. I don't use Network RTK for elevations, though, but if I did, rather than localizing, I would probably hit a few local benchmarks, calculate the average offset, then adjust the points in CAD to make them fit closer. If you do that often enough, you'll probably get an accurate picture of how far the FPRN is off in your region.
As others have said, localizing with network RTK will probably reduce some errors but also create some new distortions.
