This thread was reactivated after almot nine full years. That shows how amazing SurveyorConnect has been for us. July 30, 2014 to June 25,2023. Incredible!
Edit: 2014 not 1914. That would have been pure science fiction.
Yea, them NOAA sites, I dont use them. Checked a couple months ago when I was near one and was only 1.9 feet out.
To be clear, are you saying that there are NGS CORS that are both active and 1.9 feet away from their current published position?
I'd be interested in how you managed to occupy a CORS that already has an antenna on it, especially considering many CORS positions are not physical monuments, but the antenna's ARP or L1/L2 position.
I know you think these stations are awesome, but I do not. I have had this discussion before with OPUS and EVERYONE thinks OPUS provides very accurate postions, I think not. It is a discussion that wont go anywhere. Oh yea really, I set my robot on CORS stations all the time. Have you ever verified a CORS determined position?
Have you ever verified a CORS determined position?
I’m at a loss as to how I’d verify a CORS position without using CORS data.
for the record, I have verified OPUS results by occupying passive marks. I’m happy with it.
This thread was reactivated after almot nine full years. That shows how amazing SurveyorConnect has been for us. July 30, 2014 to June 25,2023. Incredible!
Edit: 2014 not 1914. That would have been pure science fiction.
It was a great post until I got on it and it went downhill quick. By the way, that was my post in 1914. I just went by 'pacer' then.
I know you think these stations are awesome, but I do not. I have had this discussion before with OPUS and EVERYONE thinks OPUS provides very accurate postions, I think not. It is a discussion that wont go anywhere. Oh yea really, I set my robot on CORS stations all the time.
Show me a photo of your robot set up over an NGS CORS.
Remember, they typically look like this:
or this:
and the actual physical mark is often the bottom of the antenna, or the L1 phase center. How do you measure up from either one of those (with an instrument set up over the antenna, blocking antenna reception)?
Have you ever verified a CORS determined position?
We do, for somewhere between 30% and 50% of all projects. Pretty much anything where we are setting up more than a bare-bones control network, often where we are working for a big public-sector client and need to do more intensive QC/QA.
We process manually in TBC, we submit to OPUS-S or OPUS-RS, and we submit to Trimble's RTX-PP service as well. Three different checks, and in the case of RTX, a totally different processing methodology (PPP vs baseline processing) and totally different control station network.
We typically see about 1-5cm difference horizontally, and maybe 2-8cm vertical difference, between any two of the methods. Varies by site location and observation length.
Have you ever verified a CORS determined position?
I’m at a loss as to how I’d verify a CORS position without using CORS data.
for the record, I have verified OPUS results by occupying passive marks. I’m happy with it.
I do it all of the time, there is always a difference. 3 or 4 feet for a network (not Internet network) solution, half a foot for SBL. If you are happy with it, fine, that is not my complaint. Please consider that you are prepareing a solution with 80 mile base lines against a solution with 8 mile base lines. I dont want to argue with everone. I fully believe what my data tells me, what common geomerty dictates and what repeats itself over and over again.
The published coordinates for my local HARN points are normally within a centimeter horizontally when checked to CORS points.
Is that what you mean oldpacer?
I know you think these stations are awesome, but I do not. I have had this discussion before with OPUS and EVERYONE thinks OPUS provides very accurate postions, I think not. It is a discussion that wont go anywhere. Oh yea really, I set my robot on CORS stations all the time.
Show me a photo of your robot set up over an NGS CORS.
Remember, they typically look like this:
or this:
and the actual physical mark is often the bottom of the antenna, or the L1 phase center. How do you measure up from either one of those (with an instrument set up over the antenna, blocking antenna reception)?
Have you ever verified a CORS determined position?
We do, for somewhere between 30% and 50% of all projects. Pretty much anything where we are setting up more than a bare-bones control network, often where we are working for a big public-sector client and need to do more intensive QC/QA.
We process manually in TBC, we submit to OPUS-S or OPUS-RS, and we submit to Trimble's RTX-PP service as well. Three different checks, and in the case of RTX, a totally different processing methodology (PPP vs baseline processing) and totally different control station network.
We typically see about 1-5cm difference horizontally, and maybe 2-8cm vertical difference, between any two of the methods. Varies by site location and observation length.
I should not have baited you with the robot thing. I apologize, I, in no way, thought I would be taken literal on that. All of the procedures you listed are built on each other, they had better check with each other. Look, I am old, I do not do things the way you do things. I am not saying what you are doing is wrong or gets bad data. Your CORS stations may also be better than my CORS stations. I have a handful of full constellation receivers, I don’t mind working at night, I have good analytical software and good post processing software. I have a couple of full constellation super cheap Chinese receivers that I don’t mind to leave running all day and night. But based on your poor replies to my collection of autonomous positions, there is no need to go into my procedure. I am comfortable doing things the way I do in order to get the most precise data I can collect and translate that data into the most accurate position I can when the job requires more than 20 seconds of network corrected data. For me, hitting three CORS stations does not do that. Post processing CORS data does not do that, PPP with CORS data does not do that, I have not studied RTX, but maybe it would do that. Arguing this is like auguing OPUS or Trump, it is fruitless. I don’t mind discussing it, I have spent several hours today discussing this. You are not going to talk me down from Static and I am not going to talk you down from CORS. Please feel free to reply, but unless there is something new, I am done. At least until tomorrow. Good Luck.
@oldpacer is it possible the the way you use the term CORS is different than what most consider CORS. I define cors as NGS the agency either owned or have been cooped into ngs and those positions published via NGS. Now real time networks have permanent base stations that some call cors which is continuous operating stations. However they can have been entered into the ngs cors program and have a value published via nga but the broadcast another position for the real time network. As a matter of fact a vrs network or geo ++ network can have the same set of stTions but in the i trip casters depending on how they are set up be way different positions broadcast. I have had poor OPUS solutions verified on the ground but those are usually not the pages software’s problem it is a field procedure issue like not collecting long enough especially in poor site conditions. I have two right now on same point. One 4 hour waited a week sent off 98% and same point 1 hour sent that day utra rapid orbit. 70% ambg fixed. .35 ft Vertical difference same point. In not a good gps area. Also same monument verified from levels for vertical. Opus was not wrong on either it was purposely done by me to show and teach why just sending to opus is only half the battle. And why i require 4 hours sometimes and 2 hours sometimes. Because i plan and look at the NGS CORS stations and where they are in respect to my site and site conditions. Now my crews understand better. The one rapid ultra orbit and short collection time actually falls within the error estimates opus sais. I have no idea and am confused that you can state that autanoumous position is more accurate. If i read that wrong please correct me. As I personally did orbit determination for the gps satellites. Broadcast orbits are not that accurate. Rapid orbits get better precise ephemeris is the best. Because we get to tell the satellite or softwRe exactly where they were and at whT time they were there.
@oldpacer is it possible the the way you use the term CORS is different than what most consider CORS. I define cors as NGS the agency either owned or have been cooped into ngs and those positions published via NGS. Now real time networks have permanent base stations that some call cors which is continuous operating stations. However they can have been entered into the ngs cors program and have a value published via nga but the broadcast another position for the real time network. As a matter of fact a vrs network or geo ++ network can have the same set of stTions but in the i trip casters depending on how they are set up be way different positions broadcast. I have had poor OPUS solutions verified on the ground but those are usually not the pages software’s problem it is a field procedure issue like not collecting long enough especially in poor site conditions. I have two right now on same point. One 4 hour waited a week sent off 98% and same point 1 hour sent that day utra rapid orbit. 70% ambg fixed. .35 ft Vertical difference same point. In not a good gps area. Also same monument verified from levels for vertical. Opus was not wrong on either it was purposely done by me to show and teach why just sending to opus is only half the battle. And why i require 4 hours sometimes and 2 hours sometimes. Because i plan and look at the NGS CORS stations and where they are in respect to my site and site conditions. Now my crews understand better. The one rapid ultra orbit and short collection time actually falls within the error estimates opus sais. I have no idea and am confused that you can state that autanoumous position is more accurate. If i read that wrong please correct me. As I personally did orbit determination for the gps satellites. Broadcast orbits are not that accurate. Rapid orbits get better precise ephemeris is the best. Because we get to tell the satellite or softwRe exactly where they were and at whT time they were there.
NGS CORS, yes
4 hour OPUS, yes
On your automonous positions, How long were your sessions?
@oldpacer i don’t use autonomous positions for survey grade work maybe as a starting point. Ot a seed point that we did years ago for static. A here position to keep rtk relative base and rover until i can send a rinex file to opus for correction or process it against other static sessions known. A ppp position as i define it has no vectors or ties to any other station. It is an absolute position. Several 4 hour sessions up to 24 hours files over course of time to position something absolutely. I did a lot of this in the usmc and we did a lot at nga. For static work solving vectors. I use baseline lenth number of satellites tracked and accuracy needed to determine time. That was for true geodetic work i did. For control now days most of my projects on the Land Surveying side are not large sites. I use a method of a starting point with a VRS point set up base and rover next. Always log raw data at receiver for sending to opus. So not a lot of high accuracy stuff. I don’t always hold the vrs positions and i don’t always hold the opus. I know the network in my area through redundant checks to know where it works to get me on datum withen a reasonable tolerance and when it doesn’t. If rtk gps gnss only. For this area I usually exceed alta specs of the .07 ft + 50 ppm and i never locate a property corner or control with one vector. At minimum 2 and i have the base moved and 4 hrs difference in time. Sometimes it works we get 3 or 4 but i better have two observations that can have that gap in time that passes alta specs. Which passes my state specs as of now. But reality is i have more redundancy that just rtk for relative checks and I usually have more than one opus or vrs for my datum check i also usually most often because of canapy or othe influence that could cause issues with gnss use robot and cross tie traverse etc and build a good geometric figure with redundancy to incorporate all the data for a correctly weighted and minimum constrained usually constrained with uncertainty at one of the datum positions and perform least squares after i have eliminated as many blunders or bad vectors mean turned angles etc. I think i have not gone more than 3 miles usually less than that for most of our jobs relative. To ngs stations that could be up to 20 miles. To vrs around that or less depending on where i am within the state. I check that map daily for every job site as well. So my requirements i am handed dictate my approach. We had a job that we were asked to do. I looked at the requirements specs. Went to the boss went over it with him and he agreed its not worth it for us. We don’t have the tools to make it happen yet. Could i have achieved that accuracies they needed absolutely i had the confidence. Just we dont have a 1 second high end total station or robot nor a electronic level nor the other tools for alligng the tension on a swing bridge that needed something better than what my survey brain and toolbox had. I priced a laser tracker for rent and have used them. Cost vs profit was not where we needed to be. So i passed a name to my boss of a guy who i know and did nothing but laser tracker metrology measurements everyday. Client was happy. I was happy. I have not used one in several years and they can be more cantankerous than a old lady. Don’t tell my wife I said that
But based on your poor replies to my collection of autonomous positions, there is no need to go into my procedure.
Thanks, I needed a laugh after a rough workday.
Consider her to have been informed. Sorry, buddy.
"I have not used one in several years and they can be more cantankerous than a old lady. Don’t tell my wife I said that 
"
@olemanriverswife
@holy-cow I thought we were friends . Oh she keeps me straight. I am so good i have to plan on getting in trouble. I also have ocean front property in Arizona ….
Just because your boat dock is close to mine DOES NOT mean you are allowed to use it.
