One or two receivers?

Unless you use OPUS Projects for processing, with two receivers you would still get solutions at each with respect to the CORS and not each other. So by using an automated processing engine like OPUS, SCOUT, AUSPOS, CSRS-PPP, etc your two receivers will not be processed together. Using OPUS-Projects they would be. I doubt that you would ever want to create a network with only one receiver. Additional receivers add to efficient operation.

Get 2 receivers, or do it 2x for more strength.

OK, lets look at it. Suppose you set the receiver out for 4 hrs on one point, and get residuals of 0.05' in the northings, and 0.02' in the eastings.

Move it 1000' feet away, (Points are intervisable), and do another opus. Now, the Northings are the same for the previous point. (They won't be, but for my example they are.!)

Now, you have a total error potential, of 0.10' in the northings, and 0.04' in the eastings.

This would probably be acceptable, IF the points were close to north and south of each other.

BUT if they were EW of each other, then more sloppy.

Think in terms of a TRAVERSE from Point one, to the coors station, and back. Then, a traverse from point 2 to the coors station, and back. BUT no inter-visible tie. Like shooting with a total station 2 pts that were 5 feet apart, from a point 500 feet away. Would those 2 pts make a good basis of bearings? That is an exaggeration, but you get the point.

BUT if you occupied them and turned all angles, and distances, its strength of figure goes way up.

N

Post Process Yourself Against A Local CORS

That will tighten up your positions considerably. However, considering you have only one receiver you may not in fact have Post Processing Software.

Paul in PA

Post Process Yourself Against A Local CORS

What kind of a project/job is this for? Let's not overkill here.

Post Process Yourself Against A Local CORS

My typical project is a boundary in a rural area. My Board suggests that surveys be tied to the State Coordinate System although it is not a strict requirement. I was thinking that my two points observed in static mode and post processed through OPUS would give significantly accurate results for this purpose.

Post Process Yourself Against A Local CORS

I am using OPUS to post process static observations.

That is an interesting twist with OPUS PROJECTS that I was not aware of. Thank you.

I would humbly suggest two receivers. The price of OPUS grade static receivers are affordable, especially if you are going to be using them for a lot of jobs. Igage has affordable receivers that I use.

Observing the two points at the same time will allow you to to post process the points, and have a baseline between them. The same data can be submitted to OPUS as a blunder check.

You can use Topcon Tools in Demo mode, or GNSS Solutions to process the baselines and not be out any money for processing software.

OPUS is awesome, but I am old fashioned and like to have a static baseline on larger jobs. I use OPUS as seed coordinates, and as blunder checks. I have attended the OPUS Projects class, gut I believe it would be tough to gain much benefit by only having one receiver.

I hope this helps. Good luck

How many are too many?

I have 13. I process networks.

Get 2 receivers, or do it 2x for more strength.

I'm with Nate on this one. As much as us old timers like GPS, it tends to be over rated IMO.

Plus I question why anybody would ever want to only have one receiver when they don't understand the data they are working with. Not being critical, just a question.

OPUS will give you solutions on each point, but then what? You will find error, or at least a discrepancy. If it's good enough for your project - ok fine. I'd do it.

I had 3 cheapy Ashtech static receivers I did exactly what you are talking about. But they all ran concurrent and I had overlapping data to process vectors on I could verify with my robot. Now I'm into RTK and thinking about going back in time to 6 or 8 cheapy static receivers and stick to the robot I know works. Run OPUS when I need to, but then again I typically create my own NE datum, and use OPUS for the Z.

Get 2 receivers, or do it 2x for more strength.

Maybe you do not understand my question. What makes you think that I do not understand data?

I wrote that I am establishing a basis for the survey. I did not say I was relying solely on the one receiver for the entirety of the survey.

Are you saying that OPUS does not provide accuracy? I collected data on two separate occasions with a resulting 6 millimeter error on my position. I think that will be good enough for future surveyors to locate the project and any monuments that are available.

How do you accommodate enough staff to run 6 or 8 receivers simultaneously?

Finally how much is a "cheapy" receiver?

How many are too many?

I would say that is too many. Do you have staff to operate all the receivers? If not how do you get them to collect data during the same time period?

In the "old days" before CORS we would use two receivers on published positions and two on positions to be established. We needed four operators and synchronized watches to set our start and stop times.

I think a total of four receivers is good enough.

Thank you. The receiver I have is Igage and they are affordable.

I've Regularly Used Up To 10

And could have used more on the bigger networks.

Paul in PA

I've Regularly Used Up To 10

I am impressed. I am not doing very big projects, nor do I create networks. Just the rural boundary for a conservation or historic project to use in making use of the state coordinate system.

Two would be enough for me to establish a base line if I can get the money for a second.

However, I am curious about what type of project would use 10 or more receivers. Would you be to establish a city or town coordinate system?

My latest project is a grant proposal for the renovation of a historic building. It was known as Schoolhouse #1 in our town.

Get 2 receivers, or do it 2x for more strength.

I checked my notes from the OPUS class and found a general rule that horizontal accuracy can be in the 1 centimeter to 2 centimeter range.

I've Regularly Used Up To 10, BY MYSELF!!

> However, I am curious about what type of project would use 10 or more receivers. Would you be to establish a city or town coordinate system?

None. Save for someone attempting to create a primary control network over a state the ends in "Dakota", where few CORS exist. Even then the coordination of 10 crews over such a large area is just asking for trouble, especially with synchronized sessions. You will most likely lose money on such a job. Then once the project is finished, you will be left sitting in the office, laying off your eight extra surveyors, and stewing as your 10 receivers all look you right in the eye and laugh.

P.S.
This does not apply to government agencies who scoff at the fool who only owns 10 receivers.

I've Regularly Used Up To 10, BY MYSELF!!

> Even then the coordination of 10 crews over such a large area is just asking for trouble, especially with synchronized sessions. You will most likely lose money on such a job. Then once the project is finished, you will be left sitting in the office, laying off your eight extra surveyors, and stewing as your 10 receivers all look you right in the eye and laugh.

I've done a number of projects like this with as many as 10 receivers, but more often 8 or 9. It's a carefully-choreographed dance, and it does require lots of planning and coordination with all involved. We always had one guy -- me or a consultant I worked with -- who kept up with the others as they moved through the project, carrying a spare setup in case someone was unable to make it to their assigned station on time or ran into equipment trouble. The troubleshooter also downloaded the receivers at the end of the day in a location convenient to the day's work.

I always made money on those jobs, and they were a lot of fun. We used public agency staff to man -- and sometimes to supply -- the receivers, so no layoffs were required.

Get 2 receivers, or do it 2x for more strength.

> I checked my notes from the OPUS class and found a general rule that horizontal accuracy can be in the 1 centimeter to 2 centimeter range.

No disrespect not my, I use OPUS often and it's a great tool to keep in your tool box. I attended an OPUS Projects seminar last year and that is incredible, but I do not have the equipment to utilize it. They all give that 1-3 cm stated accuracy, but the vertical does get real iffy unless you can live with 7-9 cm.

Just remember that NGS invented all this GPS gizmo stuff and they are the ones "reporting" said accuracy, and are thus checking their own work on which we rely upon. We have the responsibility to our clients to assure that OUR work meets standards, so we check and verify against them. You are the one signing your name on it and then assume all liability totally regardless of what your OPUS printout says.