GPS Static Large Network Planning

How many receivers will you have? Are you conducting the post-processing or is it being sent to OPUS?

Is there a good way to determine this through a spreadsheet or some other tool?

I start by building a CAD drawing of the network layout -- often with a satellite imagery backdrop -- then draw session vectors based on the number of receivers and the number of sessions per day that I intend to observe.?ÿ (Don't forget to allow plenty of travel time between sessions!)?ÿ Each session gets its own CAD layer, with the layer names coded to indicate the session (i.e., the 3rd session of the 4th day of observations gets a layer name of D4S3) and with a different color for each session.?ÿ This allows me to see which receivers stay put and which leapfrog from session to session.

Next I compile a spreadsheet showing which receiver goes to which station for each session.?ÿ This isn't an automated operation, but it's easy enough to do, even with a large project.?ÿ The spreadsheet becomes the observation schedule, which is printed and distributed to the observers along with station maps, descriptions, observation log sheets and contact information.

I've successfully used this approach on projects with as many as 10 receivers and 300 stations.

I will have 8, and yes it will be sent to OPUS

8 receivers for 15 control points plus a benchmark? You are selling your project short with 2 hour observations. In one day you could observe everything for 3 hours plus each. The longer observation time greatly improves your final elevations.

You do not say where you are and that would affect your ability to use OPUS-RS.

Personally I would go for two days, 8 4 hour sessions then move 4 receivers for the afternoon. Next cover yesterday's unoccupied points all day and move other receivers around throughout the day on previously occupied points. Your GPS post processing software can handle it all. With a 5 mile project area I would not hesitate to add as many L1 only receivers as I could find.

When you plan your occupations cover every other planned point first, then you are only moving receivers a short distance.?ÿI have found that working alone I could get as much done with 4 receivers as with 5, occupations with 5 got longer as I could only move units so fast. Two men could do this project, 3 cover more contingency and any more are only dependent on receivers that cannot be left alone.

Paul in PA

If you are planning on using standard OPUS or OPUS-RS for that matter then why bother planning at all.?ÿ All you are going to have is 24 to 30 discrete observations.?ÿ You will get the same if not better results with multiple 10 minute RTK observations.?ÿ For more improvements set the base on multiple points.

...trying to find a way to efficiently plan out the right amount of occupation's for about 12 to 15 control points over a 5 mile span...

Here is how I'd do that.

First, I'd set major control points every mile or so along the route. But not within the right of way. Somewhere nearby in a very clear area off the route, outside of the proposed construction zone. These are your RTK Base stations. Set them in parks, schoolyards, open fields that won't be plowed, etc.?ÿ Just make sure that they have very clear sky, are secure, and won't be disturbed for the duration of the project (including the construction phase). Monument them well. Run static vectors or multiple 3-5 minute RTK vectors between them.

Collect 2-4 hrs for OPUS at each of these major control/RTK base stations. This can be done while running the next step....?ÿ?ÿ

Then establish your control along the route of survey for use by total station. I'd be establishing them every 700-800 feet and?ÿintervisible. This would give me about 35 control points, not 15. (If you stick with 15 then your spacing will be more like 1800 ft, and you will be taking topo shots 1000'+. If that works for you, go for it.?ÿ Doesn't change the basic principle.) Tie each of these points from the nearest 2 of your 5 RTK base stations, each tie consisting of a 90-180 second occupation, followed by rotating the rod 180?ø and repeating the occupation.?ÿ

Simultaneously adjust the lot in the LS package of your choice.?ÿ Do not "fix" the OPUS positions in your adjustment. Allow them a small standard error. StarNet, for example, allows you to use the OPUS Extended Report, which includes error estimates.?ÿ

Note that the length of time to occupy with RTK is a subject with lots of opinions but no clear answers.?ÿ My advice is to watch the coordinate quality numbers more than the occupation time.?ÿ Collect for what ever time it takes to get the good quality numbers. Bad locations don't get better by occupying longer.?ÿ?ÿ

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If this campaign is not going to be processed as a network, I agree with John Putnam, in that the only real planning involved are observation times to comply with the flavor of OPUS to be used and making sure each station is observed at least twice. For a true network using the NGS-58 & 59 guidelines, what Jim Frame proposed is an excellent solution. I can attest to Jim's experience with planning, and successfully executing, large network campaigns using 10 receivers.

Just running OPUS on many points is not a control network. Let's not even discuss that.?ÿ?ÿ

JIM this strategy was very helpful. And plotting it in CAD really helped me see the overall picture of how it was to come together. I'm in the spreadsheet step now, to ensure every point has the desired redundancy.?ÿ

Sean