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OPUS-derived Positions Adjusted in Star*Net  

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Kent McMillan
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I've noticed that an increasing number of folks are using OPUS to get NAD83 coordinates of control points that are then adjusted with either:

- other GPS vectors between the control points,
- conventional survey measurements, or
- both.

For those who use Star*Net-Pro V.6, it is remarkably easy to enter the NAD83 coordinate reported by OPUS, but weighted by their uncertainties, also as reported by OPUS, in the form of the elements of the covariance matrix in the Extended Solution Report that can be requested for an OPUS solution.

This thread from last year describes the process of converting the coordinates reported by OPUS to a form of observation that Star*Net will treat as a GPS vector of nominal length zero (with the same uncertainties reported by OPUS).

[msg=216517]Earlier thread on subject with worked example[/msg]

Among the things that this will allow a fairly rigorous treatment of are repeat OPUS solutions on the same point that deliver somewhat different coordinates, each set with its own uncertainties. Likewise, it's an excellent way to include various OPUS solutions throughout a network without making the false assumption that any of them are exactly correct and error free (which they are not, of course).

I've used this technique for more about nine years or so and have been impressed by how powerful it is to treat the OPUS solutions as coordinates subject to random errors within certain quantifiable ranges, as it does.

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BigE
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 BigE
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Are you submitting OPUS static or RS or a project?
When I did my little program it was all about project results. And someone crashed my program right away giving it a RS solution.

I'm still waiting on field data to verify my programs results.

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Kent McMillan
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> Are you submitting OPUS static or RS or a project?

Both, depending. I don't mind taking five hours of L1/L2 observations and cutting it into five one-hour segments for submission to OPUS-RS and then adjusting the multiple answers for the same point in Star*Net using the covariances returned in the Extended Output for each solution.

Since the OPUS and OPUS-RS processors are fundamentally different, I don't see any particular problem with including an OPUS Static solution from all five hours as was done in the example shown in the thread linked.

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BigE
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 BigE
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> > Are you submitting OPUS static or RS or a project?
>
> Both, depending. I don't mind taking five hours of L1/L2 observations and cutting it into five one-hour segments for submission to OPUS-RS and then adjusting the multiple answers for the same point in Star*Net using the covariances returned in the Extended Output for each solution.
>
> Since the OPUS and OPUS-RS processors are fundamentally different, I don't see any particular problem with including an OPUS Static solution from all five hours as was done in the example shown in the thread linked.

How many CORS things were involved?
But really, do you have my program? Can you try it out please?
It needs the XML data. It should be able to handle the RS or a project solution. My NGS contact seems to be unknowing about this.

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Kent McMillan
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> How many CORS things were involved?
> But really, do you have my program? Can you try it out please?

I'll bite. What does your program do?

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